CON T E 11" T S

INTRODUCTION

EVOLVING I}~ROVED VARIETIES

SOIL AND CROP 111ANAGEMENT

CONTROLLING PESTS AT FARNERS I LEVEL

ON-FARM AND ADAPTIVE TRIALS

_ - - - - - - - - - - - -- 1

- - - - - - - - - - - - - - 7 - - - - - - ~ - - - - - - 13

- - - - - - - - - - - - - 23 INTERNATIONAL AND NATIOnAL CO-OPERATION - - ... - - - - - - - - - 31

TRAINING - - - - - - - - - - - - 33 PUBLICATIONS

PERSONNEL

NOTE:

- - - - - - - - - - - - 34 - - - - - - - - - - - - 36

This report in its present form has not been officially approved by

the West Africa Rice Development Association, Monrovia, Liberia.

INTRODUCTION

An estimated 200,000 he. of tidal and associated swamps are cultivated

in' The Gambia, Guinea, Guinea-Bissau, Nigeria, Senegal and Sierra Leone.

These swamps are relatively more fertile than other rice environments and

farmers' average yield is 2.0 tons/ha.

Over 100,000 farm families in the region are dependent on rioe cultivation

in the mangrove swamps f~r their livelihoM. They are confronted with several

environmental and stl.cio-economic constraints.

Research at the WARDA Rokupr Station is undertak()n to devel~p improved

technologies for higher and sustainable producti~n for the resource - po~

~· swamp riee farmers in West Africa. With a multi-disciplillar7 team

approach, we accomplish this objective in collaboration with the national

agenoies and organisations responsible for research, training andtechnol~gy

transfer in the various member cormtries.

In northwest Sierra Leone, along the Great Scaroies and southern

Sierra Leone along the Bumpeh river about 53% of the farmers in the short

season areas are now growing ROX 5, WAR 1 and Rohyb 6. This means an increase

of up to 1.5 tons/ha of their production. The use of improved varieties and

the single axle traotor/power tiller as recommended by us formed the basis f~

the proposal for donor \EEC) sponsored Northwestern Integrated Agricultural

Development Projeot (NWIADP) at Xambia, Sierra Leone. In The Gambia and

Guinea-Bissau farmers grow ROX 5 to the extent of about 20 and 60 peroent,

respectively, along side their traditional varieties. Additionally, four

other varieties also introduoed by WARDA are being multiplied for distribution

in Guinea-Bissau.

Our achievementBover the years have been aooomplished against a

background of limited laboratory facilities and infrastructure, logistio

problems, erra&1b water and electrioity supply, and poor oammunioati~ links

with Rokupr, ~ur operating base (no telephone/cable/telex/radio).

Looking ahead, emphasis will be placed on responding to the changing

needs and strengths of national programs. We will continue to find solutions

to the environmental land biologioal stresses to rioe in the mangrove swamps

in closer partnerShip with National Agrioultural Researoh Systems (HARS) to

enable low income farmers of this rice environment to have a higher and

tmStainable produotiono

EVOLVING IMPROVED YARIETUS

The varietal improvement program focused on the identification from

existing varieties, and breeding of new higher yielding varieties with improved

tolerance to the major environmental and biological stresses suoh as salinity,

iron toxic! ty, acidity and orab damage.

Germplasm Introduction

Since 1977, approximately 6,000 varieties have been introduced and screened

for their adaptation to the. mangrove swamp environment. Selected intr<~uotions

with high-yielding ability, fertilizer responsiveness, toleranoe to s~il

stresses, resistanoe to major inseot pests and diseases, and suitable plant

stature have been identified and are being exploited in the breeding program.

Materials introduoed and soreened in observational trials in 19S7 were

nbtained through. IRTP and oomprised of 680 lines from 1986 IRRSWON, ITPRON,

IRSATON and Aoid lowland soreening set.

IRRSWON: The trial was established on a site subjeoted to shallOW tidal

flooding (.)a 20em) for three or four days at each period of high tide, As in

previous years many of the entries in the nursery proved of interest and 38

were seleoted for further testing. Most of the seleotions were intermediate

statured, short duration lines suitable for mangrove swamp areas of

Guinea-Bissau and southern Senegal.

ITPRON: The test lines were planted on a site subjected to deep tidal tlood1n«

( ,. 700m) • Thirty-five lines performed exceptionally well with higher grain

yield and better phenotypio aoceptability scores than the oheck varieties.

These were selected for further yield testing. Sixteen of these selections

were tall statured, long duration varieties (180-200 days) considered

appropriate for the deep flooded long season areas.

IRSATON: The salinity screening set was transplanted at Balanoera, a salt

affeoted site in northwest Sierra Leone. The seedlings were transplanted

early in July to expose them to severe stress at the seedling stage. However,

severe crab damage was encountered due to severe infestation by crabs at the

trial site, and most test lines were wiped out. The Surviving lines showed

poor adaptation and only small amounts of seeds were harvested from BR9-17-4-2,

CISADANE, IR26916-13~1-1, IR48, IR32307-107-3-2-2, IR9808-9-2, Pokkali and PR106.

Acid Lowland Screening Set: The entries were planted on a tidal site with

initial PH of 4.2. The soil pH increased during the course of the trial. Twelve best entries rated on their reaction to soil problems and ability to

withstand tidal flooding were selected, and will be further tested next season.

2.

Germplasm Cellection and Characterization

Collection and evaluation of traditional mangrove swamp rice varieties

from the region were initiated in 1977 to establish the varietal types favoured

by farmers and to provide a source of well-adapted germplasm for our breeding

pregram. At the end of 1987, the collection had 768 accessions from

Sierra Leone, The Gambia, Guinea, Guinea-Bissau, Nigeria and Senegal.

Breeding Pregram

The chances of identifying varieties that are better than the traditional

varieties from existing improved ones are low. A breeding program was therefore

initiated in 1978 to develop higher and stable yielding varieties for the

different mangrove swamp conditions encountered in the region.

During 1987, 34 new crosses were made to' incorporate desirable

characterist·· 0 such as tolerance to' salinity, iron toxicity and ree.ietane& t~

major insect pests and diseases into improved varieties.

This season, the breeding nurseries contained over 3,500 segregating lines on station and ~ver 200F

4 and FS populations at off-statiO'n problem sites.

A bulk selection method was used to improve on the selection in deep flooded

and adverse tidal swamps. A rapid generation advance teohnique was used to

speed up the generation turn~ver rate of long duration photeperiod sensitive

lines. Over 2,000 plant selections were made and advanced to the next

generation.

Adverse Soil T~lerance: Tidal and associated rice fields cover a wide spectrum

of Boils. The development of genetic materials that are adaptable to these

conditions will allow for expansion ef land under rice and provide a means of

increasing annual production of mangrove swamp farmers. In 1987, a total of

260 varieties were screened for salinity (180), iron toxicity (40) and acidity

(40) by growing the entries in specific problem soils contained in concrete

troughs. A total of 4,880 traditional and improved varieties/advanced lines

have so far been screened for this purpose.

Several promising advanced lines including WAR81-2-1-2, ' WAR77-3-2-2,

WAR81-2-1-3-2, WAR98-6-1-9-1 ,WAR5O-~ jWAR74-23-2-2-B-2, WAR79-4-Rl-2-1 and

WAR91-2-4-1 have shown multiple tolerance to soil stresses. Under field

testing in moderate salinity (6-8 mmhos/cm) at an iron toxic site at Balancera,

northwest Sierra Leone, some of these advanced lines gave yields over 2.0 .t.

tons/ha (Table 1).

Further, 30 WARDA - Rokupr F 4 lines and 11 cuI ti vars were screened in the

laboratory and field, respectively for tolerance to iron toxicity at the WARDA

Nursery farm at Suakoko, Liberia.

3.

Some of the tolerant F<_ lines identified were WAF\.9a-2-6-1, WAR100-3-2-1,

WAR100-3-4-1, WAR98-6-.~··1 and WAR100-4-7-1. Two of the cultivare that were

rated as tolerant to iron toxicity were WAR81-2-3-1 and Fant 213. These would

serve as donors for iron toxicity tolerance in future breeding programs.

Table 1. Grain yield and tolerance ~cores of some promising lines

in saline and mild iron toxic field - Balancera,

Sierra Leone, 1987.

Line

WAR77-3-2-2

WAR 1 (Rohyb 15)

WAR50-3O-1-3-1

WAR81-2-1-2

Rohyb6-WAR-6-2-B-2

WAR29-3-3-1

WAR72-2-1-2

WAR52-284-3-2-1

ROK 5 (check)

Cross

IR4595-4-1-15/Merr 10SA

Wellington/SR 26//CCA

B5141B-Kn-1-1/Konday 225

Miniku 32A/I. Mahsuri

CCA/RH 2

Mahsuri/Pama Bangura/ / Ginsa Killing

Merr 108A/BG90-2

Faro 15/Tail Kokoyo

Wellington/SR 26

Grain Yield

(tons/hal

3.2

3.1

3.0

3.0

2.6

2.4

2.2

2.2

1.8

MT = Moderately tolerant; f.m = Moderately Susceptible.

Reaction to Salt Iron

MT

MT

MT

MT

MT

MT

MT

MT

MT

toxicity

MS

MT

MS

MT

MS

MT

MT

MS

MT

Disease. Insect and Crab Damage Resistance: Mangrove swamp rice is attacked by

diseases, insects and crabs. Of these, blast, brown spot, leaf scald, stem

b~rers and tidal swamp crabs are most important. Breeding for resistance for ~

these pests is therefore essential for sustainahle rice yields.

Over 200 ric~;varieties/lines have been evaluated by 1987 to identify

sources of resistance to crab attack. Cultivars that have shown some amount of

resistance to crabs such as Boyah 246, Damalai 247A, D~lai 2478, and Rolontho

265A were used this season as donors in the breeding program for crabs. Also in

1987, 40 promising rice varieties/advanced lines were screened and their mean

percent crab damage ratings were tested for correlation with some morphological

characteristics of the rice plant. The correlation between percent crab damage

and leaf length was highly significant (r = -O.tJ-.iP**.). Eight varieties including

five Rokupr bred advanced lines were outstanding with crab damage ratings of less

than five percent (Table 2),

4.

Table 2, Screening for resistance to crab damage among promising

rice selections - Rokupr, 1987.

Variety Source/Cross

IR 25429-R-WAR-1 IRRI/WARDA /- RGA

Raden Mas Asia

WAR 72-2-1-1 Merr 1081l/BG90-2

WAR 77-3-2-2 IR 4595-4-1-15/Merr 10BA

WAR 44-5-5-2 Raja Sal/BL 4E

WAR 44-21-3-2 Raja Sal/BL 4E

WAR 49-5-1-3-1 B 541BKN-47-1-1/Yenken Yonkah

SL 22617 RRS - Rokupr

ROK 5 (Susceptible Check) Wellington/SR 26

WAR = Rokupr bred advanced lines.

Yield Trials of Promising Varieties/Advanced Lines,

Crab damage level ~~)

4.3

3.3 1.0

3.0

4.3

4.7

4.7

4.3

13.7

In continuation with the testing of varieties/advanced lines selected in

previous seasons, a number of observational yield trials (OYTs), replicated

yield trials (RYTa), farmers' field trials (FFTs) and advanced variety trials

(A VTs) were conducted during 1 987.

~: Three OYTs were conducted during the season. One trial sited in the

associated swamp tested short duration varieties (120-135 days) for types suited

to bunded swamps in the north of the region. The second and third trials were

sited in the tidal mangrove swamp and tested medium duration varieties (135-155

days) and long duration ones (155-200 days) for suitability for use in Sierra

Leone, Guinea and Nigeria.

In the short duration associated swamp trial, 38 varieties we~e tested

against IR 1073-143-2-3 as check. The trial was located at the edge of a swamp,

with low natural fertility and mild iron toxicity problems. A basal application

of 60 kg N/ha and 20 kg P205/ha were given. Eleven varieties outyielded the

best check plot and were selected on this basis (Table 3). A further 10

varieties were selected on the baSis of their, performance in the field, and were

shorter in duration than the check variety. Their earliness coupled with their

short stature indicated that these materials would be suitable for use in

non-tidal swamps in the short rainy season areas of northern Guinea-Bissau and

southern Senegal.

5.

Table 3. Performance of new selections from" .bservational yield

trials of short duration varieties under associated swamp

oonditions - Rokupr, 1987.

Variety Yield

( tons/ha) % Yield Plant Growth

increase height! Duration ~

over adja- (cm) (Days) cent check variety

WAR 115-1-2-10-5 5.6 68 95 132

WAR 115-2-2-1-1 5.5 36 87 128

BR 50-120-2 5.0 57 81 132

IR 29912-63-2-2 4.7 49 92 128

WAR 115-1-2-11-2 4.6 45 93 135

WAR 100-2-15-1 4.3 100 90 133

WAR 100-2-1 2-1 4.3 44 92 135

IR 1073-143-2-3* (Mean of 20 plots) 3.1 98 135

* Check variety; WAR = Rokupr bred advanced lines.

In the medium duration tidal mangrove swamp OYT, 47 lines were tested

against ROK 5. A basal dressing of 60 kg N/ha was given. Two entries,

BW 295-5 and BW 295-4, out yielded their adjacent ROK 5 plots and were selected

along with eight more varieties which showed good performance in the field.

The selections were comparable to ROK 5 but up to two weeks longer in duration

and were virtually all intermediate statured. These would seem suitable for

flooded swamps in the long rainy season zones.

Sixty-eight long duration entries were tested on a site g ~jected to deep

tidal flooding. Fertilizer application was the same as for the tidal mangrove

swamp OYT. Yields recorded for the trial were low, with the check variety,

Kuatik Kundur averaging 1 .9 tons/ha. Twenty-eight test varieties including 13

advanced lines, out yielded the best check plot were selected and for the shallow

flooding tidal swamps.

RYTs: Five RYTs, associated (2) and tidal mangrove swamp (3), were oonducted

during the season. The varieties tested were selected introductions from 1986

OYTs but included a small number of advanced lines from the breeding program

and the best varieties from last years' trials. A basal dressing of 60 kg N/ha

was given to all trials while 60 kg P205/ha was also basally applied in the

associated swamp trials.

RYT (Short Duratio~: Fifteen varieties were tested against IR 10781-143-2-3

as check in the assocated swamp, BG 380, BR400-1 and IR 21855-53-2-1-2

Significantly outyielded the check variety with average yields of 4.2, 3.8 and

3.7 tons/ha, respectively.

RYT (Medium Duration): Two RYTs, one each in the tidal and associated

mangrove swamps were conducted during 1987.

In the associated swamp, 15 varieties were compared against ROK 5 as check.

The trial was conducted in a fertile swamp in the seepage zone. Five varieties,

WAR72-2-1-1, WAR77-3-2-2, WAR81-2-1-3-2, RTN16-1-1-1 and WAR 1, outyielded ROK 5

although not Significantly. However, WAR72-2-1-1 and WAR77-3-2-2 showed multiple

tolerance to salinity, iron toxicity and acidity.

In the tidal mangrove swamp, 14 varieties were compared with ROK 5 as

check. The best four varieties, W!~ 1, Rohyb4-WAR-1-3-B-2, B981d-51-35-1,

Rohyb4-WAR-1-1-B-1 were not significantly different from ROK 5. WARS7-10-2-3-2,

WAR73-1-M4-5-1-1-2, and Haji Haroun yielded significantly the same, but lower

than ROK 5.

RYT (Long Duration): Two RYTs to test pro~s~ng long duration varieties were

conducted in tidal mangrove swamp during 1987. Attempt was made to stratify

varieties into two categories according to duration (155-180 days and 180-200

days).

In the longer duration category (180-200 d~s), 12 entries were compared

with ROK 10 and CP 4. The first 11 varieties were not significantly different

from CP 4 and ROK 10. The top three varieties, WAR73-1-M2-1, WAR73-1-M1-4 and

WAR44-64-2-1 gave yields of 3.8, },7 and 3.5 tons/ha, respectively and

significantly outyielded MatCan~, an iron toxicity tolerant variety selected

from 1986 IRSATON with grain yield of 2.5 tons/ha.

In the second trial (155-180 days) only two varieties WAR42-82-2-3-1 and

WAR 1 02-1-3-1 significantly out yielded the check variety, Kuatik Kundur.

WAR42-82-2-3-1 and WAR 1 02-1-3-1 showed very good seedling blast tolerance

while Kuatik Kundur showed moderate tolerance.

7.

SOIL AND CROP MANAGEMENT

In 1987 emphasis was placed on improvement of soil fertility in acid

sulphate soil conditions. Research to identify nitrogen responsive rice

varieties among newly bred lines and to develop easily adaptable techniques

for improving nitrogen use efficiency in mangrove swamps continued. Studies

on utilization of Azolla in swamp rice production also continued.

Improvement of Soil Fertility

Efficacy of Phosphate Fertilizers: Phosphorus is a major limiting nutrient

for rice crop under acid soil conditions. In the past, moderate application

of Superphosphate (40 kg P205/ha) to rice on these seils improved growth and

brought about significant responses to applied nitrogen but higher levels of

phosphorus have not had significant effects in increasing rice yields. Past

research at Rokupr showed that phosphorus applied to mangrove soils became

rapidly bound to iron and aluminium. Much of the response obtained with the

application of phosphorus on these soils has been attributed to immobilization

of iron and aluminium in the soil, especially at the early stages ~f rice

growth. Increasing the availability of phosphorus is therefore essential for

increasing the productivity of rice in these soil conditions.

A trial was initiated in 1986 to determine the efficiency of superphosphate

and phosphate rock materials, such as Taiba rock phosphate and Matam rock

phosphate from Senegal, for rice production in acid soil conditions and to

evaluate intensive use of phosphorus availability.

In two consecutive seasons of the trial, application of single superphosphate

has been more effective than the rock phosphate materials in improving rice

yields, but phosphorus levels above 40 kg P205/ha have not been effective in

increaSing rice yields irrespective of the form of phosphorus applied (Table 4).

The apparent lack ~f response to application of the rock phosphate materials

presumably resulted from their low P dissolution rates and rapid immobilisation

of phosph~rus by iron and aluminium under acid sulphate conditions. The 1987

season results indicated no residual effects to the application of phosphorus

in previous seasons even at the high levels of application.

Amelioration of Acid Soil Conditions: Soil groups in mangrove swamps range

between constantly flooded pyrite saturated subgroups and seasonally aerated,

leached aluminium saturated clays with reserves of pyrite below 60cm in the

subsoil. Rice grown on the latter are subjected to toxic levels of iron and

aluminium and a deficiency of phosphorus. Multiple nutritional disorders and

severe infestation of brown spot disease are usually manifested by the crop.

8.

Table 4. Rice response to levels of phosphatic fertilizers in acid

soil conditions on the Swamp Catena at Rokupr, 1987

(Var. ROK 5).

Phosphatic Fertilizers

CAntrol - without Phosphorus

Taiba Phosphorus Rock

Ma.tam ,, - " Single Superphosphate

Taiba Phosphate Rock

Matam " "

Single Superphosphate

Taiba Phnsphate Rnck

Matam " " Single Superphosphate

~

Level of applied P20

S kg/ba*

40

40

40

80

80

80

120

120

120

Mean Grain Yield

( tons/ha)

3.1 c

3.8 abc

3.8 abc

4.1 ab

4.0 abc

3.3 abc

4.2 abc

3.7 abc

3.9 abc

3.8 a.bc

Means followed by the same letter in the column are not significantly

different at 5% DMRT.

* Nitrogen at 80 kg/ha was uniform.

Lime requirements based on s~il test for acid sulphate soil conditions

are very high (16 tons/ha). In the past, regular application of 40 kg P20S/ha

superph~sphate has been necessary for improving soil fertility conditions and

rice yield under these s~il conditions at Rokupr. Liming at low levels

(3 tons/ha) plus moderate application ~f phosphorus have also been found

effective for improving rice yields in acid sulphate soils. Research at WARDA

Rokupr in 1985 and 1986 showed that incorporation of decomposed rice husk

(plus bran) as soil amendment at 10 tons/ha was effective in improving nutrient

availability and rice yield under acid soil conditions. With the incorporation

of rice husk, conSistently higher grain yield responses were obtained to

applications of 80 kg and 120 kg N/ha. The organic amendment sustained higher

levels of productivity, yielding 0.6 tons/ha more paddy on average than

treatments without husk in the second season after application.

9.

In 1987, the interaction of graded levels of 0, 2.5, 5 and 10 tons/ha of

decomposed rice husk (plus bran) as soil amendment with 80 kg N/ha and

40 kg P205/ha on yield of rice in acid soil conditions were examined at Rokupr.

Significant improvements in rice yields were obtained with the soil

amendments even at the lowest level of husk application. Nitrogen and

phosphorus were also effective in improving rice yields. Addition ef

40 kg P20,/ha increased grain yield responses to the levels of rice husk applied,

except at 10 tons/ha (Figure 1).

The indications were that incorporation of decomposed rice husk (plus bran)

reduced the toxic effects of aluminium and enhanced nutrient availability to

rjQe. Lew response to applied phosphorus at 10 tons/ha of the decomposed rice . C •

husk suggested that the nutrient may not be limiting for rice growth under high

levels of soil amendment. Presumably the contents of phosphorus and Silicon in

rice husk, as well as the ability to complex with oxides and hydroxides .f iron

and aluminium may be important attributes of the soil amendment in the

amelioration of the nutritional di&orders encountered on these soils. Future

trials should examine the effect of other organic materials such as rice straw

on nutrient availability and their effect in sustaining rice yields under acid

sulphate soil conditions.

Improvement of Rice Yields with Azolla

Complementary use of Azolla and Chemical Nitrogen: Earlier trials conducted at

ROkupr demonstrat$d the potential of Azolla as a source of nitrogen for rice

production in the associated mangrove swamp. Incorporation of one crop of

Azolla (17-20 tons fresh weight-FW/ha) before transplanting rice increased rice

grain yield significantly above the control. A second incorporation .f Azolla

two weeks after transplanting guaranteed similar yields of rice as 40 kg N/ha,

the recommended dose of nitrogen if applied by injection technique·. Different

methods of Azolla cultivation with rice were evaluated. Cultivation.f Azolla

(ADUL 54 pp) as a mono crop was rapid, yielding a biomass of 2.32 kg-FW/m2 on

average within 15 days of innoculation. As an intercrop with rice, Azolla

biomass production averaged 1.74 kg FW/m2 in 28 days. Availability of

phosphorus and sunlight intensity were impotant factors a£fecting Azolla growth,

Despite a slower growth rate of Azolla, intercropning it with rice was

advantageous in reducing the weed infestation of rice considerably. As much as

50% reduction in weed infestation has been achieved with Azolla rice intercrop.

The effect of Azolla in sustaining rice yields were determined in subsequent

trials.

GrSl.i il Yi,.ald tOilS/ ha • .

4 . 0 r; .'l ,. .. ;;: u .. 8%

3 .0

2.0 o Without Pho=p~~ ru~ .

1.0

o ~r---------~-------·-·~·'~--------~------~ o ~ • .5

Fig ')! I n teraction of I'ice 1 .. 1··· · . ':' ) '>-4_, . ..

s oi l conditions - Eot.: t.~ l1l' l~l:Y ).

1Q .. ()

in <:i.c i d

10.

One s8il incorporation of A~oll~ is generally feasible under humid tropical

rain-fed conditions. This facilitates an early build up of soil N which

declines as the crop matures necessitating supplementary nitrogen for maximizing

rice yield. A trial was conducted in the last three seasons to determine the

trend in soil fertility and sustainance of rice yields with different methods ~f

Azolla cropping and supplementary levels of applied nitrogen in the associated

swamp at Rokupr • .

Incorp~ration ef Azolla before transplanting rice gave consistently higher

yields of rice than Azolla/rice intercrop (Table 5). Over the three seasons of

the trial, the relative affects of Azolla cr"'pping on ric.e yield were stahle.

Residual effects from Azolla cropping were not ~bserved and nitrogen x Azolla

interactions were also absent presumably because of the level of AzelIa biomass

used.. Incorp"'ration of higher Azolla biomass (2-3 crops of Azolla) would

contribute a greater amount of nitrogen to the rice crop and influence response

to the levels of chemical nitrogen applied.

Jable 5. Rice grain yield under long term Azolla cropping in the

associated mangrove swamp at Rokupr, 1985-1987 (Variety ROK 11).

Azolla

Creppini'

Without

Monecrop

Intercrep

Mean 1985 3.6

4.7 a

4.0 'b

Yield of Grain 1986

c 3.9 b

4.7 a

3.9 b

(tonsLha2 1987 Ayera~

4.1 b 3.9 b

4.8 a 4.7 a

4.1 b 4.0 b

Means fellewed by the same letter in the column are not significantly

different at 5% DMRT.

c. V. C%) 9.5 8.2 9.6 9.1

Response to nitrogen in the range .. f 0-60 kgjha was linear under all

methnds of Az,.,lla cropping (r = 0.99*** without Az~lla; r = 0.97* Azolla monocrop;

r = 0.96* Azel;ta intercrop). The effect .. f Aznlla incorporation plus 60 kg Nlha

on rice yield was additive, and increased grain yield of rice over the

untreated contrel by 82% as compared with an iricrease of 5~ in the absence of

Azolla. Application of 60 kg Nlha under intercrepped Azolla increased rice

yield by 55%.

11.

Fertilizer Application and Respon~

Varietal Response to Nitrogen: Cellaborative studies with the breeding

section have identified HOK 5, ROK 10, 1:TAR 1, and i'lAR44-50-4-1 as nitrogen

responsive varieties. ROK 5 was found to be better adapted to the

associated swamp environment and efficiently utilized soil lJ for grain

production in earlier trials.

In 1987, trials to identify rices with efficient utilization and high

grain responses to nitrogen among the newly developed varieties for mangrove

swamp environments were conducted on the tidal mangrove and associated swamr s

at Rokupr. Four varieties were evaluated in each sub-ecology over a nitrogen

range of 0-150 kg N/ ha.

On the tidal mangrove swamp, application of 60 kg N/ha was optimum for

increasinff grain yield of rice irrespective of the variety tested. The yield

perforJMD.ces of ~JAR44-50-4-1 and ROK 10 (check) were s ;. milar, out yielding

lNAR39-17-2-2 and WAR44-5-5-2 (Table 6).

Table 6. ~lean grain yield ef rice showing response of some newly

developed varieties to nitrogen in a tidal mangrove swamp

at Rokupr - 1987 season.

Varieties Ni troge~'-apPlf;d'-=r~lh8I'-----"---'---

o 30 60 90 1 20 150 Mean

Tv'lAR30-17-2-2 1.7 1 .9 2.7 2.6 2.7 3.0 2.4

\vAR44-5-5-2 1.4 1.9 2.6 2.5 2.8 2.6 2.3

'itT AR44-50-4-1 1.6 2.0 3.2 3.3 3.4 3.2 2.8

ROK 10 (check) 1.8 2.1 2.;1 :2.:2 :2.0 .2,..4 2.8

Means 1.6 2.0 2.9 2.9 3.0 3.1 ----

C.V. (%) Nitrogen = 18.5

C.v. (~; ) Varieties = 13.2

L.S.D. 0.05 for differences between nitrogen 0.43 means = L.S.D. 0.05 for differences between variety means 0.23 =

In contra~t, grain yield response to rice varieties grown on the associated

swamp ecolegy was markedly influenced by the levels of nitrogen applied

(Table 7).

level!1l

12.

Table 7, Mean grain yield of rice showing response 'f some newly

devel,ped varieties to nitrogen in an ass~ciated mangrove

swamp at Rekupr - 1987 seasen.

WI

~tonsLha~ Varieties Nitro~n aEElied 0 30 60 90 120 150 Mean

ROK 5 (check) 1 .6 c 2.0 'bc 2,5 bc 2.7ab 2.8a 2.6ab 2,4

Rohyb6-WAR-6-2-B-2 2.0a 2.6a 2 ... 4a 2.0a 2.3a 2.2a 2.3

WAR81-2-1-2 1.1 b 1,7b 1.5 b 2.5 b 2.5a 2.8a 2.0

WAR81-2-1-3-2 1,7b 2.5a 2.7a 2.9a 3.2a 3.0a 2.7

Means 1.6 2.2 2.3 2.5 2.7 2.7

Means follewed by the same letter in the row are not significantly

different at 5% DMRT.

C.V. (%) Nitr~gen = 22.3

C.V. (%) Variety = 16.2

1YAR81-2-1-3-2 was higher yielding and produced significantly higher grain

yield responses to nitrogen in comparison to the ether varieties.

R.hyb6-WAR-6-2-B-2 was not responsive to the levels ~f nitrogen applied and

WAR81-2-1-2 required relatively high levels ef nItrogen to increase grain

producti,n.

In general the yieldLwere lew and may be indicative ef the lew fertility

,f the seils in the associated mangr~ve swamps. The resuits indicated that

WAR81-2-1-3-2 was adaptable t, the asseciated mangrove swamp environment with

a p~tential for increasing p~oductivity ~~ rice under prevailing conditions.

CONTROLLING PESTS AT FARMERS' LEVEL

The programts thrust was geared toward the development and testing of

effective, low cost and easy to adopt pest control strategies for the small

farmer. Cultural practices that minimize pest infestation were formulated int.

integrated pest management packages and tested for the c~ntrol of the major

pests.

WEEDS

The weed control pngram in 1987 continued work on the development e6 .,

cultural practices for effective weed control. Research to identify suitable

herbicides for weed control especially in the associated mangrove swamps was

alsecfJJ,tinued at Rokupr. :t ~

Cultural Weed C,ijirol

Seedling Establishment Methods: ~his trial was initiated in 1985 to determine

the effect of method of seeding and one handweeding, on stand establishment,

weed gr~wth and grain yield of rice in the associated swamps. The treatments ,

included broadcast ungerminated seeds, broadcast pre-germinated seeds, direct

seed drilling, and 4, 6 and 8 week-old seedf ing transplants.

The 1987 results confirmed the findings .f previous seasons. Rice stand

establishment was lowest with direct seed ~rill and had whe highest weed

infestation compared te the ~ther treatments.

The grain yields, .f transplanted rice were higher than those obtained with

direct seeding. Six week~~ld seedlings (2.4 tons/ha) and 8 week-old seedlings

(2.5 tons/ha) preduced significantly higher yields than the other treatments.

Direct seed broadcast (germinated"' er ungerminated) precludes nursery

preparation and transplanting with a potential for reducing the cost of

production. But, to obtain high yields an effective weed control practict:; ;",

becomes imperative. In this regard, a minimal use of herbicide may be

desirable.

Competi ti ve Ability of D~fferent Rice Varieties with Weeds: This .,trial was

initiated this season to evaluate the competitive ability of 30 ri.e varieties

(Oryzae sativa L.) of various plant stature und~r two weed management levels

(no weeding, and '~ne handweeding at 30 days after transplanting - DT).

Results obtained indicated that the varieties differed greatly in their

ability to supprel!ls weeds. Weed ':- dry weight at 50DT varied from 1.4 €!1m2 for

WAR50-49-1-2-1 (141 .Scm tall) to 9.1 g/m2 for WAR49-S-1-3-1 (126am tall) with

fi!ne bandweeding.

14.

For the non-weeded control weed dry weight ranged from 91.3 g/m2 for

WAR81-2-1-3-2 (96.4cm tall) to 12.6 g/m2 for WAR49-5-1-3-1 (126cm tall).

However, there was no correlation between plant height of the varieties tested

and their abili;ty to suppress weeds. Possibly, the architecture .f the variety

coupled with faster canopy development may suppress weeds more effectively,

owing to shading effects.

Influence of Crop Density on the Competitive Ability of Weed: Rice variety ROK 5

was tested at four densities and two weeding regimes (no weeding, and 'one

handweeding at 30 days after transplanting) to determine their effect on weeds

and rice yields.

The plant spacing of 20 x 15cm (33 hills/m2) provided good control of

weeds than plant spacing er 20 x 20cm (25 hills/m2), 25 x 25cm (16 hills/m2) or

30 x 30cm (9 hills/m2). The unweeded plet of the 20 x 15cm plant spacing

exhibited enl,.. 7.6% reductien in yield as compared to 20.CJfo, 25.3% and 24.4%

in the 20 x 20cm, 25 x 25cm and 30 x 30cm plant spacings, respectively (Table 8).

The results sh~wed that the wider the plant spacing, the higher tbe degree of

weed infestation, with resultant decrease in grRin yield. The closer plant

spacing ~f 20 x 15cm possibly created a less favourable environment for weed

proliferation.

The results indioated that in associated swamps with severe weed problems

the plant density of 33 hills/m2 was ideal for ' minimizing weed competition with

the rice crop.

Table 8. . Effect of four plant spacing on weed growth and grain yield ef

ROK 5 in an associated mangrove swamp at Rokupr, 1987 season.

Plant spacing (cm)

20 x 15 Weeded

20 x 15 Unweeded

20 x 20 Weeded

20 x 20 Unweeded

25 x 25 Weeded

25 x 25 Unweeded

30 x 30 Weeded

30 x 30 Unweeded

L.S.D. 0.05

C.V. (%)

Grain yield

(tons/ha)

2.2

2.1.

2.1

1.7

2.1

1 .6

2.t

1 .6

0.49

17.3

% Reduction in yieldc

7.6

20.0

25.3

24.4

Dry weed weight

(g/m2)

2.5

16.4

2.0

24.6

3.2

23.9

7.8

30.8

11.8

57.9

15.

Nitrogen Application and Weed Control Methods: A field trial in an associated

mangrove swamp at Rokupr evaluated the effect of nitrogen application method

(broadcast at 14 DT, and deep placement hy injection method at 14 DT) and weed

control methods (one handweeding at 30 DT, two handweedings at 21 and 35 DT,

propanil at 91/ha plus bentazon at 41/ha at 21 DT, and an untreated cheo~) on

the growth of ROK 5 and weeds.

Method of N application did not significantly affect the degree of weed

infestation. Nitrogen applied by injection method had the lowest weed dry matter

production while plots without N produced the highest weed dry matter. This is

possibly due to better N-efficiency use by the crop in the N-injected plots which

resulted in vigorous crop growth and faster canopy development, thereby

providing better competition with weeds. Weed control methods affected weed

growth significantly. All weed control methods gave lower weed weights than the

untreated check. Two handweedings had the lowest weed weight, followed by

propanil (91/ha) plus bentazon (41/ha), which provided effective grass and sedge

control.

Nitrogen application and weed control methods affected grain J'ield

Significantly. The N-treated plots gave higher yields than when N was not

applied. Nitrogen applied by injection gave the highest yield but was not

significantly higher than N applied by broadcast. Grain yields of all weed

control treatments were higher than the untreated check. The mixture of

propanil plus bentazon gave the highest yield which was similar to that of two

handweedings (Table 9).

The results indicated that the efficiency of N application can be fully

realized with effective weed control, particularly with N-responsive rice

varieties such as ROK 5.

Chemical Weed Control

Promising Herbicides: Research to identify promising herbicides for weed control

in associated mangrove swamp rice continued during the 1987 season, in order to

identify suitable herbicides for this ecology. All the herbicides tested

provided significantly good weed control than the untreated check (Table 10).

The herbicides, Tamariz (propanil + thiobencarb at 91/ha), Basagran PL2 (bentaz on

+ propanil at 81/ha) and Stam F34T (propanil + fenoprop at 9l/ha) produced

significant yield increases over the untreated check and were as effective as

two handweeding at 21 and 35 DT.

16

.

Tab

le 9

. E

ffec

t o

f N

ap

pli

cati

on

and

w

eed

con

tro

l m

etho

ds

on t

ota

l w

eed

wei

ght

and

gra

in y

ield

of

ROK

5 in

an

asso

ciat

ed n

angr

ove

swam

p at

Rok

upr

-19

87 s

easo

n.

To

tal

Wee

d C

ontr

ol M

etho

d o

kg N

/ha

Mea

n M

ean

One

ha

ndw

eedi

ng a

t 30

DT

13

.4

6.8

2

.5

7.6

2

.0

3.5

3

.8

3.1

Two

hand

wee

ding

s at

21

and

35

DT

3.9

1

.3

2.7

2

.6

2.5

3

.5

3.9

3

.3

Pro

pan

il

(9l/

ha)

at

21

DT

10

.3

6.3

1

1.4

9

.3

2.7

3

.6

3.8

3

.4

Pro

pan

il (

9l/

ha)

+

Ben

tazo

n (4

l/h

a)

at

21

DT

3.1

5.1

11 .

3 6

.5

3.1

3.7

4

.0

3.6

U

ntr

eate

d c

heck

3

0.4

3

7.9

26

.2

31.5

1

.5

2.0

2

.9

2.1

Mea

n 1

2.2

11

.5

7.0

')

2.

4 3

.3

3.7

...

,

L.S

.D.

0.05

Y

ield

W

eed

Wei

Jdlt

for

dif

fere

nce

s be

twee

n N

tre

ato

ent

nean

s =

0

.44

NS

L.S

.D.

0.05

fo

r d

iffe

ren

ces

betw

een

wee

ding

met

hod

Bea

ns

=

0.3

8

6.7

L.S

.D.

0.0

5

for

dif

fere

nce

s aB

ong

wee

ding

Bet

hods

fo

r th

e sa

ne N

tre

atB

ent

=

0.65

11

•. 6

L.S

.D.

0.05

fo

r d

iffe

ren

ces

betw

een

wee

ding

met

hods

fo

r d

iffe

ren

t N

tre

atm

ents

=

0

.73

1

0.6

C

. v.

(%)

(N tr

eatm

ents

) =

18

.3

95.5

C

.V.

(%)

(Wee

ding

met

hods

) =

1

4.6

70

.6

17.

Table 10. Effect of herbicides on weed control and yield of ROK 5

in an associated mangrove swamp at Rokupr.

Applic9.tion Treatment Rate

Tim~ ( l/ha)

Tamariz 9 20 DT Fb 1 hwat 30 DT

Tamariz 10 20 DT

Arozin D 2.5 10 DT Fb 1hw at 30 DT

Basagran PL 2 6 20 DT Fb 1 hw at 35 DT

Basagran PL 2 8 20 DT

Stam F34T 9 21 DT

Stam F34T 9 21 DT Fb lhw at 30 DT

Stam F34T 10 21 DT

Propanil + Bentazon 9 + 4 21 DT

Propanil + Bentazon 9 + 4 21 DT Fb 1hw at 35 DT

Handweeding 2 times 21 DT and 35 DT

Untreated Check

L.S.D. 0.05

C.V. (%)

11 DT = days after transplanting;

1hw = One handweeding.

Fb = followed by;

DISEASES

Weed weight ~dm2~

4.3

19.5

17.6

3.8

18.8

11 .6

1 .5

12.9 11 _ 8

3.5

2.6

44.6

18.9

87.9

Yield ( tons/ha)

3.4

2.4

2.7

2.3

3.0

3.0

3.0

2.5

2.5

2.5

3.0

1.7

1.0

22.6

Ecological studies of the 'white tip' nematode, Aphelenchoides besseyi

started in 1986 was continued this season to ascertain on the seriousness of

the problem. Riee blast , Pyricularia oryzae, brown spot, Cochliobolus

miyabeanus,and leaf scald, Monographella albescens are the key diseases already

identified. Crop management practices that minimize the incidence of br~wn

spot were formulated into an integrated pest management package and tested in

the field.

Disease Ecology

'White tip' nematod~

A study on the ~ccurrence ~f '~~ite tip' disease caused by the nematode

Aphelenchoides besseyi was initiated at Rokupr in 1986. Although 'White, tip'

symptoms have not been evidenced in the field for the last two seasons,

nematode infection was recorded at the panicle stage on ROK 5, 7, 8 and 9, SR 26 ,

and WAR 1 in 1986.

18.

The same observations). were made in 1987 and on Rohyb6-WAR-6-2-B-2. The level

of seed infestation observed in the previous season may warrant some

disinfestation of contaminated seeds in order to forestall the spread of the

pathogen.

Prototype Integrated Pest Management for Rice Diseases: In 1987, the packages

comprising (a) farmers' practice (his variety, method of raiSing seedlings

and transplanting, no fertilization and pest control), (b) Integrated Pest

Management (IPM) i.e. improved long duration cultivar (ROK 10) transplanting

of 6 week-old seedlings at 25 hills/m2 in early July, and application .f

N60P40 , and (c) IPM 2 i.e. IPM 1 plus fungicide spray at flowering/milk

~$~ of rice growth using tricyclazole (Beam) and Cupric hydroxide . " -.", - . -(Kocide 101) at 0.2 kg a.L/ha, respectively were compared at two locatiens.

In the Rokupr tidal mangrove swamp, the yields obtained were 2.4; 3.7

and 4.0 tons/ha for the fa~erst practice, IPM 1 and IPM 2, respectively.

Foliar brown spot incidence was not significantly different between packages.

The two IPM packages out yielded farmers' practice probably because of

improved crop management practices.

In the short season zone at Moribaia, the variety WAR 1 was used in the

IPM packages. On average, the farmer's practice yielded 0.6 t/ha as compared

to 2.5 t/ha and 3.5 t/ha for IPM 1 and 2, respectively. Brown spot incidence

was relatively high at the site. The swamps at Moribaia are saline, a

condition which predisposes the rice plant to severe attack by Q. miyabeanus

probably because of reduced plant vigour, The incidence of brown leaf spot

was reduced by 17.1 and 35.~ in IP~ 1 and IPM 2, respectively.

The low disease incidence in IPM 2 package and the consequent high grain

yield indicated that concomitant fungicide protection would be required in

the IPM package ~

INSECTS AND CRABS

Studies on the African white rice borer, Maliarpha separatella the most

predominant insect pest species focused on its seasonality in the rain-fed

upland rice nursery and monitoring of the adult moths in the sub-region by

sex pheromone. Grain yield losses in improved rice varieties attributable

to insect pests continued to be assessed under natural field infestation

while cultural means of pest control were investigated in order to develop

a cheap and effective integrated pest management strategy for the control of

the major insect pests and crabs.

19.

Ecological Studies of the African' White Rice Borer

Trials conducted on Maliarpha infestation of rice nurseries at Rokupr

indicated that the rice ?rop was attacked by this species as early as two

weeks after sowing in May/June (Figure 2). Farmers usually transplant eight

week-old seedlings in the Rokupr are, implying that they transplant infested

crop material in their rice swamps. No deadheart symptoms was evidenced in

the seedling crop attacked by Maliarpha inspi te of injury caused to the ::: , _.1::' i:-· .

seedlings. For effective control and management of this pest, crop protection

may therefore have to be initiated at the nursery stage.

Monitoring of the African White Rice Borer by Sex Pheromone

To develop an effective method of controlling Maliarpha, a dependable

means of monitoring needed to be devised, Through collaboration with the

Overseas Development Natural Resources Institute (ODNRI), the female sex

pheromone for this species has be~n identified, synthesized, field tested and

proven effective in attracting male Maliarpha moths. In 1987, the synthesized

lure was used region-wide for the first time to monitor field incidence of

Maliarpha moths in Sierra Leone, Guinea and Guinea-Bissau (Table 11). It is

apparent that the lure could be used to develop efficient trapping techniques

which can be used to monitor and suppress Maliarpha populations.

Insect Pest Infestation and Grain Yield Loss

Stem borer incidence on farmers' fields is usually high, ranging from

60 to 90% hill infestation. Under these levels of incidence in fields, rice

varieties are known to interact with insect pests differently. Improved rice

cultivars have therefore continued to be assessed under maximum insecticide

protection to ascertain on their levels of grain yield losses under fertilized

and unfertilize~ management practices to justify insect pest control action.

Table 11. Maliarpha male moth catches by sex pheromone in mangrove

swamp rice fields in Sierra Leone, Guinea and Guinea-Bissau

1987 season

Country Location Male .. moth catchesLmonth ( totalL!2 :trap~ June July Aug. Sept. Oct. Nov. Dec.

Sierra Leone Rokupr 0 0 3 9 56 200 233

Guinea Sonfonia 23 49 13*

Guinea-Bissau Bissau ~ 63**

* Catch for 3 weeks; ** Catch for 4 nights.

Nu

:-;:h

e-:'

3 2 1

1<'-

' f?

:-~

.

2 ·~::

·r

iJi

2

o ~ • ~

,,"P'"

~-O~

4 6

8 1

0

12

14

16

T

ime

aft

er

sC9

din

g

(Veek

s)

Incid

ence

o

f M

alia

rp

ha

s~pa

rate

lla

eg

3,

larv

s,

an

d

pu

pa

in rel~t

ion

:0 s

eed

lin

g a

ge

in rai

n~ed

up

lan

d ri

ce

nu

rse

ry

-R

oyu

pr

1987

.

20.

This season maximum crop protection commenced from the nursery stage

involving the improved varieties ROK 5, Rohyb6-WAR-6-2-B-2, WAR44-50-4-1,

WAR 1, WAR81-2-1-2 and ROK 10 under fertilized and unfertilized management

practices. WAR81-2-1-2, WAR 1 and ROK 5 (128-155 days) were most susceptible

to stem borer attack while ROK 10 (190 days) was most tolerant among test

varieties (Table 12). Maliarpha larvae beoomectess active feeders beginning

mid-October to early November which may possibly explain for the tolerance

observed in the long duration ROK 10 variety which matures in late December.

Generally, grain yield losses in the test varieties ranged from 23 to 40%

without fertilization and from 9 to 23% with fertilization. Fertilization

invigorated the crop and allowed it to tolerate pest attack better than the

unfertilized crop possibly through compensation.

Table 12. Average grain yield loss associated with stem borer

infestation in six improved rice varieties - Rokupr 1987.

Duration Percent Grain Percent Variety (days) stem yield yield

infestation (tons/ha) loss

WAR 81-2-1-2 128 5.7 c 2.5 c 39.9

WAR 1 147 5.9 c 3.4 a 23.3

ROK 5 155 5.6 c 3.3 a 25.7

WAR 44-50-4-1 165 8.3 b 3.3 a 35.3

Rohyb6-WAR-6-2-B-2 165 8.6 b 3.1 ab 25.5

ROK 10 190 10.6 a 2.8 b 28.0

Means followed by the same letter in the column are not significantly

different at 5% DMRT.

Insect Pest Control

Through ecological studies, the seasonality of the major stem borer

species lie saparatella, is now fRirly well known. Insecticidel control for

this and other insect pest species is de-emphasized because of high costs

and for both human and environmental considerations. Preliminary studies

have indicated that cultural practices influence to some extent insect pest

infestation of the rice crop. Early transplanting in July allowed the crop

to escape the peak of moth emergence thereby suffering less injury, while

transplanting at close spacing (25 hills/m2) has been shown to minimize stem

borer incidence in the field. Top priority was therefore given to the

manipulation of cultural practices to develop a cheap but effective system

of control for the major insect pests.

21 •

~ Various insect pest control tactics developed through cultural practices

were tested in combination as an rPM package in the field against the farmers'

practice. This season, the rPM package comprising of transplanting 42-day­

old seedlings at 25 hills/m2

in July, reduced stemboerincidence by 35% and

boosted grain yield by 16% when top dressed, with 80 kg N/ha urea over the

farmers' practice. Without fertilization, there was no significant difference

between the rPM package and the farmers' practice. Generally, crop

management by fertilization enhanced better crop performance in tolerating

inse.ct pest attack as also evidenced in the crop loss trial.

CRABS

Crabs continue to be serious pests of newly transplanted rice in most

ti~al mangrove swamp rice environments. Also, they are noted to burrow

through dikes and bunds and cause leakage of s a line water into empoldered

rice especially in Guinea-Bissau. Out of nine species presently recorded in

this environment, Sesarma huzardi, ~.alberti and Sarmatium curvatum are

partioularly destructive.. Sesarma huzardi is the most prevalent and voracious

species.

Crab Damage and Grain Yield Loss

Crab damage in tidal mangrove swamp rice fields is often heavier near

bunds and at the edges of rivers and creeks that drain these fields. At low

tides, crab intensities are higher at these sites. Weak seedlings (seedlings

raised on marginal soils and diseas e-infected seedlings) are most susceptible

to crab damage •

This season, preliminary studies undertaken to assess the impact of ~.

huzardi intensity and damage on grain yield of ROK 5 showed increasing grain

yield loss with increasing levels of crab intensity/m2 (Figure 3). Data

obtained indicated that as much as 34% loss in grain yield could be expected

from a 40% loss of crop stand due to crab damage.

Control and Management of Crabs

Tidal mangrove swamp rice farmers address severe crab problems in their

fields by transplanting very old seedlings (8 weeks old and over),

re-transplant devastated fields and in some instances deliberately delay

transplanting after uprooting rice seedlings from their upland rica nurseries.

These practices may not coincide with optimum agronomic requirements for the

rice crop. Re-transplanting one or two times in the season places undue

stress on the farmers' meagre resources.

f-

60

40

20

~

perc

en

t p

er

M

~

~ o

Dam

age

Gra

in Y

ield

Lo

ss

r---

~

~~~l

:;:; ~?

~ \.~:

.:.~.:

g-J

t~t.~

~~~~

~~?

~;;~ .. ~

(:~;~'t

~ '£:

..~

f~~~l

{i~~~

~f:

dh ::.

?'

~j2it:

:.....

!-.

t;;

~~ t~

~ ~01

~

~

-f-

.\ .~

~ .•

: \<

.~

)<'., ~I--

::;;:\ .. ,

'~ l~

~ ~

~'.

~.

~ j

~

~

~

~

~'<\

1,.'

.~~.

~

~

~

~\",...

!~~

';0'

~~

~':

~\

~'.:~

r~i

~~

,~

'" .;,-

.

~

~

~

?,....,

. 'l.

"" ..

:. ~.

_s

':...,$

., ..

~ t"':'

;

:;;-:

...: .~

. I'~,

.t;·,

t" ....

: '. ... :'

!

~

0 y

~

~~

,:0/

11-::;'

I.~!~

~

:..\.

.;..~

~

~

j ~

~

~

~

~

~

0 ~

~

'~1

~~~~

{.;.: ~~~

{

¥"

I·J·

. •

'"oJ:

-i:t

i..,l,

~./

.. :

.• :

.....

. ' 7.

'~'r

~.,

r~-,

u..:..'

.

'Y':?

,,

'. r.

;'

r}S~

1J}~

1 ',-

~ "'

:~

.. ~,..,

L!'

:1 :'~

? r~J

1 ;~

I

,~~

".--

.' '~:!1....J

o 7

1 U

21

28

".

. 2

Gra

b"J:

nte

ns:

J:i;Y

-'p

er-M

1i'1

.~ .

3.

'Tnr

oac-

t_o

L C~

,S .

i:r.

::0

stati

on

(S

esam

a h

uzard

i)

pe:!

:"M

2 O

!C

ROK

5 ~

ice

c:!:'

oj

.;,.

'1ok

'J:pr

19

87.

22.

The identification and determination of the role played by natural

enemies in regulating crab populations in tidal swamp rice fields are yet to

be determined. Meanwhile control of crabs making use of cultural practices

is given priority especially in the development of an IPM strategy •.

Prototype IPM for Crab Control: Earlier studies indicated that vigorous

seedlings and rice crop transplanted at close spacing (25 hills/m2) were

less attacked by crabs. These findings were incorporated into a single

control package (IPM package) this season and tested against the farmers'

practice in an area prone to severe crab problems. Farmers' practice involves

transplanting up to 32 seedlings of old and weak seedlings/hill at wide

spacing (12-16 hills/m2). Crab damage was significantly reduced in the

prototype IPM package and boosted yield by 40% over the farmers' practice at

one site prone to severe crab attack. In addition to minimizing crab damage

to the rice crop, the IPM package also imposes a saving in seedling coverage/m2

compared with the farmers' practice.

23 .

ON-F~i AND ADAPTIVE TRIALS

In order to ensure adaptability across environments, economic viability

and acceptability of improved technologies, trials continued to be carried out

across the sub-region especially for programs in varietal 'improvement and soil

and crop management.

EVOLVING NEVI VARIETIES

The variety improvement program tested improved varieties in collaboration

with NARS to select materials best suited to their needs.

MULTILOCATION TRIALS

FFTs: Three sets of six varieties each were tested in IDultilocation trials on

farmers' fields during 1987. The varieties were selected from previous

statiort trials that had shown potential for high grain yield.

The results of the medium duration FFTs grown at eight sites in the short

season swamps in Sierra Leone and Guinea are summarized in Table 13. WAR 1

significantly out yielded all test varieties except the new salt tolerant line,

WAR77-3-2-2. BG 400-1 which had performed well in station trials was also

out yielded by WAR77-3-2-2. BG 400-1 matured slightly later than the other

varieties, and this led to greater salt damage at saline sites. This resulted

in increased spikelet sterility compared to the earlier maturing varieties.

In two sets of long duration FFTs, no significant differences in yield

were found between Maung Nyo, Gbassin, Raden Jawa, WAR44-50-4-1, ROK 10 and

CP 4 grown at five sites, and between Rohyb6-WAR-6-2-B-2, WAR44-5-1-3,

WAR44-17-5-3, IR23429-R-WAR •. 1 and Kuatik Kundur a l so grown at five sites in

Sierra Leone and Guinea.

Table 13. Farmers' Field Trials of medium duration varieties

in Sierra Leone and Guinea - 1987 season.

Variety Nean yield ( tons/ha)

WAR 3.3 a

WAR 77-3-2-2 3.1 ab

Rohyb 4-1rlAR-1-3-B-2 2.7 b

ROK 5 2.0 ~

WAR 52-384-3-2 1.7 c

ROK 5 1.7 c

Means followed by the same letter in the column are not significantly

different at 5% DMRT.

C.V. (%) 17.8

24.

~: . To further evaluate and distribute germplasm to national Scientists,

two sets I'If AVTs each comp~tsirie,z of 14 test varieties were sent to 10

locations: Sierra Leone (2), Guinea (1), The Gambia (2), Guinea-Bissau (1),

Nigeria (2) and Senegal (2). Due to logistic problems, the trials in Guinea,

and The Gambia were not conducted and feedback on the trials in Senegal B;!ld

Nigeria is still pending.

In the medium duration AVT conducted at one location each in Sierra Leone

and Guinea-Bissau, average grain yields were 3.3 tons/ha at Rokupr and 3.7

tons/ha at Carboaanque in southern Guinea-Bissau. On average WAR 1,

Rohyb4-WAR-1-3-B-2, RD 15 and WAR 77-3-2-2 were the four top varieties, with

grain yields of 4.2, 4.0, 4.0 and 3,9 tons/ha, respectivelY, (Table 14). Days

to maturity of the test entries over the two locations ranged from 130 days in

WAR 49-14-2-1 to 156 days in Rohyb 1-1.

Table 14. Grain yield of the highest yielding entries in the region-wide

nedium duration advanced variety trials conducted in 1987.

Grain Yield (tons/ha) Mean Variety

Rokupr Carboxangue

(Sierra Leone)(Guinea-Bissau)

WAR 1 4.2 4.2 4.2

Rohyb4-WAR-1-3-B-2 3.6 4.3 4.0

RD 15 3.6 4.3 4.0

WAR 77-3-2-2 3.6 4.0 3.8

Grand Mean 3.3 3.7

C.V. (%) 14.6 13.74

L.S.D. (0.05) 0.8 1.0

In the long duration li.VT conducted in Sierra Leone average grain yield was

3.6 tons/ha. The three top varieties were SL 22-617, WAR 44-50-4-1 and

Rohyb6-WAR-6-2-B-2 with grain yields of 4 .2, 4 .1 tons/ha, respectively.

Rohyb6-WAR-6-2-B-2 had ranked among the top five varieties for four consecutive

seasons and was officially released in Sierra Leone in March 1988 and renamed

ROK 21.

25.

SOIL itND CROP MANAGEMENT

In collaboration with other institutions and farmers, promising new

technologies on fertilizer and Azolla identified on the Rokupr Station farm

were tested extensively on farmers' fields in Sierra Leone and Guinea.

Improving Nitrogen Use Efficiency on Farmers' Fields: Nitrogen is a major

limiting nutrient for rice cultivated in mangrove swamps. However, movement

of vast volumes of water under tidal influence and leaching make efficient

use of nitrogen in mangrove swamps difficult to accomplish. Several

approaches for increasing nitrogen use efficiency in mangrove swamps,

including split broadcast, point application and use of slow release forms of

nitrogen have been investigated.

Research undertaken at WARDA demonstrated that the method of application

is the most important factor influencing rice response to nitrogen in mangrove

swamps. Placement of 60 kg N/ha as an aqueous solution of urea at 20.ill soil

depth by the injection technique developed at vlilRDA - Rokupr showed a

potential for increasing yield of rice by a margin of 54-143% over the control

without nitrogen, as against increases of 17-70% when the fertilizer was

broadcast in a single dose. The injection technique had the advantage over

similarly effective three split broadcast procedures for nitrogen application,

in requiring only one application of nitrogen at the early ~~tative phase

of crop growth. This is well suited to the farming practice in mangrove SWaBpS

as farmers are relunctant to make more than one visit to their farms between

transplanting and harvest.

However, appropriate and easily adaptable technique for nitrogen

application in the mangrove swamp still needs to be developed. In 1987,

several methods of nitrogen fertilizer (60 kg/ha) ~pplication involving

broadcast and incorporation of prilled ure3. CPU) before transplanting;

broadcast of PU at 4 weeks after transplanting (1;vAT); and soil incorporation

(Point application) of urea supergramile (USG) at 4 WAT were evaluated for

grain yield responses under farmers' field conditions on the Scarcies.

Soil incorporation of USG resulted in the highest grain yield response

with yield increases of 1.5 tons/ha over the farmers' practice (Without

nitrogen) with a yield of 1.6 tons/ha of paddy (Figure 4). This increase

represented 3~ more in grain yield over basal incorporation of PU, which was

the most promiSing among the other methods of nitrogen application. Basal

incorporation of PU and broadcast PU at early tillering increased yield by

64% and 55%, respectively over the farmers' practice.

4

3

2

1

o

Grain Yield tons/ha

cv % =

c

z

Fig. 4.'

a

b

(53)

~ _L

• n·: H

fj 0 ()

s:: +-> H m

r-l 8 ctS U) (/) t) ctS < (l:\ (l:\

p P Pi Pi

of N (60 Kg/ha) applocation

Rice response to methods of N fertilizer application on farmers' fields - ;-!, c,'lY.'cicr; 19B?

.; .

( ) Percentage increase over con t rol

26.

To date, soil incorporation is the most effective means for increasing

nitrogen use efficiency in mangrove swamps. However, soil incorporation of

USG at 10-15cm by hand 'seemed a more arduous task than deep placement by the

injection technique. The potential of USG for increasing yield of rice under

the traditional broadcast application and basal incorporation procedures will

be evaluated in future trials.

On-farm Evaluation of Azolla: Trials were established on farmers' fiel ds in

inland and associated mangrove swamps in Sierra Leone and Guinea to assess the

potential of Azolla for rice cultivation.

Uncontrolled flooding, iron toxicity, phosphorus deficiency, and abscence

of adaptable strains of Azolla have been t he major constraints to utilization

of Azolla under farmers' conditions in humid tropical environments.

The Azolla strain ADUL 138 PP was identified as being widely adaptable to

these conditions in preliminary adaptation trials. In Sierra Leone, a biomass

of 1.71 kg FW/m2 , on average was obtained with cultivation of ADUL 138 PP

under farmers' conditions.

In 1987, cultivation of Azolla resulted in significant improvements in

grain yield of rice, producing similar yields of rice as the full complement

of mineral fertilizers (Table 15). Part of the response observed with Azolla

cultivation may be attributed to its effect on weed growth. Effective soil

incorporation of Azolla prior to transplanting was difficult to achieve on

farmers' fields. Allowing the unincorporated Azolla to intercrop with rice

resulted in the suppression of weed growth and probably accounted for the large

proportion of the grain yield response to Azolla cultivation.

Table 15. Grain yield and weed infestation of rice cultivated with Azolla

and mineral fertilizers on farmers' fields in Sierra Leone -

1987 season.

Treatlilenta

Control - without fertilizers

Mineral fertilizer N60P40K40

Azolla cultivation

Hean grain yield (t/ha)

1.3 b

2.2 a

2.1 a

Average* dry weed weiqht

(gLm2 )

411 .1

602.3

209.0

Heans followed by the same letter in the column are not

significantly different at 5% DMRT.

* Average over 7 sites

27.

The reduction of weed infestation in swamps with Azolla suggested that

labour time for weeding can be reduced considerably, especially in the

absence of an appropriate weed control technology. However, the difficulties

with water control on farmers' fields suggested that Azolla technology may be

appropriate only for swamps witll adequate water control systems.

22 ",

Adaptive Trials

Three components of improved technology packages involving (i) improved

varieties such as ROK 5, ROK 10, CP 4, Kuatik Kundur, \Hill 1, Rohyb6-~LI\R-6-2-B-2

(ii) application of '40 kg N/ha in the form of urea and (iii) mechanical land

preparation by using the single axle power tiller have been identified for

farmer managed trials in Sierra Leone, The Gambia and Guinea. Over the past

fi ve seasons the packages have been found to be successful under farme'r

management and are being adopted by farmers (Table 16). Improved varieties

that fit well in the farming system of most areas are being identified.

Table 16. Percent adoption of i mproved varieties by farmers in

the mangrove swamp rice environment of WARDA, 1978 to 1987.

I mproved variety Sierra Leone Guinea Gr. ScarciesNoribaya Satlu (Coyah,

Sonfonia) Kamsar

Guinea- The Bissau Gambia

ItOK 5 T.JTAR

]ohyb6-WAR-6-2-B-2

Rohyb4-1,IT AR-1 -3-B-2

Br 5191-6

Kuatik Kundur

ICuatik Hirang

Raden Mas

ROK 10

CP 4

50

*

17

35

90

*

* New adoption (cultivated by a few farmers)

+ Handled by seed Dultiplication unit.

30

* *

10

+ *+

*+

* 10

10

(Carboxque)

60

*+

*+

*+

*+

(South) Bank

+15-20

*

*

+

In 1987, packages involving i mproved varieties and fertilizers were

placed in tarmer managed trials at 8 locations each in tidal mangrove and

associated swamps in Sierra Leone, Guinea and The Gambia. In tidal mangrove

swamps, the package comprised WAR 1 and Rohyb6-WAR-6-2-B-2 in short and long

season areas, respectively plus top dressing of 60 kg N/ha of urea at early

tillering. The package in the associated swamps include 40 kg P20S/ha as

single superphosphate in addition to urea and Rohyb6-WAR-6-2-B-2 or KU,atik

Kundur. Data obtained are summarized in Table 17.

29.

Table 17. Performance of mangrove swamp rice technology packages,

under farmer management in Sierra Leone and Guinea, 1987.

Country and Zone

Sierra Leone

Balancera

Kychum

Mambolo

Guinea

Coyah

Yattaya/Sonfonia

Xattaya/Sonfonia

Grain yield (t!ha) Ecology New Farmers' Yield Additional Net benefit

TMS

TMS

AMS

AMS

TMS

AMS

Technology Practice Gap input cost due to new (tZha) technology

2.957

2~873

7."96

2,917

2.426

3.381

2.557*

2.206*

1 .701

2.027

1.850

2.456**

0.400

0.667

1.595

0.890

0.606

0.925

Leones Leones

822.30 2,Cf57.70

822.30 3,980.10

2,917.60 9,842.40

QE QE

55,849 10,901

21,422 24.028

49,628 19,747

TMS = Tidal Mangrove Swamp

AMS = Non-tidal Mangrove Associated Swamp

New Technology - TMS = Improved variety + Urea (60 kg N/ha)

AMS = Improved variety + Urea (60 kg N/ha) and SSP

(40 kg P 205/ha).

Farmers' Practice - Local variety only.

(* Adoption of improved varieties by large number of famers)

(** Local variety with better adaptation to soil stresses)

-1 Labour cost day Sierra Leone = UQ5.30

Guinea: Coyah, GF 687; Yattaya, = GF 493.8

t -1 Fer ilzer cost kg

-1 Paddy Price kg

~ONES

Sierra Leone

Balancera

Kychum

Mambolo

Guinea

Coyah

NPK 1 5 :1 5 : 1 5

1e3.80

3.80

3.20

GF145

Yattaya/Sonfonia GF132.5

Sierra Leone Leones

Balancera 7.20

Kychum 7.20

Mambolo 8.00

LE4.00

4.00

3.90

GF120

GF120

Guinea

Coyah

Yattaya/ sonfonia

UQ.80

2.80

2.80

GF125.0

GF125.0

QE

75

75

30.

Sierra Leone: In the tidal mangrove swamps. of Balancera (short season zone)

and Kychum (medium season zone) along the great Scarcies, most of the

co-operating farmers have adopted improved rice varieties. This accounted

for the comparatively high yields obtained even with the farmers' practice

in these areas. The yield gap between the farmers' practice and the new

technology ranged from 0.40 to 0.67 tons/ha. In the associated mangrove swamp

in the Mambolo area (medium season zone) Kuatik Kundur out yielded the farmers'

practice by a yield gap of 1.6 tons/ha. Consequently, higher returns were

realized from the improved package with net benefits in the range of U2000 -

1.e10,000/ha.

This is the third season lillli 1 has performed well in adaptive trials in

the Balancera zone and would seem well suited for this area. In the Kychum

and Mambolo area, Kuatik Kundur may be promising material.

Demonstrations: The package of ROK 10 plus urea (60 kg N/ha) placed in long

duration areas, out yielded farmers' practice by 21.2 and 24.~ on the Scarcies

and along the BUL1peh in northwest and southwestern regions of Sierra Leone,

respectively.

Guinea: Wt~ 1 and Rohyb6-WAR-6-2-B-2 performed well both in the tidal and

associated mangrove swamps in the Yattaya area with a yield gap range of 0.61 to

0.93 tons/ha. The improved package carried an additional input cost of

GF 21,422 to GF49,628 but brought in a net benefit of GF19,747 to GF24,028/ha.

In the Coyah zone, the improved package comprising of Rohyb6-WAR-6-2-D-2

yielded significantly higher than the farmers' practice but had a lower net

benefit o~ GF10,901. In the Coyah zone, input costs were higher than in the

Yattaya/Sonfonia zone.

Seed Multiplication and Distribution

To assist in the availability and spread of improved varieties, the

station has been multiplying and distributing small quantities of seeds of

improved varieties/advanced lines to scientists and extension workers in the

region. Since 1985, a total of 1.1 tons of breeder seeds of 54 recommended

and promising lines; and 1.0 ton of improved seeds of seven varieties

(ROK 10, CP 4, Kuatik Kundur, ADNY 301, Rohyb6-VIAR-6-2-B-2, ROK 5, and WAR 1)

have been produced.

In collaboration with the Northwestern Integrated Rural Development

Projwct (NWIADP) in Sierra Leone, 15 tons ' ~ee varieties (ROK 5, ADNY 301

and ROK 10) are being made available for d_ .oution to over three hundred

mangrove swamp rice farmers in Northwest and Southwest Sierra Leone in 1988.

The seeds will be recovered at harvest for further distribution to more

farmers in 1989.

31.

INTERNATIONAL AND NATIONAL CO-OPERATION

The station worked in close partnership with some international

agricultural research cent~rs and developed strong linkages and cooperation

~~~~ ~a~tonal agricultural research systems (NARS) to help them utilize

improved rice technologies in the \,lARDA sub-region.

A. Cooperation with International Institutions

Since its inception, this station has collaborated actively with IRRI

and has tested over 6,000 lines from several IRTP nurseries. Several of

these lines have shown promise on the basis of soil stress tolerance, plant

type, grain yield and seed characteristics. In 1985, the station made

available to IRRI ROK 5, ROK 10, and CP 4 for somaclonal varietal studies and

produced 17 variants. These are currently being tested for tolerance to

various enviror~ental and biological stresses and adaptation to the nangrove

rice conditions in the sub-region. This station also acti~1y collaborate:d::

with IITA in a netwDrk of varietal screening activity for iron toxicity in the

1-JARDA region.

In collaboration with ODNRI the ·female sex pheromone of li. seaparatella

the predominant stem borer pest has for the first time been identified and

synthesized. The pheromone was deployed for region-wide monitoring of

Maliarpha in the sub-region and elsewhere.

B. Cooperation with National Institutions

Member states of the region differ in their needs and capabilities for

research. We tlS·OO c);i;a ted; ourselved with NARS to respond to the precise

needs of any particular country. This partnership has facilitated the

rapid spread of improved rice varieties among mangrove swamp rice farmers in

the region. In Sierra Leone, we have developed a close and strong working

relationship between our station and the National Rice Research Station (RRS).

vi e co-operate with RRS in planning research activity, exchanging and testing

promiSing varieties. A breeding program on resistance to RYMV has been

initiated in collaboration with RRS.

''Te held joint monthly seminars with RRS uhere Scientists alternated in

making presentations. Our collaborative effort strengthened field days and

training courses for field assistant and extension workers organized by RRS.

In 1987, our station participated fully in the annual field-day activities

organized by RRS at Rokupr, and displayed charts and photographs of relevant

research findings.

32.

We have collaborated with other agricultural institutions like the seed

mul tiplication project, Bo-Pujehun Rural Develo"pment Project and t !le Bayande

Snall Farm Development Project in supplying promising varieties such as WAR 1,

Rohyb6-\vAR-6-2-B-2 and Kuatik Kundur or g i ven assistance to these Projects in

the identification, selection, and testing of Azolla as a bio-fertilizer.

Both our station and NWIADP have jointly planned seasonal field activity and

carried out on-farm demonstrations of i TIproved technology in northwest

Sierra Leone.

In Guinea, partnership with the Ministry of Agriculture has led to the

secondment of their field staff to enhancG opportunity for continuous and

effective participation of on-going collaborative activity. Through

researcher managed pre-extension and adaptive trials conducted at multiloca­

tions "TAR 1, Rohyb6-vlAR-6-2-B-2, Kuatik Kundur, Kuda Hirang and Raden Nas have

Gained acceptance by mangrove swamp rice farmers in the Sonfonia and Coyah

regions in preference to their traditional varieties. Over 5 ha in Coyah

region alone was under multiplication of these varieties in 1987.

In The Gambia, like in Guinea, we plan with the Ninistry of Agriculture

and provided logistic support to field staff to supervise our collaborative

activities. "In cooperation with the Freedom from Hunger Campaign (FFHC)

Project and the Ministry of Agriculture, several adaptive trials of improved

packages were carried out at several sites. By this,ROK 5 ga.ined popularity

and is now" widely cultivated in t]~ e country. Three other varieties, VliLT-?. 1,

Rohyb6-'IlAR-6-2-B-2 and Kuatik Kundur have been identified by the Ninistry of

Agriculture for demonstration in 1988 and for further multiplication.

Over 400 WARDA varieties have been tested in Guinea-Bissau in collaboration

wi th the Ninistry of Agriculture and ILural Development (DEPA). Of these, viAll. 1,

Rohyb6-WAR-6-2-B-2, Rohyb4-vJAR-1-3-B-2 and BR5191-6 have been considered for

release. ROK 5, the most widely grown variety was made popular by WARDA

through its coordinated variety trials in the early 1980's.

The research team at Djibelor in t he CaS8LlanCe (southern Senegal) has

made some selections from the breeding populations supplied them by. our

station since 1983.

In Nigeria, a procram has been des it",'ned to develop collaboration 'vi th the

National Cereals Research Inst j.tute in testing and eval uating Ilromising

varieties/advanced lines in regional advanced variety trials.

Within the next two cropping seasons, this station will "work in closer

partnership vTi th NARS in identifying , planning and carrying our research

strategies in areas of concern 1tT i th t he aim of strene,-thening national

research capabilities.

33.

:.r,RA.1 N 1 U G

WARDA - Rokupr oontinued t o strengthen t he man-power resources of NARS in

the areas of rice research, development and production. This was

accomplished through various trai ning activities in rice research and

production methodologies ineluding training of ~mdergraduates, young scientists

and technicians. Exchnnge visits with Nlu'tS staff .. Tas also an integral part of

the Station's training activities.

Deg;ree-~~J..{l.te<! T.r~,iu.t~=- Students enrolled at accredited uni versi ties \,li thin

and outside the region conducted t heir research at t he Station under the

guidance and supervision of station scientists. The selected areas of

researoh were within the scope of the Station's research mandate, and served

to train the students and young scientists in rice research methodologies.

As at 1987, a total of 34 students and scientists have conducted their

researoh at the Station as shown in Table 18.

In 1987 tl'lo B.Sc. students from Njala University worked on the following

dessertat10ns under collaborative supervision of Station Scientists and

University lecturers.

(i) Potential of Azolla s pecies as source of nitrogen for rice.

(1i) Impact of crab damage on grain yield of rice.

Table 18. Students supervised and/or supported by WARDA - Rokupr

for degree-related progra ,. 1977 - 1987.

-----,--------,---- ,--------.~.---,,-

Country University B.Sc. M.Sc. Ph.D. Total . --- -- ---

Britain Reading 4 4

West GerLlany Justus/Liebig

Cameroon Sierra Leone

Sierra Leone Birmingharu 1

Sierra Leone Sierra Leone 24 2 27 ------ - - - ._- _.-TOTAL 25 7 2 34

34.

1987 PUBLICATIONS

1. Agyen-Sarnpong,H. (1987). Assessment of on-far.n losGes in rice due

to insect pests. Paper presented the Regional Study Workshop

on On-farm and Post-harvest Losses of Cereal Crops in Africa

due to p 'ests and Diseases. ICIPE, Mbita Point, Kenya,

October 11-15, 1987.

2. Agyen-Sarnpong,M. and Fannah, SoJ. (1987). Seasonality of the vlhite

borer, Maliarpha separatella Rag. (Lep idoptera: Pyralidae)

in mangrove swamp rice ecology of northwest Sierra Leone.

\JARDA Technical Newsletter 1 (1): 4-6.

30 Akinsola,E.A o and Agyen-Srunpong,M. (1987). Irriga ted rice pest

control in v/est Africa.Paper presented c.t the International

Rice Research Conference, Hangzahou, China, September 21-25,

1987.

40 Bangura,FoJo, Jones,M.P. and Bernard,H.M. (1987). Deep flooded

rice growing areas near Tormabum, Sierra Leone. Deep Water

Rice E : 3-6.

Bernard,H.M. (1987). The biogology and control of Paspalum .. . -e .

vaginatum (Swo) a weed destructive to mangrove swamp rice in

Sierra Leone.. H.Sc. Thesis, University of Sierra Leone. 98po

60 Cork,Aoand Agyen-Sarnpong,Mo (1987)0 Sex pheromone of the white

rice stemborer, !ialiarpha separatella. Paper presented at

the 4th Annual Heeting of the International Society of

Chemical Ecology. University of Hull, Englru1d, July 13-17,

1987.

7. Dixon,C.A. and Agyen-Sampong,M. (1987). On-farm research at WARDA-

Rokupr. Paper presented at the VJorkshop on On-farm Research

in Sierra Leone. Njala University College, Sierra Leone,

November 23-25, 1987.

8. Fannah,SoJo (1987). Elophila sp. ? africalis Hwnpson (Lepidoptera:

Pyralidae): A new pest of Azolla in Sierra Leone. International

Rice Research Newsletter ~ (3): 300

9. Fomba,SoN. (1987). Promising fungicides for the control of seertling

blast, Pyricularia oryzae Cav. in upland rice nursery in

Sierra Leone. VJARDA Technical Newsletter 7 (1): 14-15.

10. FOinba,S.N. (1987). The ecological role of ~!~~i_o~~~?. ~iyabeanus

(Ito et Kuribayashi) Drechsler ex Dastur in reducing rice yielrts

in mangrove swamps of Sierra Leone. Ph.D .. 'l'hesis, University

of Sierra Leone. 235p.

11. Jones,MoP. (1987). Nain and ratoon rice crop performance in mangrove

swamps. International Rice Research Newsletter ~ (2) : 11-12.

12. Jones,M.P. and Agyen-Sampong,M. (1987). The current status of varietal

improvement in mangrove swamp rice. Paper presented at the

vlorkshop on IRTP-Africa, st. Louis, Senegal, October 14-16,1987"

13. Jones,M.Po (1987). Screening mangrove swamp rice varieties for salinity

tolerance. Paper presented at the vJorkshop on IRTP-Africa, St.

Louis, Senegal, October 14-16, 1987.

36.

PERSONNEL

R ESEATICH STAFF Po.SITION

H. Agyen-Sampong Ph.D. Entomolo[::i ,s t/Bta hon Director

N. P. Jones Ph.D. Associa t e Br ·3eder

s. N. Fomba Ph.D.

C. Ao Dixon HoSe. Ass ocia t e E>o:i.l Scientist

s. J. Fa,nnah H.Sc. Associate En toL1clogist

H. H. Bernard MoSe. Associate \Teed S cienti.s~

SUPPORTING ;)Tt'\FF ..... _' ... _----'.-------s . Kamara B .. Sc.. (Hons.) Admin. As;3t./Fin. Officer

M. S. Sufi A.li HND. Supervisor

26 Field Assi.stant/Clerks/Drivers

60 La bourers/l1'a tchmen/N e ssengers