Estimates of Combining Ability and Heterosis for Yield and Its … · 2019. 7. 30. ·...

Research ArticleEstimates of Combining Ability and Heterosis for Yield and ItsRelated Traits in Pearl Millet Inbred Lines under Downy MildewPrevalent Areas of Senegal

Ghislain Kanfany 123 Amadou Fofana3 Pangirayi Tongoona1 Agyemang Danquah1

Samuel Offei1 Eric Danquah1 and Ndiaga Cisse2

1West Africa Centre for Crop Improvement University of Ghana PMB LG 30 Legon Ghana2Centre drsquoEtudes Regional pour lrsquoAmelioration de lrsquoAdaptation a la Secheresse BP 3320 Thies Senegal3Centre National de Recherches Agronomiques de Bambey BP 211 Bambey Senegal

Correspondence should be addressed to Ghislain Kanfany gkanfanywacciedugh

Received 11 December 2017 Accepted 22 March 2018 Published 2 May 2018

Academic Editor Iskender Tiryaki

Copyright copy 2018 Ghislain Kanfany et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Pearl millet is an important cereal crop for smallholder farmersrsquo food security in West and Central Africa However its productionhas stagnated due to several factors such as the continuous use of local populations A set of 17 inbred lines was crossed with SosatC 88 and Souna 3 following a line times tester mating design The 1198651 hybrids their parents and a check were evaluated in Bambeyand Nioro research stations during the rainy season of 2017 Data on downy mildew incidence plant height flowering time paniclelength and diameter productive tillers thousand-grain weight panicle and grain yield were recorded GCA and SCAmean squareswere significant for most of the traits indicating that both additive and nonadditive gene effects were involved in the control of theinheritance of these traits However the contribution of GCA to total mean squares was higher than that of SCA for all the traitsproviding that additive gene action wasmore important in their inheritanceThe top-cross hybrid IBL155-2-1 times Sosat C 88 exhibitednegative and significant SCA effects for downy mildew incidence flowering time and plant height Lines IBL003-B-1 IBL091-1-1IBL095-4-1 IBL110-B-1 and IBL 206-1-1 had positive GCA effects for grain yield and negative GCA effects for downy mildewflowering time and plant height These lines can be used as parents to create synthetic varieties or hybrids

1 Introduction

Pearl millet (Pennisetum glaucum (L) R Brown) is the 4thmost important tropical cereal after rice maize and sorghum[1] In 2014 global grain pearl millet production was esti-mated at 28 million tons harvested from 32 million hain Asia Africa and the Americas The average yield isabout 900 kg haminus1 India and Africa are the most importantproducers withmore than 85 of the total production in 2016[1] It is an important dual purpose cereal crop in Africa andAsia where it is considered as a staple food and source offodder and feed for livestock for smallholders farmers [2]Thegrain of pearl millet is a very rich source of protein vitaminsand minerals in comparison with other cereals and is usedfor human consumption in diverse ways [3] The pearl millet

stover is used as fuel material for building and fencing andalso a soil additive to enhance soil fertility [4] It is also beingexperimented as a grain and forage crop in the USA CanadaMexico India and West and North Africa [5]

As the world population is continuously increasing andis projected to reach nine billion by 2050 pearl millet isexpected to play an important role for achieving food securityin West and Central African countries which have thehighest population growth rates in the world [6] Howeverin this part of the world yields of pearl millet are verylow compared to yields in India and yet African farmersparticularly in Senegal have not adopted improved varietiesin a large scale In pearl millet growing areas in Africaadoption rate of improved OPVs varied from 5 to 37 [7] Incontrast most Indian farmers are using improved varieties

HindawiInternational Journal of AgronomyVolume 2018 Article ID 3439090 12 pageshttpsdoiorg10115520183439090

2 International Journal of Agronomy

particularly hybrids since the 1960s Indeed in India hybridshad 25ndash30 grain yield advantage over OPVs leading tothe rapid adoption of the hybrids whose yield increasedfrom 305 kg haminus1 during 1951ndash1955 to 998 kg haminus1 during2008ndash2012 [5] Thus enhancement of pearl millet produc-tion and productivity in Africa which is a high prioritycan be achieved through the identification of elite parentmaterials which can be used as parents to develop hybridvarieties

ICRISAT has developed pearl millet inbred lines derivedfrom landraces originating from West and Central Africawhich can be useful in developing high yielding pearl millethybrids and synthetic varieties with considerable adaptationto this pearl millet growing environment These lines werescreened for pearl millet downy mildew resistance in Senegaland some of them showed good agronomic traits and resis-tance to the pearl millet downy mildew However the perse performance of these pearl millet inbred lines does notpredict the performance of hybrids for disease resistance andagronomic traits [8]Therefore to make effective use of thesepearl millet inbred lines their combining abilities need tobe elucidated [9] This genetic information can be obtainedby different mating design including line times tester [10] GCAand SCA estimates of pearl millet inbred parents or landracesfor different traits such as micronutrients [11] grain quality[12] and fodder yield [13] were reported to be importantAdditive genetic action was also reported to be importantin controlling traits such as grain yield flowering time andpanicle length [14] There is scanty published informationon the combining ability of the pearl millet inbred linesderived from landraces collected in West and Central Africaknown as the origin of the crop for disease resistance andagronomic traitsThe objectives of this study were to estimatecombining ability and heterosis of pearl millet inbred linesfor downy mildew yield and other agronomic traits underdowny mildew infested fields and identify superior pearlmillet hybrids for yield yield components and resistance todowny mildew

2 Materials and Methods

21 PlantMaterial andMatingDesign Seventeen inbred lineswere used as females and crossed each to two OPVs usedas males according to the line times tester mating design [10] togenerate 34 1198651 hybrids The OPVs varieties were consideredas testers and the inbred lines as lines The two testers namedSouna 3 and Sosat C 88 are popular varieties adapted to thegroundnut agroecological zone The pearl millet inbred linesused for the study were selected from a pool of pearl milletlandraces from West and Central Africa converted to inbredlines through successive selfing up to S6 [15] These inbredlines were selected through a downy mildew phenotypicevaluation conducted at Bambey and Nioro research stationsduring the rainy season 2016 They showed less than 10DMI and were classified as resistant varieties The seeds ofthe male parents were planted in 4 different dates in orderto synchronise the flowering time of these male parents withthe ones of the female parents Thus from January 2017 thesowing of the male parents was done every week and seeds of

each of the male parents were sown in 5 rows of 15 hills perrow All the female parents were sown in one time during thesecond sowing date of the male parents in a one row-plot of15 hills At the booting stage at least plant heads of 4 paniclesper plant of the male and female parents were covered inorder to avoid undesirable pollination At flowering eachcovered panicle of female plant was pollinated with bulkpollen collected from at least 20 different plants of the maleparent

At maturity stage 1198651 panicles of the female parents wereharvested and the lower and upper parts of each panicle werecut before threshing to minimize outcrossing from unknownplants or selfing Indeed because of the protogynous natureof the crop the stigmata of a plant are receptive before theshedding of pollen and the flowering starts from the upperto the lower part Then the upper part of the panicle may bepollinated by unknown plants if not covered on the right timeand the lower part of the panicle may be pollinated by thepollen from the same plant

After threshing 1198651 seeds from the same female parentwere bulked and used as 1198651 hybrids The 34 1198651 hybrids alongwith the 17 inbred lines the two testers and an OPV namedThialack II as check providing 54 genotypes were used forthe evaluation (Table 1)

22 Study Sites Experimental Design and Field ManagementThe 34 hybrids together with their parents and the OPVcheck were evaluated under rainfed conditions during therainy season of 2017 at two locations in Senegal The studysites were Bambey (13∘4910158401210158401015840 North 13∘5510158401210158401015840 West) andNioro (13∘451015840010158401015840 North 15∘481015840010158401015840 West) research stationsBoth locations are in the groundnut agroecological zonethe main pearl millet growing area in Senegal and werecharacterized as hotspots for downy mildew in the previousstudy The genotypes were arranged in 9 times 6 alpha latticedesign with three replications at each site Each block wassurrounded by a downy mildew infector row consisting of adowny mildew susceptible line 7042 S sown 3 weeks beforethe tested materials Each plot consisted of one row of 81mlength with a spacing of 09m between rows and betweenplants within a row At least 10 seeds were planted per holeand later thinned to two plants two weeks after sowing Thefields were weeded two times after sowingThe trials receivedthe recommended 15N-15P-15K basal fertilizer at a rate of150 kg haminus1 just before sowing During the crop developmenta top dressing using area at a rate of 100 kg haminus1 was done intwo fractions 50 kg haminus1 after thinning and 50 kg haminus1 afterthe second weeding

23 Data Collection The recorded data were collectedaccording to the method described by Drabo [14] Flowering(FWT) was recorded by counting the total number of daysfrom sowing to the time when 50 of plants in a plotflowered Downy mildew incidence (DMI) was obtained bydividing the total number of infected plants 30 DAS from aplot by the total number of plants Panicles harvested in aplot were weighed to determine panicle yield (PY) and thenthreshedGrains obtained in each plotwereweighed andused

International Journal of Agronomy 3

Table 1 List of parental lines and check used in the study

Number Genotype Source Role in crosses Status Response to downy mildew1 IBL 001-4-1 ICRISAT Line Inbred line Resistant2 IBL 003-B-1 ICRISAT Line Inbred line Resistant3 IBL 011-4-1 ICRISAT Line Inbred line Resistant4 IBL 021-3-1 ICRISAT Line Inbred line Resistant5 IBL 055-4-1 ICRISAT Line Inbred line Resistant6 IBL 091-1-1 ICRISAT Line Inbred line Resistant7 IBL 095-4-1 ICRISAT Line Inbred line Resistant8 IBL 098-3-1 ICRISAT Line Inbred line Resistant9 IBL 106-B-1 ICRISAT Line Inbred line Resistant10 IBL 110-B-1 ICRISAT Line Inbred line Resistant11 IBL 114-6-1 ICRISAT Line Inbred line Resistant12 IBL 119-B-1 ICRISAT Line Inbred line Resistant13 IBL 155-2-1 ICRISAT Line Inbred line Resistant14 IBL 165-1-1 ICRISAT Line Inbred line Resistant15 IBL 179-2-1 ICRISAT Line Inbred line Resistant16 IBL 179-3-1 ICRISAT Line Inbred line Resistant17 IBL 206-1-1 ICRISAT Line Inbred line Resistant18 Souna 3 Senegal Tester OPV (improved) Susceptible19 Sosat C 88 Senegal Tester OPV (improved) Resistant20 Thialack II Senegal Check OPV (improved) Susceptible

to calculate grain yield (GY) in kg haminus1 using the followingformula

GY (kg haminus1)= [ grain weight (kg plotminus1) times 10000

plot size m2] (1)

Five random plants were selected in each plot to measure theplant height (PH) from the base of the plant to the upper partof the panicle number of productive tillers (PT) by countingthe number of tillers per plant which produce productivepanicles panicle length (PL) and panicle diameter (PDIA)Five random samples of 1000 grains for each plot wereweighed using a sensitive balance to determine the 1000-grainweight (TGW)

24 Data Analysis Analysis of variance for each experimen-tal site as well as for combined data after the homogeneitytest of variance across the two experimental sites was per-formed using the general linear model (GLM) procedurein SAS version 94 (SAS Institute Cary NC) The followingmathematical linear model was used

119884119894119895119896 = 120583 + 119866119894 + 119871119895 + GL119894119895 + 119903119895119896 + 119887119895119896 + 119890119894119895119896 (2)

where

119884119894119895119896 is the observed value of the variable for the 119894thentry in the 119895th location within 119896th replication120583 is the overall general mean

119866119894 is the effect of the 119894th genotype119871119895 is the effect of the 119895th locationGL119894119895 is the interaction effect of the 119894th entry and the119895th location119903119895119896 is the effect of the 119896th replication within the 119895thlocation119887119895119896 is the effect of the 119897th block of the 119896th replicationin the 119895th location119890119894119895119896119903 is the experimental pooled error

For the combining ability analysis of variance was performedfor traits that showed significant differences among hybridsusing SAS software version 94 (SAS Institute Cary NC)Thus the sum of squares of hybrids was partitioned intovarious variations due to lines testers and their interactionsbased on the following statistical model described by Singhand Chaudhary (1977)

119884119894119895119896 = 120583 +119872119894 + 119865119895 +MF119894119895 + 119890119894119895119896 (3)

where

119884119894119895119896 is 119896th observation on the 119894th and 119895th progeny120583 is the overall general mean119872119894 is the effect of the 119894th male119865119895 is the effect of the 119895th femaleMF119894119895 is interaction effect119890119894119895119896 is error associated with each observation


Table 2 Mean squares for studied traits across locations

Source of variation df DMI FWT PH PL PDIA PT TGW PY GYRep (site) 4 2324lowastlowast 284lowastlowast 7464 285 04 22 49lowast 2499694lowast 1258762lowastlowast

Block (Rep times site) 48 855 82 3599 329 014 15 23 817310 324630Site 1 846 2489lowastlowastlowast 01 4441lowastlowast 16lowastlowast 294lowastlowast 362lowastlowastlowast 5279671lowast 3168503lowastlowast

Genotype 53 1564lowastlowastlowast 823lowastlowastlowast 31935lowastlowastlowast 2786lowastlowastlowast 046lowastlowastlowast 51lowastlowastlowast 104lowastlowastlowast 3975982lowastlowastlowast 1157443lowastlowastlowast

Genotype times site 53 727 1362lowastlowast 4881 451 019 20 24lowast 1418904lowast 603031lowastlowast

Error 164 6004 79 4747 316 017 19 16 997156 297217DMI downy mildew incidence FWT flowering time PH plant height PL panicle length PDIA panicle diameter PT productive tillers TGW 1000-grainweight PY panicle yield GY grain yield df degree of freedom Rep replication lowastlowastlowastlowastlowastlowastSignificant at 005 and 001 and 0001 probability levels respectively

The values of the general combining ability for bothmale andfemale and the specific combining ability effects for all thestudied traits were estimated as follows

GCALine = Line mean (119883119894)minusOverall mean (119883 )

GCAtester = Tester mean (119883119895)minusOverall mean (119883 )

SCAlinetimestester = Cross mean (119883119894119895) minus Line mean (119883119894)minus Tester mean (119883119895)+Overall mean (119883 )

(4)

where

119883 is overall mean119883119894 is mean of all the hybrids containing an 119894th lineaverage over all replications sites and males119883119895 is mean of all the hybrids containing a 119895th testeraverage over all replications sites and females119883119894119895 is mean of the cross between 119894th line and 119895th testeracross all replications and sites

The significance of the GCA effects was tested using theformula described by Cox and Frey (1984)

119905cal = GCASEgca (male)

where SE(gca male) = radicMe119903119905119904119905cal = GCA

SEgca (female) where SE(gca female) = radicMe119903119905119904

119905cal = SCASESCA (linetimestester)

where SE (sca) = radicMe119903119904

(5)

where

Me is the error mean sum of squaresr t l s are numbers of replications testers lines andsites respectivelySE is standard error

Standard mid-parent and better parent heterosis for grainyield were also calculated for each cross across locationsfollowing Hallauer et al (2010)

Standard heterosis (SH) = (1198651 minus Check)Check

times 100Mid-parent heterosis (MPH) = (1198651 minusMP)

MPtimes 100

Better parent heterosis (BPH) = (1198651 minusHP)HPtimes 100

(6)

where 1198651 denotes the mean performance of the hybridaveraged over the two locations The mean value of theOPV check was used to calculate the standard heterosisThe parent with the highest mean value was used as betterparent in the calculation of high-parent heterosis while theaverage between the two parents was used for the mid-parentheterosis

3 Results

31 Performance of Hybrids and Parents across LocationsCombined analysis of variance across locations showedhighly significant (119875 lt 001) genotype effect for all measuredtraits (Table 2) Site effect was also significant for all the traitsexcept for DMI and PH However interaction genotype times siteeffect was only significant for FWT TGW PY and GY

All genotypes were resistant to downy mildew with amean DMI of 4 except for IBL 155-2-1 and its progeny withSouna 3 which displayed both 22DMI (Table 3) Days fromsowing to 50 flowering (DAS) of genotypes across the twosites ranged from 50 to 69 DAS with an average of 56 DASThe genotypes were tall with plant height ranging from 2 to32m Panicle length of the pearlmillet genotypes varied from27 to 58 cm with an average of 44 cm while their diameterranged from 12 to 27 cm with a mean diameter of 21 cmThe number of productive tillers ranged from 2 to 6 tillersper plant with a mean value of 4 productive tillers per plantThe 1000 seeds weight varied from 5 to 12 g with a mean of9 g The panicle yield of genotypes across the two sites variedfrom 376 kg haminus1 for IBL 119-B-1 to 4190 kg haminus1 for IBL 110-B-1 times Souna 3 and their grain yield varied from 92 kg haminus1 forIBL 119-B-1 to 2024 kg haminus1 for IBL 206-1-1 times Souna 3

As expected the 1198651 hybrids were generally more produc-tive compared to the inbred lines and OPVs The top five


Table 3 Performance of tested genotypes for studied traits across sites

Genotype DMI FWT PHIG PLEN PDIA PT TGW PY GYIBL 001-4-1 2 60 255 34 21 2 10 1104 585IBL 003-B-1 4 51 231 31 25 5 11 1872 1340IBL 011-4-1 14 59 237 44 19 3 7 1164 428IBL 021-3-1 0 63 223 32 21 2 8 1178 419IBL 055-4-1 6 65 210 37 16 2 6 517 286IBL 091-1-1 0 60 246 47 22 4 8 2328 1136IBL 095-4-1 0 50 243 37 19 5 10 2015 947IBL 098-3-1 11 51 239 31 18 4 10 1946 1188IBL 106-B-1 6 54 278 39 18 3 10 1340 710IBL 110-B-1 0 62 240 45 16 2 6 997 404IBL 114-6-1 0 62 199 27 18 2 8 750 324IBL 119-B-1 0 69 260 41 12 2 5 376 92IBL 155-2-1 22 57 200 35 13 3 7 1099 466IBL 165-1-1 2 64 238 39 16 4 7 1349 489IBL 179-2-1 0 60 272 43 19 2 8 850 394IBL 179-3-1 8 54 233 35 20 5 8 1497 886IBL 206-1-1 0 56 228 38 18 4 8 2102 1126IBL 001-4-1 times Souna 3 17 53 273 43 20 5 11 3475 1923IBL 003-B-1 times Souna 3 8 52 259 44 21 4 9 3218 1646IBL 011-4-1 times Souna 3 5 52 255 50 18 4 8 2368 942IBL 021-3-1 times Souna 3 4 57 210 44 19 3 7 1772 852IBL 055-4-1 times Souna 3 0 58 241 38 27 3 8 2232 1397IBL 091-1-1 times Souna 3 0 54 250 54 20 4 8 2369 1211IBL 095-4-1 times Souna 3 0 52 262 58 20 4 9 2975 1641IBL 098-3-1 times Souna 3 19 54 277 46 19 4 9 2326 1289IBL 106-B-1 times Souna 3 6 56 256 52 16 3 9 2462 1351IBL 110-B-1 times Souna 3 0 56 274 52 26 5 7 4190 1493IBL 114-6-1 times Souna 3 4 57 270 47 20 3 8 2991 1181IBL 119-B-1 times Souna 3 0 56 321 49 20 5 9 3586 1530IBL 155-2-1 times Souna 3 22 56 287 46 19 5 9 2562 1101IBL 165-1-1 times Souna 3 0 59 289 45 21 4 8 3420 1612IBL 179-2-1 times Souna 3 0 59 298 44 20 3 9 1906 735IBL 179-3-1 times Souna 3 2 55 275 46 22 4 8 2943 1402IBL 206-1-1 times Souna 3 2 54 245 44 21 5 9 3671 2024IBL 001-4-1 times Sosat C 88 9 56 284 36 24 4 9 2997 1579IBL 003-B-1 times Sosat C 88 2 50 234 28 26 4 12 3182 1883IBL 011-4-1 times Sosat C 88 0 50 257 39 21 5 10 2468 1331IBL 021-3-1 times Sosat C 88 0 54 284 37 23 4 10 3053 1654IBL 055-4-1 times Sosat C 88 0 57 298 40 20 3 9 1824 1131IBL 091-1-1 times Sosat C 88 0 50 260 41 23 4 10 2912 2019IBL 095-4-1 times Sosat C 88 2 55 281 39 23 4 10 2426 1368IBL 098-3-1 times Sosat C 88 6 57 285 43 22 3 9 2722 1381IBL 106-B-1 times Sosat C 88 0 57 255 37 22 3 9 1933 949IBL 110-B-1 times Sosat C 88 2 55 256 38 26 4 9 2827 1433IBL 114-6-1 times Sosat C 88 0 52 264 31 24 5 9 2944 1416IBL 119-B-1 times Sosat C 88 2 60 298 41 20 4 8 1993 871IBL 155-2-1 times Sosat C 88 0 51 260 35 19 6 10 2414 1215IBL 165-1-1 times Sosat C 88 0 60 287 39 25 4 10 2785 1114IBL 179-2-1 times Sosat C 88 0 54 277 32 24 6 9 2920 1586IBL 179-3-1 times Sosat C 88 0 56 260 29 24 4 9 2375 1247IBL 206-1-1 times Sosat C 8 0 53 242 34 24 5 9 3325 1988Souna 3 5 56 273 55 20 4 8 2918 1268


Table 3 Continued

Genotype DMI FWT PHIG PLEN PDIA PT TGW PY GYSosat C 88 2 51 251 33 23 4 10 2568 1548Thialack II 7 53 292 54 19 4 8 3380 1694Mean 4 56 259 41 21 4 9 2313 1171Range 0ndash22 50ndash69 200ndash321 27ndash58 12ndash27 2ndash6 5ndash12 376ndash4190 92ndash2024Standard deviation 56 41 258 73 03 09 14 8688 4831DMI downymildew incidence FWT flowering PH plant height PL panicle length PDIA panicle diameter PT productive tillers TGW 1000-grain weightPY panicle yield GY grain yield

genotypes across sites were hybrids IBL 206-1-1 times Souna 3(2024 kg haminus1) IBL 091-1-1 times Sosat C 88 (2019 kg haminus1) IBL206-1-1 times Sosat C 88 (1988 kg haminus1) IBL 001-4-1 times Souna 3(1923 kg haminus1) and IBL 003-B-1 times Sosat C 88 (1883 kg haminus1)Among these top hybrids two involved the inbred lineIBL 206-1-1 as parent The hybrid IBL 179-2-1 times Souna3 (735 kg haminus1) was the lowest yielding among the testedhybridsThe checkThialack II was themost productiveOPVwith an average grain yield of 1694 kg haminus1 and ranked amongthe ten best genotypes The best inbred line was IBL 003-B-1(1340 kg haminus1)

Genotypes flowered 2 days earlier in Nioro (55 DAS)compared to Bambey (57 DAS) (Table 4) The average TWGin Nioro was 8 g while in Bambey it was 9 g The panicleyield of genotypes under Nioro conditions ranged from461 kg haminus1 for the inbred line IBL 110-B-1 to 4647 kg haminus1 forhybrid IBL 110-B-1 times Souna 3 while under Bambey conditionsit varied from 251 kg haminus1 for the inbred IBL 119-B-1 to4660 kg haminus1 for the hybrid IBL 165-1-1 times Souna 3 Grainyield of genotypes under Bambey environment ranged from61 kg haminus1 for inbred IBL 119-B-1 to 2162 kg haminus1 for hybridIBL 165-1-1 times Souna 3 In Nioro the grain yield varied from87 kg haminus1 for inbred line IBL 110-B-1 to 2966 kg haminus1 for thehybrid IBL 206-1-1 times Sosat C 88

Based on grain yield the ten best genotypes inNiorowereonly hybrids while in Bambey the three OPVs were amongthe top ten genotypes The hybrids IBL 091-1-1 times Sosat C88 and IBL 206-1-1 times Souna 3 performed well under bothlocations and were among the best ten genotypes across thetwo environments

32 Combining Ability Analysis across Locations The totalvariation due to crosses was partitioned into line tester andline times tester interaction (Table 5) The mean squares dueto hybrids were significant for all the traits except for PYand GY Line mean squares across the two locations werealso significant for all the traits except for PDIA while testermean squares were not significant for PT PY and GY Linetimes tester mean squares were significant for most traits exceptPDIA PY and GY The mean squares due to line times site weresignificant for TGW PY and GY whereas the mean squaresdue to tester times site interaction were significant for FWT andDMI However the mean squares due to site times line times testerinteractionwere not significant for all the traits across the twolocations

0102030405060708090

100

DMI FWT PH PLEN PDIA PT TGW PY GY

co

ntrib

utio

n of

GCA

m G

CAf

and

SCA

Studied traits

SCAGCAmGCAf

Figure 1 Proportion of total mean squares of studied traitsattributable to GCAm GCAf and SCA across locations DMIdowny mildew incidence FWT flowering time PH plant heightPL panicle length PDIA panicle diameter PT productive tillersTGW 1000-grain weight PY panicle yield GY grain yield GCAmgeneral combining ability formale parent GCAf general combiningability for female parent SCA specific combining ability

33 Relative Contributions of Mean Squares to Additive andNonadditive Effects Across the two locations the relativeimportance of mean squares for additive effect (GCAm +GCAf ) was higher for all the traits compared to the dom-inance effect (SCA) (Figure 1) GCA effects accounted formost of the variation observed formost of the traits withmorethan 80 of the total genotypic variation among hybridsexcept for PH PT PY and GY The overall contribution ofGCA sums of squares to the total mean squares across thetwo locations varied from 58 for GY to 99 for PLENwhileSCA varied from 1 for PLEN to 42 for grain yield Thecontribution of GCAm was higher than GCAf and SCA forDMI PLEN PDIA and TGW while GCAf was larger thanGCAm and SCA mean square for FWT PH PT PY andGYThe contribution of GCAf (50) was slightly higher thanSCA (42) to grain yield

34 Estimation of General Combining Ability Effects Thecontribution of lines and testers to crosses for traits studiedacross the two locations is presented in Table 6 For femalelines significant GCA effects were observed for most of


Table 4 Mean flowering time yield and related traits of genotypes per site

Genotype FWT (das) TGW (g) PY (kg haminus1) GY (kg haminus1)Bambey Nioro Bambey Nioro Bambey Nioro Bambey Nioro

IBL 001-4-1 60 61 9 10 1284 924 768 402IBL 003-B-1 51 52 11 12 1856 1888 1512 1168IBL 011-4-1 63 55 7 7 1195 1132 437 419IBL 021-3-1 62 63 9 7 1423 933 718 119IBL 055-4-1 68 63 5 7 321 712 139 432IBL 091-1-1 63 56 8 8 2557 2099 1140 1132IBL 095-4-1 49 50 10 11 1658 2372 924 969IBL 098-3-1 49 53 9 11 1687 2206 1057 1318IBL 106-B-1 55 54 10 10 780 1900 428 992IBL 110-B-1 61 62 7 5 1533 461 721 87IBL 114-6-1 65 58 6 9 628 873 267 382IBL 119-B-1 73 64 3 6 251 500 61 122IBL 155-2-1 55 58 7 6 1235 962 649 284IBL 165-1-1 64 63 7 8 1970 727 792 186IBL 179-2-1 59 60 8 7 1078 622 559 228IBL 179-3-1 54 53 8 8 1330 1664 746 1025IBL 206-1-1 60 52 8 8 920 3283 564 1687IBL 001-4-1 times Souna 3 54 51 10 12 2625 4325 1223 2624IBL 003-B-1 times Souna 3 52 51 9 10 2758 3677 1011 2281IBL 011-4-1 times Souna 3 54 50 9 8 2151 2585 923 961IBL 021-3-1 times Souna 3 58 56 7 7 1672 1872 1113 591IBL 055-4-1 times Souna 3 59 57 9 8 2140 2324 1609 1185IBL 091-1-1 times Souna 3 55 53 8 7 2375 2363 1295 1127IBL 095-4-1 times Souna 3 53 50 9 8 2847 3102 1513 1768IBL 098-3-1 times Souna 3 56 53 7 10 1983 2669 1018 1559IBL 106-B-1 times Souna 3 57 55 8 9 1908 3015 1005 1697IBL 110-B-1 times Souna 3 59 53 7 7 3733 4647 934 2051IBL 114-6-1 times Souna 3 57 56 7 10 3154 2828 1436 926IBL 119-B-1 times Souna 3 59 53 10 8 4175 2996 1829 1231IBL 155-2-1 times Souna 3 59 54 8 9 1913 3211 907 1294IBL 165-1-1 times Souna 3 60 57 8 8 4660 2180 2162 1061IBL 179-2-1 times Souna 3 60 58 9 8 1728 2084 617 854IBL 179-3-1 times Souna 3 56 54 7 9 2031 3855 822 1982IBL 206-1-1 times Souna 3 56 53 8 11 3285 4058 1609 2438IBL 001-4-1 times Sosat C 88 57 54 9 10 2503 3490 1298 1860IBL 003-B-1 times Sosat C 88 48 51 12 12 3562 2802 1959 1806IBL 011-4-1 times Sosat C 88 49 51 10 10 2380 2555 1259 1403IBL 021-3-1 times Sosat C 88 53 55 9 10 2526 3580 1304 2005IBL 055-4-1 times Sosat C 88 58 56 9 9 1630 2017 1007 1255IBL 091-1-1 times Sosat C 88 48 51 11 10 2563 3262 1976 2061IBL 095-4-1 times Sosat C 88 56 53 9 10 1963 2889 1080 1657IBL 098-3-1 times Sosat C 88 59 55 8 11 1260 4184 404 2357IBL 106-B-1 times Sosat C 88 59 54 8 11 2133 1733 944 953IBL 110-B-1 times Sosat C 88 56 53 9 10 2367 3288 1032 1835IBL 114-6-1 times Sosat C 88 53 51 9 10 2917 2971 1662 1171IBL 119-B-1 times Sosat C 88 59 60 9 7 2992 994 1261 482IBL 155-2-1 times Sosat C 88 51 51 9 11 1939 2889 801 1630IBL 165-1-1 times Sosat C 88 60 59 11 9 3801 1770 1450 778IBL 179-2-1 times Sosat C 88 53 55 9 10 2449 3390 1103 2070IBL 179-3-1 times Sosat C 88 58 54 9 10 1644 3107 727 1767


Table 4 Continued


IBL 206-1-1 times Sosat C 88 54 52 8 9 2411 4240 1010 2966Souna 3 55 56 8 8 3465 2372 1731 805Sosat C 88 50 52 9 10 2956 2180 1707 1389Thialack II 54 52 7 8 3716 3044 1659 1729Mean 57 55 8 9 2186 2441 1072 1270SD 5 4 2 2 955 1089 476 703FWT flowering time TGW 1000-grain weight PY panicle yield GY grain yield

Table 5 Mean squares for combining ability for studied traits across locations

Source of variation df DMI FWT PH PLEN PDIA PT TGW PY GYRep (site) 2 555 127 3009 12 07 31 50 316965 25012Site 1 1588lowast 1788lowastlowastlowast 7116 2800lowastlowast 02 122lowast 261lowastlowast 9629606lowastlowast 6762757lowastlowastlowast

Hybrid 33 1881lowastlowastlowast 457lowastlowastlowast 28524lowastlowastlowast 3094lowastlowastlowast 05lowast 43lowastlowast 62lowastlowastlowast 1962646 688597Line (GCA) 16 2296lowastlowastlowast 649lowastlowastlowast 36078lowastlowastlowast 1606lowastlowastlowast 04 54lowastlowast 44lowastlowast 2290926lowast 775061lowast

Tester (GCA) 1 7765lowastlowastlowast 405lowastlowast 2707 62261lowastlowastlowast 16lowast 07 648lowastlowastlowast 1998612 123285Line times tester (SCA) 16 1100lowastlowast 268lowastlowastlowast 22586lowastlowastlowast 885lowastlowastlowast 04 34lowast 44lowastlowastlowast 1632117 637466Site times line 16 524 75 3114 180 03 23 39lowastlowast 3292948lowastlowast 1351732lowastlowastlowast

Site times tester 1 1844lowast 540lowastlowast 791 261 16 09 004 95074 444360Site times line times tester 16 641 60 1739 282 03 12 12 703213 424419Error 134 397 53 2817 254 03 19 18 1244846 414329DMI downy mildew incidence FWT flowering time PH plant height PL panicle length PDIA panicle diameter PT productive tillers TGW 1000-grain weight PY panicle yield GY grain yield GCA general combining ability SCA specific combining ability df degree of freedom Rep replicationlowastlowastlowastlowastlowastlowastSignificant at 005 and 001 and 0001 probability levels respectively

Table 6 Estimates of GCA effects of lines and testers evaluated across the two sites

Lines DMI () FWT (das) PH (cm) PLEN (cm) PDIA (cm) PT TGW (g) PY (kg haminus1) GY (kg haminus1)IBL 001-4-1 97lowastlowastlowast minus08 101 minus25 01 06 11 4839 3544IBL 003-B-1 16 minus42lowastlowastlowast minus217lowastlowastlowast minus57lowastlowastlowast 03 02 17lowast 4479 3674IBL 011-4-1 minus04 minus38lowastlowastlowast minus120lowast 30lowast minus03 03 00 minus3341 minus2604IBL 021-3-1 minus11 08 minus213lowastlowastlowast minus12 minus02 minus08 minus05 minus3391 minus1438IBL 055-4-1 minus32 26lowastlowast 09 minus29lowast 03 minus12lowastlowast minus04 minus7242 minus1329IBL 091-1-1 minus32 minus30lowastlowast minus132lowast 55lowastlowastlowast minus01 minus02 00 minus1112 2179IBL 095-4-1 minus24 minus17lowast 30 67lowastlowastlowast minus02 minus02 00 minus517 1075IBL 098-3-1 90lowastlowastlowast 08 125lowast 28lowast 00 minus06 minus01 minus2279 minus622IBL 106-B-1 minus04 14 minus125lowast 23 minus02 minus11lowast 01 minus5546 minus2470IBL 110-B-1 minus23 06 minus34 30lowast 04 04 minus09 7567 662IBL 114-6-1 minus14 minus05 minus17 minus27lowast 00 minus02 minus03 2157 minus982IBL 119-B-1 minus24 29lowastlowast 412lowastlowastlowast 33lowast minus02 03 minus04 374 minus1964IBL 155-2-1 76lowastlowast minus10 53 minus12 minus02 13lowastlowast 02 minus2639 minus2390IBL 165-1-1 minus32 42lowastlowastlowast 198lowastlowastlowast 03 02 00 minus01 3507 minus342IBL 179-2-1 minus32 16 194lowastlowastlowast minus37lowastlowast 00 03 minus01 minus3391 minus2360IBL 179-3-1 minus24 09 minus11 minus43lowastlowast 01 minus02 minus03 minus929 minus724IBL 206-1-1 minus23 minus09 minus252lowastlowastlowast minus27lowast 00 09lowast 00 7465 6090SE 20 08 49 12 02 04 06 5082 3256TestersSouna 3 20 04 minus12 55 minus01 minus01 minus06lowast 990 minus246Sosat C 88 minus20 minus04 12 minus55 01 01 06lowast minus990 246SE 10 05 06 04 01 01 00 216 467DMI downy mildew incidence FWT flowering time PH plant height PL panicle length PDIA panicle diameter PT productive tillers TGW 1000-grainweight PY panicle yield GY grain yield lowastlowastlowastlowastlowastlowastSignificant at 005 and 001 and 0001 probability levels respectively


the traits while for male lines significant GCA effects wererecorded only for TGW For DMI the GCA effects variedfrom minus32 for IBL 091-1-1 to 97 for IBL 001-4-1 Positive andsignificant GCA effects for DMI were observed on parentallines IBL 001-4-1 IBL 098-3-1 and IBL 155-2-1 For FWTGCA effects ranged from minus42 for IBL 003-B-1 to 42 forIBL 165-1-1 and both positive and negative significant GCAeffectswere observed Estimates ofGCAeffects for PH rangedfrom minus252 for IBL 206-1-1 to 194 for IBL 179-2-1 Out ofthe 19 parental lines six showed negative and significanteffects whereas four lines exhibited positive and significanteffects for PH GCA effects for PLEN varied from minus57 forIBL 003-B-1 to 67 for IBL 095-4-1 with both positive andnegative significant effects whereas GCA effects for PDIAranged from minus03 for IBL 011-4-1 to 04 for IBL 110-B-1 withno significant effects The GCA effects due to parental linesfor PT across locations varied from minus12 to 13 for IBL 055-4-1 and IBL 155-2-1 respectively Significant positive GCAeffects for PT were observed in lines IBL 155-2-1 and IBL 206-1-1 while significant negative GCA effects were observed inlines IBL 055-4-1 and IBL 106-B-1 Across research stationsthe GCA for TGW ranged from minus09 for IBL 110-B-1 to 17for IBL 003-B-1 The tester Sosat C 88 and the inbred lineIBL 003-B-1 had significant positive GCA effects while thetester Souna 3 showed significant negative GCA effects forTGW For PY and GY traits no significant GCA effects wereshowedHowever amongparental lines inbred lines IBL 206-1-1 IBL 003-B-1 IBL 001-4-1 IBL 091-1-1 IBL 095-4-1 andIBL 110-B-1 manifested desirable positive GCA effects for GYand most other studied traits for the two research stationsIn contrast inbred lines IBL 011-4-1 IBL 106-B-1 IBL 155-2-1 and IBL 179-2-1 ranked among the worst lines for GY withnegative GCA effects

35 Estimation of Specific Combining Ability Effects Signifi-cant positive and negative SCA effects were recorded for allthe observed traits (Table 7) The top-cross hybrid IBL 155-2-1 times Sosat C 88 was the only one which exhibited negativeand significant SCA effects for DMI In addition its SCAeffects for FWT and PH were negative and significant whileits SCA effects for PT were significant and positive Among34 top-cross hybrids six top-cross hybrids had significantSCA effects of which three were positive All the significantand positive SCA effects for PY and GY were recorded in thecrosses among Sosat C 88 with the inbred lines IBL 179-2-1IBL 091-1-1 and IBL 021-3-1

36 Estimation of Standard Best and Mid-Parent Heterosisfor Grain Yield across Locations The estimates of best par-ent mid-parent and standard heterosis for grain yield aresummarized in Table 8 The best parent heterosis for grainyield across the two locations varied from minus44 to 60 and 17hybrids displayed positive best parent heterosis IBL 206-1-1times Souna 3 followed by IBL 001-4-1 times Souna 3 had the largestbest parent heterosis for grain yield and was among the bestfive hybrids while IBL 119-B-1 times Sosat C 88 had the least bestparent heterosis value The mid-parent heterosis varied fromminus16 for IBL 106-B-1 times Sosat C 88 to 125 for IBL 119-B-1times Souna 3 which was not among the ten best hybrids All the

crosses displayed positivemid-parent heterosis for grain yieldexcept IBL 106-B-1 times Sosat C 88 (minus16) and IBL 179-2-1 timesSouna 3 (minus12)The standard heterosis values for grain yieldacross the experimental sites varied from minus57 for IBL 179-2-1 times Souna 3 to 20 for IBL 206-1-1 times Souna 3 The crossesIBL 206-1-1 times Souna 3 IBL 091-1-1 times Sosat C 88 IBL 206-1-1 timesSosat C 88 IBL 001-4-1 times Souna 3 and IBL 003-B-1 times Sosat C88 exhibited positive standard heterosis for grain yieldThesehybrids were the top best five and displayed also both positivebetter and mid-parent heterosis values for grain yield

4 Discussion

The significant differences observed among the genotypesfor all the characters studied indicated the presence of largeamount of genetic variability among the inbred lines theOPVs and their crosses which is a prerequisite in theestablishment of a successful breeding programme Geneticvariability for downy mildew disease and several agronomictraits has been also reported in many studies conducted inWest and Central Africa [14 16ndash19]The results indicated alsothe influence of the environment on the performance of thegenotypes for FWT TGW PY andGY traits as their genotypetimes location interaction effect was significantThe environmenteffect in the performance of genotypes for flowering timewas also reported in Burkina Faso [14] The mean grain yieldat Nioro research station was higher compared to Bambeyresearch station This could be explained by rainfall patternand soil texture variability existing between the two locationswhere the experiments were established Bambey researchstation is located in the northern part of the groundnut basinin the Sudano-Sahelian area and the soil texture is sandywhileNioro research station located in the southern part of thegroundnut basin in the Sudanese zone has sandy-clay soiltexture However despite the site effect on grain yield andyield related traits some of the genotypes such as IBL 091-1-1 IBL 091-1-1 times Sosat C 88 and Thialack II have performedwell under the two environments

Besides the existence of useful variability the establish-ment of a successful breeding programme depends on adeep understanding of the underlying gene action of thetraits of interest Indeed this genetic information will guidebreeders on which breeding methods and lines to use forthe development of improved varieties [9] In this studyGCA and SCA mean squares were significant for all thetraits studied except for the SCA of PDIA PY and GY traitsindicating that both additive and nonadditive gene actionswere important for the inheritance of these traits across thetwo locationsThis result is contrary to the findings of [16 17]that reported only significant GCA effects for agronomictraits such as flowering time downy mildew incidence plantheight and panicle length However in the present studythe larger proportion of GCA over SCA mean squares formost of the traits such as DMI FWT PL PDIA and TGWindicated the preponderance of additive gene action overnonadditive gene action This would imply that recurrentselection could be effectively used for improvement of thesetraits The result of this study is consistent with that of [14]that reported additive gene action to be more important that


Table 7 Estimates of SCA effects for hybrids evaluated across the two sites

Hybrid DMI () FWT (das) PH (cm) PLEN (cm) PDIA (cm) PT TGW (g) PY (kg haminus1) GY (kg haminus1)IBL 001-4-1 times Souna 3 25 minus19lowast minus47 minus18 0 06 12lowastlowastlowast 1403 1968IBL 003-B-1 times Souna 3 11 05 138lowastlowastlowast 26 minus03lowastlowast 02 minus09lowastlowast minus811 minus936IBL 011-4-1 times Souna 3 08 07 02 02 minus01 minus01 minus01 minus1488 minus1701IBL 021-3-1 times Souna 3 01 1 minus354lowastlowastlowast minus23 minus01 minus04 minus08lowast minus7397lowastlowast minus3765lowastIBL 055-4-1 times Souna 3 minus2 02 minus272lowastlowastlowast minus6lowastlowastlowast 05lowastlowastlowast 04 01 1052 1576IBL 091-1-1 times Souna 3 minus2 18lowast minus37 09 0 minus04 minus09lowastlowast minus3706lowast minus3793lowastIBL 095-4-1 times Souna 3 minus28 minus2lowastlowast minus83lowast 42lowastlowast 01 04 01 1754 1608IBL 098-3-1 times Souna 3 44 minus17lowast minus29 minus4lowast minus01 05 03 minus2966 minus215IBL 106-B-1 times Souna 3 09 minus08 14 21 minus01 minus02 01 1656 226IBL 110-B-1 times Souna 3 minus29 03 103lowastlowast 19 02 06 minus05 5823lowast 542IBL 114-6-1 times Souna 3 minus02 18lowast 42 22 minus01 minus06 0 minus756 minus929IBL 119-B-1 times Souna 3 minus28 minus23lowastlowast 124lowastlowast minus1 01 04 09lowastlowast 6974lowastlowast 3541IBL 155-2-1 times Souna 3 88lowastlowastlowast 21lowastlowast 145lowastlowastlowast 03 01 minus08lowast 0 minus25 minus328IBL 165-1-1 times Souna 3 minus2 minus09 23 minus26 minus02 04 minus05 2184 2735IBL 179-2-1 times Souna 3 minus2 21lowastlowast 118lowastlowast 05 01 minus12lowastlowastlowast 03 minus6057lowast minus4008lowastIBL 179-3-1 times Souna 3 minus11 minus09 85lowast 32lowast minus02 03 0 1849 1023IBL 206-1-1 times Souna 3 minus1 01 27 minus04 01 minus02 07lowast 739 423IBL 001-4-1 times Sosat C 88 minus25 19lowast 47 18 0 minus06 minus12lowastlowastlowast minus1403 minus1968IBL 003-B-1 times Sosat C 88 minus11 minus05 minus138lowastlowastlowast minus26 03lowastlowast minus02 09lowastlowastlowast 811 936IBL 011-4-1 times Sosat C 88 minus08 minus07 minus02 minus02 01 01 01 1488 1701IBL 021-3-1 times Sosat C 88 minus01 minus1 354lowastlowastlowast 23 01 04 08lowast 7397lowastlowast 3765lowast

IBL 055-4-1 times Sosat C 88 2 minus02 272lowastlowastlowast 6lowastlowastlowast minus05lowastlowastlowast minus04 minus01 minus1052 minus1576IBL 091-1-1 times Sosat C 88 2 minus18lowast 37 minus09 0 04 09lowastlowast 3706lowast 3793lowast

IBL 095-4-1 times Sosat C 88 28 2lowastlowast 83lowast minus42lowastlowast minus01 minus04 minus01 minus1754 minus1608IBL 098-3-1 times Sosat C 88 minus44 17lowast 29 4lowast 01 minus05 minus03 2966 215IBL 106-B-1 times Sosat C 88 minus09 08 minus14 minus21 01 02 minus01 minus1656 minus226IBL 110-B-1 times Sosat C 88 29 minus03 minus103lowastlowast minus19 minus02 minus06 05 minus5823lowast minus542IBL 114-6-1 times Sosat C 88 02 minus18lowast minus42 minus22 01 06 0 756 929IBL 119-B-1 times Sosat C 88 28 23lowastlowast minus124lowastlowast 1 minus01 minus04 minus09lowastlowast minus6974lowastlowast minus3541IBL 155-2-1 times Sosat C 88 minus88lowastlowastlowast minus21lowastlowast minus145lowastlowastlowast minus03 minus01 08lowast 0 25 328IBL 165-1-1 times Sosat C 88 2 09 minus23 26 02 minus04 05 minus2184 minus2735IBL 179-2-1 times Sosat C 88 2 minus21lowastlowast minus118lowastlowast minus05 minus01 12lowastlowastlowast minus03 6057lowast 4008lowast

IBL 179-3-1 times Sosat C 88 11 09 minus85lowast minus32lowast 02 minus03 0 minus1849 minus1023IBL 206-1-1 times Sosat C 8 1 minus01 minus27 04 minus01 02 minus07lowast minus739 minus423SE 22 07 37 15 01 03 03 2348 1825DMI downy mildew incidence FWT flowering time PH plant height PL panicle length PDIA panicle diameter PT productive tillers TGW 1000-grainweight PY panicle yield GY grain yield lowastlowastlowastlowastlowastlowastSignificant at 005 and 001 and 0001 probability levels respectively

nonadditive gene action in controlling agronomic traits suchas grain yield flowering time and panicle length Similarly[20] reported the importance of additive gene action overnonadditive gene action in the expression of panicle lengthand diameter The additive gene action was also reportedfor other traits in pearl millet such as Fe and Zn densities[11] For grain yield the significance of GCAf and the lackof significance for SCA suggest that grain yield is controlledby additive gene effects as reported by several authors [1416] However the slight difference of their mean squaressuggests that nonadditive gene action is also important inthe inheritance of grain yield trait This study has alsoprovided information on parental effects in controlling thetraits studied The larger GCAm mean squares over GCAf

mean squares for DMI PL PDIA and TGW display the roleof paternal effects in the control of these traits while the largerGCAf mean squares over GCAmmean squares for FWT PHPT and GY suggest the role of maternal effects in the controlof these traits across the two locations Similarly [14] found apaternal effect in controlling PDIA and a maternal effect forFWT and PH under different locations in Burkina Faso Thebest performing cross for high grain yield and resistance todownymildew disease may be produced by crossing themaleparents resistant to the disease with female parents havinggood yield potential

Inbred lines IBL 001-4-1 IBL 003-B-1 IBL 091-1-1 IBL095-4-1 IBL 110-B-1 and IBL 206-1-1 had positive GCAeffects for grain yield indicating that these lines contributed


Table 8 Mean grain yield and best and mid-parent heterosis of pearl millet hybrid across locations

Cross GY (kg haminus1) BPH MPH SHIBL 001-4-1 times Souna 3 1923 52 108 14IBL 003-B-1 times Souna 3 1646 23 26 minus3IBL 011-4-1 times Souna 3 942 minus26 11 minus44IBL 021-3-1 times Souna 3 852 minus33 1 minus50IBL 055-4-1 times Souna 3 1397 10 80 minus18IBL 091-1-1 times Souna 3 1211 minus4 1 minus29IBL 095-4-1 times Souna 3 1641 29 48 minus3IBL 098-3-1 times Souna 3 1289 2 5 minus24IBL 106-B-1 times Souna 3 1351 7 37 minus20IBL 110-B-1 times Souna 3 1493 18 79 minus12IBL 114-6-1 times Souna 3 1181 minus7 48 minus30IBL 119-B-1 times Souna 3 1530 21 125 minus10IBL 155-2-1 times Souna 3 1101 minus13 27 minus35IBL 165-1-1 times Souna 3 1612 27 83 minus5IBL 179-2-1 times Souna 3 735 minus42 minus12 minus57IBL 179-3-1 times Souna 3 1402 11 30 minus17IBL 206-1-1 times Souna 3 2024 60 69 20IBL 001-4-1 times Sosat C 88 1579 2 48 minus7IBL 003-B-1 times Sosat C 88 1883 22 30 11IBL 011-4-1 times Sosat C 88 1331 minus14 35 minus21IBL 021-3-1 times Sosat C 88 1654 7 68 minus2IBL 055-4-1 times Sosat C 88 1131 minus27 23 minus33IBL 091-1-1 times Sosat C 88 2019 30 50 19IBL 095-4-1 times Sosat C 88 1368 minus12 10 minus19IBL 098-3-1 times Sosat C 88 1381 minus11 1 minus18IBL 106-B-1 times Sosat C 88 949 minus39 minus16 minus44IBL 110-B-1 times Sosat C 88 1433 minus7 47 minus15IBL 114-6-1 times Sosat C 88 1416 minus9 51 minus16IBL 119-B-1 times Sosat C 88 871 minus44 6 minus49IBL 155-2-1 times Sosat C 88 1215 minus22 21 minus28IBL 165-1-1 times Sosat C 88 1114 minus28 9 minus34IBL 179-2-1 times Sosat C 88 1586 2 63 minus6IBL 179-3-1 times Sosat C 88 1247 minus19 2 minus26IBL 206-1-1 times Sosat C 8 1988 28 49 17GY grain yield BPH best parent heterosis MPH mid-parent heterosis SH standard heterosis

favorable alleles for grain yield They produced hybrids thatwere among the best 15 across the two locations Thussuch lines could be used as parents to create high yieldingsynthetic or 1198651 hybrid varieties However IBL 001-4-1 unlikethe other five inbred lines had positive and significant GCAeffect for downymildew and produced hybrids with a certainlevel of disease incidence The other lines showed negativeGCA effects and would be good sources of resistance fordowny mildew under Senegalese growing conditions Inaddition they had negative GCA effects for flowering timeand plant height Thus their cross is expected to producea medium plant height and early maturing synthetic pearlmillet varieties tolerant to the downy mildew disease withimproved grain yield

In this study the top-cross hybrids performed betterthan the inbred lines and OPVs The top five genotypes

across the two locations were hybrids showing evidenceof heterosis for grain yield in pearl millet which has beenalso reported previously [5 14 16] Grain yield showed amid-parent heterosis ranging from minus16 to 125 and mostof the hybrids except IBL 106-B-1 times Sosat C 88 and IBL179-2-1 times Souna 3 exceeded the parental lines This findingis consistent with [18] that reported mid-parent heterosisranging from 19 to 98 for top-crosses evaluated under lowP conditions Information about the performance of hybridscompared to the standard check is needed for the farmerto determine the benefit of growing hybrid In this studya maximum standard heterosis of 20 for grain yield wasobserved providing advantage of growing hybrids comparedto the local cultivars Similar standard heterosis for grain yieldwas also reported in Burkina Faso [14] The higher meanperformance of the crosses compared to their parents and the


control check indicate great potential for hybrid pearl milletbreeding Therefore this technology can be a good strategyto increase pearl millet production like in India where morethan 70 of the pearl millet cultivated area is sown with 1198651hybrids [5] However a strong hybrid pearl millet breedingprogramme needs to be established

5 Conclusion

The present study revealed that the crosses IBL 206-1-1 timesSouna 3 IBL 091-1-1 times Sosat C 88 IBL 206-1-1 times Sosat C 88IBL 001-4-1 times Souna 3 and IBL 003-B-1 times Sosat C 88 werethe top five hybrids and exhibited positive best parent mid-parent and standard heterosis for grain yield Furthermoreboth additive and nonadditive gene action were involved inthe inheritance of almost all the traits studied However thecontribution of the additive gene action was higher than thatof nonadditive gene action for all the traits Inbred lines IBL003-B-1 IBL 091-1-1 IBL 095-4-1 IBL 110-B-1 and IBL 206-1-1 exhibited positive GCA effects for grain yield and negativeGCA effects for flowering time downy mildew disease andplant height These lines can be used as parents for breedinghigh yielding synthetic varieties or hybrids1198651 adapted toWestand Central African countries

Conflicts of Interest

The authors declare no conflicts of interest regarding thepublication of this paper

Acknowledgments

The authors are thankful to the West Africa AgriculturalProductivity Program (WAAPP) This work could not havebeen done without the funding received from the WAAPP

References

[1] FAO FAO Database for agriculture statistics 2015 httpfaostatfaoorg

[2] V Rajaram T Nepolean S Senthilvel et al ldquoPearl millet[Pennisetum glaucum (L) R Br] consensus linkage map con-structed using four RIL mapping populations and newly devel-oped EST-SSRsrdquo BMC Genomics vol 14 no 1 pp 1ndash15 2013

[3] V S Nambiar J J Dhaduk N Sareen T Shahu and R DesaildquoPotential functional implications of pearl millet (Pennisetumglaucum) in health and diseaserdquo Journal of Applied Pharmaceu-tical Science vol 1 no 10 pp 62ndash67 2011

[4] Y Camara M C S Bantilan and J Ndjeunga Impacts ofSorghumandMillet Research inWest AndCentral Africa (WCA)A Synthesis and Lessons Learnt International Crops ResearchInstitute for the Semi-Arid Tropics 2006

[5] O P Yadav and K N Rai ldquoGenetic Improvement of PearlMilletin Indiardquo Agricultural Research vol 2 no 4 pp 275ndash292 2013

[6] S L Tan ldquoCassava silently the tuber fills the lowly cassavaregarded as a poor mans crop may help save the Euphyticaworld from the curse of plastic pollutionrdquo Utar AgricultureScience Journal vol 1 pp 12ndash24 2015

[7] B A Christinck M Diarra and G Horneber Innovations inSeed Systems Lessons from the CCRP Funded Project Sustainingfarmer-managed Seed Initiatives in Mali Niger and BurkinaFaso International Crops Research Institute for the Semi-AridTropics 2014

[8] A R Hallauer M J Carena and J B Miranda-FilhoQuantita-tive Genetics in Maize Breeding Springer New York NY USA2010

[9] D S Falconer and T F C Mackay Introduction to QuantitativeGenetics Longman New York NY USA 1996

[10] O KempthorneAn introduction to genetic statistics JohnWileyand Sons Inc New York NY USA and London UK 1957

[11] M Govindaraj K N Rai P Shanmugasundaram et al ldquoCom-bining ability and heterosis for grain iron and zinc densities inpearl milletrdquo Crop Science vol 53 no 2 pp 507ndash517 2013

[12] R S Parmar G S Vala V N Gohil and A S Dudhat ldquoStudieson combining ability for development of new hybrids in pearlmillet [Pennisetum gaucum (L) R BR]rdquo International Journalof Plant Science vol 8 no 2 pp 405ndash409 2013

[13] V P Chaudhary K K Dhedhi H J Joshi and D R MehtaldquoCombining ability studies in line x tester crosses of pearl millet[Pennisetum glaucum (L) R Br]rdquo Research on Crops vol 13no 3 pp 1094ndash1097 2012

[14] I Drabo Breeding pearl millet (Pennisetum glaucum (L) R BR)for downy mildew resistance and improved yield in Burkina Faso[PhD thesis] University of Ghana 2016

[15] D C Gemenet W L Leiser R G Zangre et al ldquoAssociationanalysis of low-phosphorus tolerance in West African pearlmillet using DArT markersrdquo Molecular Breeding vol 35 no 8pp 1ndash20 2015

[16] B Ouendeba G Ejeta W E Nyquist W W Hanna and AKumar ldquoHeterosis and Combining Ability among African PearlMillet LandracesrdquoCrop Science vol 33 no 4 pp 735ndash739 1993

[17] A Issaka Development of Downy Mildew Resistant F1 pearlmillet Hybrids in Niger [PhD thesis] University of Ghana 2012

[18] D C Gemenet C T Tom O Sy et al ldquoPearl millet inbred andtestcross performance under low phosphorus in West AfricardquoCrop Science vol 54 no 6 pp 2574ndash2585 2014

[19] A Pucher O Sy M D Sanogo et al ldquoCombining ability pat-terns among West African pearl millet landraces and prospectsfor pearl millet hybrid breedingrdquo Field Crops Research vol 195pp 9ndash20 2016

[20] A S Jethva L Raval R B Madriya D R Mehta and C Man-davia ldquoCombing ability over environments for grain yield andits related traits in pearl milletrdquo Crop Improvement vol 38 no1 pp 92ndash96 2011

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particularly hybrids since the 1960s Indeed in India hybridshad 25ndash30 grain yield advantage over OPVs leading tothe rapid adoption of the hybrids whose yield increasedfrom 305 kg haminus1 during 1951ndash1955 to 998 kg haminus1 during2008ndash2012 [5] Thus enhancement of pearl millet produc-tion and productivity in Africa which is a high prioritycan be achieved through the identification of elite parentmaterials which can be used as parents to develop hybridvarieties

ICRISAT has developed pearl millet inbred lines derivedfrom landraces originating from West and Central Africawhich can be useful in developing high yielding pearl millethybrids and synthetic varieties with considerable adaptationto this pearl millet growing environment These lines werescreened for pearl millet downy mildew resistance in Senegaland some of them showed good agronomic traits and resis-tance to the pearl millet downy mildew However the perse performance of these pearl millet inbred lines does notpredict the performance of hybrids for disease resistance andagronomic traits [8]Therefore to make effective use of thesepearl millet inbred lines their combining abilities need tobe elucidated [9] This genetic information can be obtainedby different mating design including line times tester [10] GCAand SCA estimates of pearl millet inbred parents or landracesfor different traits such as micronutrients [11] grain quality[12] and fodder yield [13] were reported to be importantAdditive genetic action was also reported to be importantin controlling traits such as grain yield flowering time andpanicle length [14] There is scanty published informationon the combining ability of the pearl millet inbred linesderived from landraces collected in West and Central Africaknown as the origin of the crop for disease resistance andagronomic traitsThe objectives of this study were to estimatecombining ability and heterosis of pearl millet inbred linesfor downy mildew yield and other agronomic traits underdowny mildew infested fields and identify superior pearlmillet hybrids for yield yield components and resistance todowny mildew

2 Materials and Methods

21 PlantMaterial andMatingDesign Seventeen inbred lineswere used as females and crossed each to two OPVs usedas males according to the line times tester mating design [10] togenerate 34 1198651 hybrids The OPVs varieties were consideredas testers and the inbred lines as lines The two testers namedSouna 3 and Sosat C 88 are popular varieties adapted to thegroundnut agroecological zone The pearl millet inbred linesused for the study were selected from a pool of pearl milletlandraces from West and Central Africa converted to inbredlines through successive selfing up to S6 [15] These inbredlines were selected through a downy mildew phenotypicevaluation conducted at Bambey and Nioro research stationsduring the rainy season 2016 They showed less than 10DMI and were classified as resistant varieties The seeds ofthe male parents were planted in 4 different dates in orderto synchronise the flowering time of these male parents withthe ones of the female parents Thus from January 2017 thesowing of the male parents was done every week and seeds of

each of the male parents were sown in 5 rows of 15 hills perrow All the female parents were sown in one time during thesecond sowing date of the male parents in a one row-plot of15 hills At the booting stage at least plant heads of 4 paniclesper plant of the male and female parents were covered inorder to avoid undesirable pollination At flowering eachcovered panicle of female plant was pollinated with bulkpollen collected from at least 20 different plants of the maleparent

At maturity stage 1198651 panicles of the female parents wereharvested and the lower and upper parts of each panicle werecut before threshing to minimize outcrossing from unknownplants or selfing Indeed because of the protogynous natureof the crop the stigmata of a plant are receptive before theshedding of pollen and the flowering starts from the upperto the lower part Then the upper part of the panicle may bepollinated by unknown plants if not covered on the right timeand the lower part of the panicle may be pollinated by thepollen from the same plant

After threshing 1198651 seeds from the same female parentwere bulked and used as 1198651 hybrids The 34 1198651 hybrids alongwith the 17 inbred lines the two testers and an OPV namedThialack II as check providing 54 genotypes were used forthe evaluation (Table 1)

22 Study Sites Experimental Design and Field ManagementThe 34 hybrids together with their parents and the OPVcheck were evaluated under rainfed conditions during therainy season of 2017 at two locations in Senegal The studysites were Bambey (13∘4910158401210158401015840 North 13∘5510158401210158401015840 West) andNioro (13∘451015840010158401015840 North 15∘481015840010158401015840 West) research stationsBoth locations are in the groundnut agroecological zonethe main pearl millet growing area in Senegal and werecharacterized as hotspots for downy mildew in the previousstudy The genotypes were arranged in 9 times 6 alpha latticedesign with three replications at each site Each block wassurrounded by a downy mildew infector row consisting of adowny mildew susceptible line 7042 S sown 3 weeks beforethe tested materials Each plot consisted of one row of 81mlength with a spacing of 09m between rows and betweenplants within a row At least 10 seeds were planted per holeand later thinned to two plants two weeks after sowing Thefields were weeded two times after sowingThe trials receivedthe recommended 15N-15P-15K basal fertilizer at a rate of150 kg haminus1 just before sowing During the crop developmenta top dressing using area at a rate of 100 kg haminus1 was done intwo fractions 50 kg haminus1 after thinning and 50 kg haminus1 afterthe second weeding

23 Data Collection The recorded data were collectedaccording to the method described by Drabo [14] Flowering(FWT) was recorded by counting the total number of daysfrom sowing to the time when 50 of plants in a plotflowered Downy mildew incidence (DMI) was obtained bydividing the total number of infected plants 30 DAS from aplot by the total number of plants Panicles harvested in aplot were weighed to determine panicle yield (PY) and thenthreshedGrains obtained in each plotwereweighed andused






plot size m2] (1)



119884119894119895119896 = 120583 + 119866119894 + 119871119895 + GL119894119895 + 119903119895119896 + 119887119895119896 + 119890119894119895119896 (2)

where




119884119894119895119896 = 120583 +119872119894 + 119865119895 +MF119894119895 + 119890119894119895119896 (3)

where













(4)

where








(5)

where





MPtimes 100


(6)


3 Results








Table 3 Continued






0102030405060708090

100


co

ntrib

utio

n of

GCA

m G

CAf

and

SCA

Studied traits

SCAGCAmGCAf









Table 4 Continued















4 Discussion




















5 Conclusion




Acknowledgments


References






















Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy









plot size m2] (1)



119884119894119895119896 = 120583 + 119866119894 + 119871119895 + GL119894119895 + 119903119895119896 + 119887119895119896 + 119890119894119895119896 (2)

where




119884119894119895119896 = 120583 +119872119894 + 119865119895 +MF119894119895 + 119890119894119895119896 (3)

where













(4)

where








(5)

where





MPtimes 100


(6)


3 Results








Table 3 Continued






0102030405060708090

100


co

ntrib

utio

n of

GCA

m G

CAf

and

SCA

Studied traits

SCAGCAmGCAf









Table 4 Continued















4 Discussion




















5 Conclusion




Acknowledgments


References






















Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy















(4)

where








(5)

where





MPtimes 100


(6)


3 Results








Table 3 Continued






0102030405060708090

100


co

ntrib

utio

n of

GCA

m G

CAf

and

SCA

Studied traits

SCAGCAmGCAf









Table 4 Continued















4 Discussion




















5 Conclusion




Acknowledgments


References






















Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy








Table 3 Continued






0102030405060708090

100


co

ntrib

utio

n of

GCA

m G

CAf

and

SCA

Studied traits

SCAGCAmGCAf









Table 4 Continued















4 Discussion




















5 Conclusion




Acknowledgments


References






















Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy









Table 4 Continued















4 Discussion




















5 Conclusion




Acknowledgments


References






















Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy









4 Discussion




















5 Conclusion




Acknowledgments


References






















Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy





















5 Conclusion




Acknowledgments


References






















Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy





Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy




Estimates of Combining Ability and Heterosis for Yield and Its … · 2019. 7. 30. ·...

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Transcript of Estimates of Combining Ability and Heterosis for Yield and Its … · 2019. 7. 30. ·...