Avocado research at the E.E. la Mayora,

Malaga, Spain- Latitude: 36º 45’ N- Temperatures (last 40 years)

- Average: 19.4ºC:- 29.4ºC (average highs in August)- 9.3 ºC (average lows in January)- Lowest temp on record: 0.5ºC in

January 2005- Rainfall: 435 mm year

La Mayora Experimental Station

• Commercial avocado orchards started to be planted in the 1970s.

• Original  plantings:  seeds  imported  from Mexico  as  rootstocks  (Topa Topa)  and grafted  with  commercial  varieties  such  as Hass and Fuerte.

• Spain  produces  about  1/3  of  European consumption

• Current situation: • Rootstocks  obtained  from  seeds and Duke 7

• Main cultivar Hass (more than 70% of surface)  followed by Fuerte and Bacon

• Main problems: – soil  fungi:  Phytophthora and 

Rosellinia– Persea mite: Olygonichus perseae

AVOCADO IN SPAIN Main avocado research lines at the E.E. la Mayora 

Spanish Council for Scientific Research

LA MAYORA EXPERIMENTAL STATION

Optimization of avocado cultural techniques

Organic production:Study of the effects of low or no mineral N supply on yield, tree growth and fruit quality using different mulching applications

MicroelementsDifferent doses and soilaplication methods for B, Zn andCu have been evaluated for thelast 12 years.

Pruning:Different pruning dates in summerare being studied.

Alternate irrigation:Alternate irrigation is beingcompared with conventionalirrigation on yield, tree growth androot system development as a promising tool to control soil-borne diseases.

Postharvest management:Study of the effects of some T-RH combinations and different physicaland chemical treatments on fruitrots

Plant Material

Molecular fingerprintingFingerprinting of the germplasm collection: about 30 local and 60 foreign genotypes

Agronomic evaluation of different cultivarsA dynamic cultivar collection, including several Hass-likeselections from all over the world is being evaluated for traits of agronomic interest

Coefficient0.23 0.42 0.62 0.81 1.00

LACONSULA12MW

SAN JAVIER 13 LA CONSULA 12 SAN JAVIER 8 SAN JAVIER 19 SAN JAVIER 12 SAN JAVIER 1 SAN JAVIER 6 SAN JAVIER 11 SAN JAVIER 4 SAN JAVIER 29 SAN JAVIER 28 LA CONSULA 6 LA CONSULA 9 MEXICOLA SCOTT THOMAS BUENO LA PISCINA ALHAURIN BENTAVOL GAR DUKE PARENT DUKE 6 DUKE 7 FITO CHINEA BENTAVOL INV CUPANDA G6 SCHIDMT MARVEL (BL 516) BACON LULA SAN JAVIER 14 COÍN TOPA TOPAHARVEST LONHEIS SHIAPACASSE JIMENEZ 2 HASS MOTRIL EUGENIUM H670 HASS TACAMBARO JIMENEZ 1 SIR PRIZE OA184 FUNDACIÓN 2 REGAL ADI NOBEL (BL667) BL122 GEM BL5556 IRIET MONSALVE EL VISO VILLENA FUERTE ACUEDUCTOS RR86 COLIN V33 SHEPARD RINCOATL EDEN PINKERTON TORO CANYON NEGRA DE LA CRUZLONJAS SRA. CHINEA CLAVERO 2 MAOZ ANAHEIM GVAR13 FUSCH 20 G755A

Similarity0.23 0.42 0.62 0.81 1.00

LACONSULA12MW

SAN JAVIER 13 LA CONSULA 12 SAN JAVIER 8 SAN JAVIER 19 SAN JAVIER 12 SAN JAVIER 1 SAN JAVIER 6 SAN JAVIER 11 SAN JAVIER 4 SAN JAVIER 29 SAN JAVIER 28 LA CONSULA 6 LA CONSULA 9 MEXICOLA SCOTT THOMAS BUENO LA PISCINA ALHAURIN BENTAVOL GAR DUKE PARENT DUKE 6 DUKE 7 FITO CHINEA BENTAVOL INV CUPANDA G6 SCHMIDT MARVEL (BL 516) BACON LULA SAN JAVIER 14 COÍN TOPA TOPAHARVEST LOHNEI SSSHIAPACASSE JIMENEZ 2 HASS MOTRIL EUGENIM H670 HASS TACAMBARO JIMENEZ 1 SIR PRIZE OA184 FUNDACIÓN 2 REGAL ADI NOBEL (BL667) LAMB HASS (BL122) GEM BL5552 IRIET MONSALVE EL VISO VILLENA FUERTE ACUEDUCTOS RR86 COLIN V33 SHEPARD RINCOATL EDEN PINKERTON TORO CANYON NEGRA DE LA CRUZLONJAS S. CHINEA CLAVERO 2 MAOZ ANAHEIM GVAR13 FUCHS 20 G755A

6456

79

94

100

78

83

96 94

10057

58

6264 5250

100

100

9779

6745

Reproductive biology and optimization of yieldA correct understanding of the floral biology of avocado under our environmental conditions is necessary to optimize yield

Pollination: Effects of different pollinizers on alogamy rate and yield

Flower Quality: Study of the causes behind flower abscission: starch content of individual flowers at anthesis and itsrelation with flower fate

Study of the progamic phase and the effects of environment (temperature and humidity) on the dichogamous cycle

Incidence and development of strategies for the biological control of Persea mite

• Important pest in avocado in Spain since 2004

• Current studies directed towards evaluating the incidence of the pest and to develop adequate strategies ofbiological control.

• The presence of different types of pollen on avocado plants seems to increase phytoseiid populations in spring: pollen applications could be a promising tool to control mite populations in the field.

Optimization of genetic transformation

Fernando Pliego, University of Malaga

CHEMICAL CONTROL

GENETIC CONTROLUse of resistant / tolerant rootstocks

BIOLOGICAL CONTROLUse of antagonistic microorganisms which

reduce the disease (Sordaria, Thichoderma, bacterial strains)

REGULATION AND CULTURAL METHODS

Remove the infected plants, irrigation control, use of organic amendements

INTEGRATEDMANAGEMENT

SOLARIZATION

PHYSICAL CONTROL

Control of avocado white rot. Rosellinia necatrix

University of MalagaIFAPA

Phase 0: pruning of escape trees int he field

Phase I: establishmentin vitro

Phase II:proliferation

Phase III: rooting Phase IV: acclimatation

Multiplication in vitro of escape trees or seedlings

Selection of avocado rootstocks tolerant to Rosellinia necatrix

Avocado trees surviving in orchards infected with R. necatrix

Seedlings from different origins(Mexico, Australia, Spain)

Araceli BarceloIFAPA

Seedlings after inoculation

Artificially infested plot

RESEARCH ON AVOCADO REPRODUCTIVE BIOLOGY AT THE E.E. LA MAYORA, MÁLAGA SPAIN

♀ ♂

Overlap

Protogynousdichogamy

2 TYPES OF CULTIVARSA and B

AVOCADO CHARACTERIZED BY LOW FRUIT SET

Massive drop of flowers and developing fruitlets

Some unpollinated flowers Inadequate pollination

Other factors must be involved

OBJECTIVES

1.1. ENVIRONMENTAL FACTORS AFFECTING THE PROGAMIC PHASEENVIRONMENTAL FACTORS AFFECTING THE PROGAMIC PHASE

2. NUTRITIVE STATUS OF THE FLOWERS AT ANTHESIS2. NUTRITIVE STATUS OF THE FLOWERS AT ANTHESIS

3. EFFECT OF CROSS3. EFFECT OF CROSS--POLLINATION ON YIELD AND OUTCROSSINGPOLLINATION ON YIELD AND OUTCROSSING

4. OPTIMIZING THE CHOICE OF POLLINIZERS4. OPTIMIZING THE CHOICE OF POLLINIZERS

OBJECTIVES

1.1. ENVIRONMENTAL FACTORS AFFECTING THE PROGAMIC PHASEENVIRONMENTAL FACTORS AFFECTING THE PROGAMIC PHASE

2. NUTRITIVE STATUS OF THE FLOWERS AT ANTHESIS2. NUTRITIVE STATUS OF THE FLOWERS AT ANTHESIS

3. EFFECT OF CROSS3. EFFECT OF CROSS--POLLINATION ON YIELD AND OUTCROSSINGPOLLINATION ON YIELD AND OUTCROSSING

4. OPTIMIZING THE CHOICE OF POLLINIZERS4. OPTIMIZING THE CHOICE OF POLLINIZERS

Pollen adhesion and germination observed both in female and male stages

EFFECT OF TEMPERATURE ON POLLEN ADHESION AND

GERMINATION

No

adhe

red

polle

n gr

ains

Temperature

Field

Field

Temperature

% P

olle

n ge

rmin

atio

n

Female Male

Female Male

EFFECT OF RELATIVE HUMIDITY ON POLLEN

ADHESION AND GERMINATION

No

adhe

red

polle

n gr

ains

Female

Female

Male

Male

% P

olle

n ge

rmin

atio

n

Relative humidity

Relative humidity

Stigma

Style 1/4

Style 1/2

Style 3/4

Ovary

Ovule

Time after pollination (hours)

EFFECT OF TEMPERATURE ON POLLEN TUBE GROWTH

20oC

30oC

10oC

2 4 86 24 30 48hours

No temp effect on

ovule viability

% fruit set similar between on and off years

% fl

ower

s/fr

uits

set

% fl

ower

s/fr

uits

set

Weeks after end of flowering

Weeks after end of flowering

OBJECTIVES

1.1. ENVIRONMENTAL FACTORS AFFECTING THE PROGAMIC PHASEENVIRONMENTAL FACTORS AFFECTING THE PROGAMIC PHASE

2. NUTRITIVE STATUS OF THE FLOWERS AT ANTHESIS2. NUTRITIVE STATUS OF THE FLOWERS AT ANTHESIS

3. EFFECT OF CROSS3. EFFECT OF CROSS--POLLINATION ON YIELD AND OUTCROSSINGPOLLINATION ON YIELD AND OUTCROSSING

. OPTIMIZING THE CHOICE OF POLLINIZERS. OPTIMIZING THE CHOICE OF POLLINIZERS

I2KI

No.

of f

low

ers

Optical density x104

- NO EXTERNAL DIFFERENCES AMONG FLOWERS- GREAT DIFFERENCES IN STARCH CONTENT

1st Row

2nd Row

3rd Row

4th Row Opt

ical

den

sity

x10

4

Place in the inflorescence

1st row 2nd row 3rd row 4th row

Opt

ical

den

sity

x10

4

Early flowers Late flowers

Differences in starch content between two populations of flowers with different capacity to set fruits STARCH CONTENT IN INDIVIDUAL FLOWERS AND FRUIT SET

Opt

ical

den

sity

x10

4

Dropped Retained

OBJECTIVES

1.1. ENVIRONMENTAL FACTORS AFFECTING THE PROGAMIC PHASEENVIRONMENTAL FACTORS AFFECTING THE PROGAMIC PHASE

2. NUTRITIVE STATUS OF THE FLOWERS AT ANTHESIS2. NUTRITIVE STATUS OF THE FLOWERS AT ANTHESIS

3. EFFECT OF CROSS3. EFFECT OF CROSS--POLLINATION ON YIELD AND OUTCROSSINGPOLLINATION ON YIELD AND OUTCROSSING

4. OPTIMIZING THE CHOICE OF POLLINIZERS4. OPTIMIZING THE CHOICE OF POLLINIZERS

Background

Increase distance to the pollen donor source

Outcrossing rate Yield

(Vrecenas-Gadus and Ellstrans, 1985Goldring et al., 1987)

(Bergh and Gustafson, 1958Bergh and Garber, 1964Bergh et al., 1966Bergh, 1968)

Contradictory results Goldring et al., 1987Johannsmeier et al., 1989Garner et al., 2008

Selective fruit drop Most fruits in the tree result of cross-pollination

OUTCROSSING RATE IN AN SOLID HASS BLOCK OPPOSITE TO A SOLID FUERTE BLOCK

1034

956958

995997999

1038 1036

Hass

960

875879 877

Fuerte

20-30 fruits per tree: DNA extraction from the embryos

AVAG21

Hass186/201

Fuerte 183/203

Fuerte

Hass

SSR analysis

Pearson correlation coefficient

Cross‐fertilization Distance to the pollen source

‐0.7 (p= 0,014)

Row 1 Row 2 Row 3

Out

cros

sing

rate

p= 0,01

Row 1 Row 2 Row 3

Out

cros

sing

rate

No significant effect of the distance to the pollen source was found during 13 years

FRUIT DROP

July August

Mid fertil.

Early fertil.

85% 48%

% of cross-fertilization

% of dropped flowers related to date of fertilization

Hass Fuerte Hass Fuerte

Out

cros

sing

rate

Months after anthesis

OBJECTIVES

1.1. ENVIRONMENTAL FACTORS AFFECTING THE PROGAMIC PHASEENVIRONMENTAL FACTORS AFFECTING THE PROGAMIC PHASE

2. NUTRITIVE STATUS OF THE FLOWERS AT ANTHESIS2. NUTRITIVE STATUS OF THE FLOWERS AT ANTHESIS

3. EFFECT OF CROSS3. EFFECT OF CROSS--POLLINATION ON YIELD AND OUTCROSSINGPOLLINATION ON YIELD AND OUTCROSSING

4. OPTIMIZING THE CHOICE OF POLLINIZERS4. OPTIMIZING THE CHOICE OF POLLINIZERS

SEARCHING FOR A POLLINIZER FOR HASS

Requeriments

Type B

Overlap in flowering time with Hass

Currently in Spain Fuerte is used

Not enough overlap

If possible: Hass-like fruits

Study of the flowering season of 27 cultivars

VARIEDADES ADI HASS MOTRIL BL 5552 IRIET BL122 JIMENEZ I BL516 JIMENEZ II BL667 LONHEISS COLIN V-33 LONJAS EDEN NEGRA DE LA CRUZ FUERTE OA 184 FUNDACIÓN II PINKERTON H670 REGAL GEM (3-29-5) RINCOATL HARVEST RT 5176 HASS SHEPARD CUPANDA

FLOWERING TIME

MARZO ABRIL MAYO13 16 19 22 25 28 31 3 6 9 12 15 18 21 24 27 30 3 6 9 12 15 18 21

FUERTECUPANDASHEPARDBL 122BL 5552BL 516NEGRA DE LA CRUZRT 5176JIMÉNEZ 1REGALH 670HASS MOTRILLONHEISEDENJIMÉNEZ 2BL 667LONJAS3-29-5IRIETHASSRINCOATLPINKERTONHARVESTCOLIN V-33FUNDACIÓN IIOA 184ADI

MARCH APRIL MAY

OVERLAP BETWEEN SEXUAL STAGES

Two trees per cultivar studied

11 cultivars selected

CULTIVARES HASS FUERTE BL 667 (NOBEL) BL 516 (MARVEL) BL 122 3-29-5 (GEM) JIMÉNEZ 2 JIMÉNEZ 1 HASS T. MOTRIL TACAMBARO H 670

Flower stage followed every 2 hours: 8:00‐ 20:00

Sexual stage Overlap% Male flowers

% Female flowers

OVERLAP IN SEXUAL STAGES BETWEEN FLOWERS OF 11 CULTIVARS

HASS

FUERTE

NOBEL

MARVEL

LAMB HASS

GEM

JIMENEZ 2

JIMENEZ 1

LOHNEISS

HASS MOTRIL

TACAMBARO

H670

8:00 10:00 12:00 14:00 16:00 18:00 20:00

*

*

*

*

*

*

*

Estado femenino Estado masculinoFemale stage Male stage

OVERLAP AT THE BEGGINING OF FLOWERING SEASON

HASS

FUERTE

NOBEL

MARVEL

LAMB HASS

GEM

JIMENEZ 2

JIMENEZ 1

LOHNEISS

HASS MOTRIL

TACAMBARO

H670

8:00 10:00 12:00 14:00 16:00 18:00 20:00

*

*

*

*

*

*

*

Estado femenino Estado masculino

*

*

*Female stage Male stage

OVERLAP AT THE END OF THE FLOWERING SEASON

HASS

FUERTE

NOBEL

MARVEL

LAMB HASS

GEM

JIMENEZ 2

JIMENEZ 1

LOHNEISS

HASS MOTRIL

TACAMBARO

H670

8:00 10:00 12:00 14:00 16:00 18:00 20:00

*

*

*

*

*

*

Estado femenino Estado masculino

*

Male stageFemale stage

% Fruit set after hand-pollinations

BL 667 (NOBEL) 8,4%

BL 516 (MARVEL) 7,4%

FUERTE 2,8%

CONCLUSIONS

Avocado shows a fast progamic phase. This phase is clearly affect by environmental conditions: high temperatures increase pollen tube

growth and low temperatures increase the time required for fertilization

Under conditions of 20-25ºC and high relative humidity, the estigma conserves the capacity to allow germination and pollen tube growth in

the male stage, favoring self-pollination Differences in yield between on and off years are due to the intensity offlowering since fruit set % is not significantly different

The nutritive status of the pistil is related to the reproductive success ofthe flower, since differences are observed in starch content among

flowers at anthesis. Starch content is higher in flowers that will set fruit. Thus, the nutritive status of the flower seems to be a necessary condition,

but not the only one, for fruit set

The distance between two complementary cultivars (‘Hass’ and‘Fuerte’) has an effect on cross fertilization; however, there are no

differences in yield with increasing distance

The genotype of the embryo does not seem to be determinant in selectivefruit drop during the months following anthesis; the fruits that drop are

preferently those fertilized at the end of the ‘Hass’ flowering season. Those fruits are mainly the result of self-fertilization since no flowers of

‘Fuerte’ are present at the end of the ‘Hass’ flowering season

Taking into account the length of the flowering season, the overlapbetween sexual stages and yield, ‘Marvel’ (BL516) and ‘Nobel’ (BL667) could be interesting pollinizers for ‘Hass’ under our growing conditions