scholarly journals The Impact of Outcrossing on Yields of ‘Hass’ Avocado

2008 ◽  
Vol 133 (5) ◽  
pp. 648-652 ◽  
Author(s):  
Lauren C. Garner ◽  
Vanessa E.T.M. Ashworth ◽  
Michael T. Clegg ◽  
Carol J. Lovatt
Keyword(s):  
Microsatellite Markers ◽  
Fruit Set ◽  
Persea Americana ◽  
Primary Factor ◽  
Alternate Bearing ◽  
Fruit Abscission ◽  
Significant Relationships ◽  
Outcrossing Rates ◽  
Hass Avocado ◽  
The Impact

‘Hass’ avocado (Persea americana Mill.) is characterized by excessive flower and fruit abscission, resulting in extremely low fruit set. Low outcrossing rates might be a factor contributing to low yields. It is hypothesized that self-fertilized flowers and resulting fruit abscise at a much higher rate than fruit that are the product of outcrossing. However, significant relationships between outcrossing rates and yields have only been established in a few avocado studies. The objective of this research was to investigate the importance of outcrossing to yield in a commercial ‘Hass’ orchard containing ‘Bacon’, an effective pollinizer of ‘Hass’. Microsatellite markers were used to determine the rate of outcrossing of fruit persisting to harvest on ‘Hass’ trees. Experiments were conducted during sequential on- and off-crop years. During both years, outcrossing rates were not related to yield or alternate bearing. These results indicate that outcrossing was not the primary factor affecting flower and fruit persistence and ultimately yield in this orchard for the two sequential years of this research.

scholarly journals Outcrossing between ‘Bacon’ Pollinizers and Adjacent ‘Hass’ Avocado Trees and the Description of Two New Lethal Mutants

HortScience ◽  
2009 ◽  
Vol 44 (6) ◽  
pp. 1522-1526 ◽  
Author(s):  
Raymond J. Schnell ◽  
Cecile L. Tondo ◽  
J. Steven Brown ◽  
David N. Kuhn ◽  
Tomás Ayala-Silva ◽  
...  
Keyword(s):  
Microsatellite Markers ◽  
Persea Americana ◽  
Outcrossing Rate ◽  
Selfing Rate ◽  
Crop Species ◽  
Commercial Cultivars ◽  
Outcrossing Rates ◽  
Hass Avocado

Avocado (Persea americana Mill.) has an unusual flowering mechanism, diurnally synchronous protogynous dichogamy, that promotes crosspollination among avocado genotypes. In commercial groves, which usually contain pollinizer rows adjacent to the more desirable commercial cultivars, the rate of outcrossing has been measured with variable results. Using microsatellite markers, we estimated outcrossing in a commercial California ‘Hass’ avocado orchard with adjacent ‘Bacon’ pollinizers. Seedlings grown from mature harvested fruit of both cultivars were genotyped with five fully informative microsatellite markers and their parentage determined. Among the 919 seedlings of ‘Hass’, 688 (75%) were hybrids with ‘Bacon’; the remaining 231 (25%) seedlings were selfs of ‘Hass’. Among the 850 seedlings of ‘Bacon’, 382 (45%) were hybrids with ‘Hass’ and the remaining 468 (55%) seedlings were selfs of ‘Bacon’. The high outcrossing rate observed in the ‘Hass’ seedlings was expected, because adjacent rows of opposite flowering types (A versus B) are expected to outcross. However, the high selfing rate in ‘Bacon’ was unexpected. A previous study in Florida using the cultivars ‘Simmonds’ and ‘Tonnage’ demonstrated differences in outcrossing rates between complementary flowering type cultivars. In both Florida and California, the A type parents (‘Hass’ and ‘Simmonds’) had similar outcrossing rates (≈75%); however, the B type parents (‘Bacon’ and ‘Tonnage”) had highly skewed outcrossing rates of 45% and 96%, respectively. Two new avocado lethal mutants were discovered among the selfed seedlings of ‘Hass’ and ‘Bacon’. These were labeled “spindly” and “gnarly” and are similar in phenotype to mutants described in Arabidopsis and other crop species.

scholarly journals The Relationship Between Flower and Fruit Abscission and Alternate Bearing of ‘Hass’ Avocado

2008 ◽  
Vol 133 (1) ◽  
pp. 3-10 ◽  
Author(s):  
Lauren C. Garner ◽  
Carol J. Lovatt
Keyword(s):  
Developmental Stages ◽  
Weather Conditions ◽  
Nutrient Status ◽  
Persea Americana ◽  
Alternate Bearing ◽  
Immature Fruit ◽  
Fruit Abscission ◽  
Reproductive Structures ◽  
Independent Process ◽  
Hass Avocado

Despite profuse flowering, ‘Hass’ avocado (Persea americana Mill.) yields are low because of excessive flower and fruit abscission. Whether the dynamics of flower and fruit abscission are influenced by or contribute to alternate bearing, the production of a heavy on-crop followed by a light off-crop that is characteristic of many avocado cultivars, remains unresolved. The objective of this research was to determine whether abscission of reproductive structures from ‘Hass’ avocado trees during specific developmental stages, including flowering, fruit development, and fruit maturity, was influenced by crop status of the current or preceding year. Abscised reproductive structures were collected from commercially bearing trees during two complete crop years. Flower abscission began at about the same time but peaked 1 month later in the off-crop year compared with the on-crop year. Peak abscission rates were lower during the off-crop year than the on-crop year (compare 1836 ± 403 to 5378 ± 856 flowers per day and 50 ± 18 to 280 ± 23 immature fruit per day, respectively). The off- or on-crop status of the tree did not influence the percentage fruit set, average fruit diameter, or biomass of individual fruit that abscised at similar phenological stages. Furthermore, flower and fruit abscission were not influenced by the number of mature fruit from the previous year's crop. In both years of the research, as immature fruit abscission declined, abscission of the preceding year's crop increased, indicating that the processes were controlled independently. During the study, neither weather conditions nor tree nutrient status were associated with key abscission events. Taken together, these results provide evidence that the previous year's yield does not influence flower or fruit abscission and the seasonal abscission of reproductive structures is an independent process that does not contribute to alternate bearing of ‘Hass’ avocado.

scholarly journals Optimal Nutrient Concentration Ranges of ‘Hass’ Avocado Cauliflower Stage Inflorescences—Potential Diagnostic Tool to Optimize Tree Nutrient Status and Increase Yield

HortScience ◽  
2017 ◽  
Vol 52 (12) ◽  
pp. 1707-1715 ◽  
Author(s):  
Salvatore Campisi-Pinto ◽  
Yusheng Zheng ◽  
Philippe E. Rolshausen ◽  
David E. Crowley ◽  
Ben Faber ◽  
...  
Keyword(s):  
Nutrient Concentration ◽  
Fruit Set ◽  
Fruit Size ◽  
Nutrient Status ◽  
Persea Americana ◽  
Nutrient Concentrations ◽  
Full Bloom ◽  
Nutrient Analysis ◽  
Tree Phenology ◽  
Hass Avocado

Optimizing ‘Hass’ avocado (Persea americana Mill.) tree nutrient status is essential for maximizing productivity. Leaf nutrient analysis is used to guide avocado fertilization to maintain tree nutrition. The goal of this research was to identify a ‘Hass’ avocado tissue with nutrient concentrations predictive of yields greater than 40 kg of fruit per tree. This threshold was specified to assist the California avocado industry to increase yields to ≈11,200 kg·ha−1. Nutrient concentrations of cauliflower stage inflorescences (CSI) collected in March proved better predictors of yield than inflorescences collected at full bloom (FBI) in April, fruit pedicels (FP) collected at five different stages of avocado tree phenology from the end of fruit set in June through April the following spring when mature fruit enter a second period of exponential growth, or 6-month-old spring flush leaves (LF) from nonbearing vegetative shoots collected in September (California avocado industry standard). For CSI tissue, concentrations of seven nutrients, nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), sulfur (S), zinc (Zn), and copper (Cu) were predictive of trees producing greater than 40 kg of fruit annually. Conditional quantile sampling and frequency analysis were used to identify optimum nutrient concentration ranges (ONCR) for each nutrient. Optimum ratios between nutrient concentrations and yields greater than 40 kg per tree were also derived. The high nutrient concentrations characterizing CSI tissue suggest current fertilization practices (timing or amounts) might be causing nutrient imbalances at this stage of avocado tree phenology that are limiting productivity, a possibility that warrants further investigation. Because CSI samples can be collected 4–6 weeks before full bloom, nutritional problems can be addressed before they affect flower retention and fruit set to increase current crop yield, fruit size, and quality. Thus, CSI nutrient analysis warrants further research as a potential supplemental or alternative tool for diagnosing ‘Hass’ avocado tree nutrient status and increasing yield.

Carbohydrate and boron content of styles of ‘Hass’ avocado ( Persea americana Mill.) flowers at anthesis can affect final fruit set

2016 ◽  
Vol 198 ◽  
pp. 125-131 ◽  
Author(s):  
H.L. Boldingh ◽  
M.L. Alcaraz ◽  
T.G. Thorp ◽  
P.E.H. Minchin ◽  
N. Gould ◽  
...  
Keyword(s):  
Boron Content ◽  
Fruit Set ◽  
Persea Americana ◽  
Hass Avocado

scholarly journals Factors affecting Hass avocado (Persea americana) fruit set in New Zealand

2010 ◽  
Vol 63 ◽  
pp. 214-218 ◽  
Author(s):  
L.J. Evans ◽  
R.M. Goodwin ◽  
H.M. McBrydie
Keyword(s):  
New Zealand ◽  
Fruit Set ◽  
Persea Americana ◽  
Factors Affecting ◽  
Hass Avocado

Avocado trees typically have a low (

scholarly journals An Econometric Demand Model for Florida Green-skin Avocados

2015 ◽  
Vol 25 (3) ◽  
pp. 405-411 ◽  
Author(s):  
Edward A. Evans ◽  
Fredy H. Ballen
Keyword(s):  
The United States ◽  
Persea Americana ◽  
Demand Model ◽  
Long Run ◽  
Recent Outbreak ◽  
Production Area ◽  
Price Flexibility ◽  
The Mean ◽  
Hass Avocado ◽  
The Impact

This article develops an inverse demand model for Florida green-skin avocados (Persea americana). Information from the model is used to assess the likely impact on growers’ prices resulting from a reduction in the supply of Florida green-skin avocados due to a recent outbreak of a deadly fungus in the Florida commercial avocado production area. Consideration is also given to the increased supply of green-skin avocados imported to the United States from the Dominican Republic (DR), as well as the increased availability of ‘Hass’ avocado in the U.S. market. The estimated own price flexibility of –0.551 evaluated at the mean suggests that Florida avocado prices are not very responsive to changes in quantity supplied. A reduction in the quantity supplied is likely to bring about a less than proportionate rise in the price. Moreover, any noticeable rise in prices due to the impact of the disease is likely to be short lived and may be insufficient to cover additional grove management costs. In the longer run, prices are expected to revert closer to their long-run trend (or decrease) as a result of increased shipments from the DR, and further increases in the availability of ‘Hass’ avocados.

scholarly journals Influence of gibberellin inhibitors applied during flowering of nonirrigated 'Hass' avocado trees

2018 ◽  
Vol 53 (8) ◽  
pp. 918-923 ◽  
Author(s):  
Bruna do Amaral Brogio ◽  
Simone Rodrigues da Silva ◽  
Tatiana Cantuarias-Avilés ◽  
Sérgio Figueiredo Angolini ◽  
Edypol Guilherme Baptista ◽  
...  
Keyword(s):  
Shoot Growth ◽  
Block Design ◽  
Fruit Shape ◽  
Persea Americana ◽  
Fruit Yield ◽  
Gibberellin Biosynthesis ◽  
Alternate Bearing ◽  
Water Control ◽  
Hass Avocado ◽  
Prohexadione Calcium

Abstract: The objective of this work was to evaluate the effect of different gibberellin biosynthesis inhibitors on shoot growth above the panicle, as well as on fruit yield, size, and shape of nonirrigated 'Hass' avocado (Persea americana) trees. The experiment was carried out in a randomized complete block design, with five treatments, four replicates, and 40 trees. From 2013 to 2015, the following treatments were applied at full bloom, as foliar sprayings: water (control), 250 mg L-1 prohexadione-calcium, 2,500 mg L-1 trinexapac-ethyl, 1,750 mg L-1 paclobutrazol, and 350 mg L-1 uniconazole; the first two are acylcyclohexanediones and the last two, triazoles. Fruit yield, yield efficiency, and alternate bearing were not affected by the application of plant growth regulators. However, the gibberellin inhibitors increased fruit size and modified the fruit shape of nonirrigated 'Hass' avocado. Uniconazole reduces shoot growth above the panicle, and this effect may vary depending on environmental conditions, especially water supply.

scholarly journals Use of GA3 to Manipulate Flowering and Yield of `Hass' Avocado

2000 ◽  
Vol 125 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Samuel Salazar-García ◽  
Carol J. Lovatt
Keyword(s):  
Early Stage ◽  
Persea Americana ◽  
Yield Reduction ◽  
Alternate Bearing ◽  
Concomitant Increase ◽  
Vegetative Shoot ◽  
Inflorescence Development ◽  
Initial Development ◽  
Shoot Number ◽  
Hass Avocado

Avocado trees (Persea americana Mill.) bearing a heavy crop produce a light “off” bloom the next spring. This results in a light crop and a subsequent intense “on” bloom the year after. The objective of the study was to quantify the effects of GA3 canopy sprays applied to `Hass' avocado trees during the months preceding an “off” or “on” bloom on inflorescence and vegetative shoot number and yield. The experiment was initiated approximately seven months before an anticipated “off” bloom in an attempt to increase flowering intensity and yield. GA3 (25 or 100 mg·L-1) was applied to separate sets of trees in September (early stage of inflorescence initiation), November (early stage of inflorescence development), January (initial development of the perianth of terminal flowers), March (cauliflower stage of inflorescence development; only 25 mg·L-1), or monthly from September through January (only 25 mg·L-1). Control trees did not receive any treatment. GA3 (100 mg·L-1) applied in September reduced inflorescence number in both years, but not yield. GA3 (25 or 100 mg·L-1) applied in November before the “on” bloom reduced inflorescence number with a concomitant increase in vegetative shoot number and 47% yield reduction compared to control trees. This treatment might provide avocado growers with a tool to break the alternate bearing cycle by reducing yield in an expected “on” crop year to achieve a higher yield the following year. GA3 (25 mg·L-1) applied in November or January stimulated early development of the vegetative shoot of indeterminate inflorescences. January and March applications did not affect the number of flowering or vegetative shoots produced either year. GA3 (25 mg·L-1) applied in March at the start of an “off” bloom increased 2-fold the production of commercially valuable fruit (213 to 269 g per fruit) compared to the control.

scholarly journals Effect of Honey Bee (Apis mellifera L.) Density on Pollination and Fruit Set of Avocado (Persea americana Mill.) Cv. Hass.

2018 ◽  
Vol 62 (1) ◽  
pp. 5-14 ◽  
Author(s):  
Juan F. Peña ◽  
Arturo Carabalí
Keyword(s):  
Apis Mellifera ◽  
Honey Bee ◽  
Fruit Set ◽  
Fruit Weight ◽  
Persea Americana ◽  
Pollination Efficiency ◽  
Final Number ◽  
Hass Avocado

Abstract The objective of this research was to determine the effect of honeybee density on pollination and fruit set of the Hass avocado. The research was carried out in the municipality of Popayán, Colombia. Three avocado orchards were selected, each one with an area of one hectare and trees with an age of six years. The treatments were: 1) four hives/ha, 2) six hives/ha, and 3) control without hives. Treatments of six and four hives/ha presented significant differences with respect to the control, with a honeybee density per tree of 7.72, 6.04 and 2.72, pollination rate of 60, 55 and 50%, pollination efficiency of 7.57, 6.04 and 5.98 grains of pollen per stigma, 6.11, 4.13 and 3.54% fruit set initial, 0.058, 0.048 and 0.028% fruit set final, 231, 212 and 137 of fruits per tree, 46.2, 38.2 and 21.6 kg fruit per tree, respectively. The results obtained show an increase of honey-bee density per tree, pollination rate, pollination efficiency, % fruit set, % fruit set final, number of fruits per tree and total fruit weight per tree when six and four bee hives/ha are introduced in the avocado crop.

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