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 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 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 Prohexadione calcium controls shoot growth of pear trees

2017 ◽  
Vol 22 (1) ◽  
Author(s):  
Mateus Silveira Pasa ◽  
José Carlos Fachinello ◽  
Horacy Fagundes Da Rosa Júnior ◽  
Émerson De Franceschi ◽  
Flávio Giberto Herter ◽  
...  
Keyword(s):  
Shoot Growth ◽  
Block Design ◽  
Fruit Weight ◽  
Internode Length ◽  
Management Tool ◽  
Cross Sectional ◽  
Growing Seasons ◽  
Randomized Complete Block Design ◽  
Return Bloom ◽  
Prohexadione Calcium

The aim of this study was to evaluate the effects of prohexadione calcium (PCa) on vegetative growth and production of ‘Carrick’, ‘Packham’s’ and ‘William’s’ pear. The trial was performed at the experimental field of the Federal University of Pelotas, Capão do Leão, RS, Brazil (31º 52’ 00" S; 52º 21’ 24" W), during the growing seasons of 2011 and 2012. Treatments were applied to single-tree replications in a randomized complete block design with four replications as follows: Control (unsprayed), PCa (PCa - 750 g ha-1 i.a.). The application was split in four (187,5g ha-1 a.i. each) and three timings (250g ha-1 a.i. each) in the 2011 and 2012 growing seasons, respectively. The assessed parameters were: shoot length, trunk cross sectional area (TCSA) increment, number of nodes, internode length, pruning weight, number of fruits, average fruit weight, production per tree and return bloom. It was possible to conclude that application of PCa at 750 g. ha-1 a.i satisfactorily controls shoot growth through the reduction of internode length of ‘Carrick’, ‘Packham’s’ and ‘William’s’ pears. Besides, it was observed that return bloom is not negatively affected by PCa. So, this plant growth regulator is a potential management tool to reduce shoot growth and the need for pruning in pear orchards.

scholarly journals `Hass' Avocado Carbohydrate Fluctuations. I. Growth and Phenology

1999 ◽  
Vol 124 (6) ◽  
pp. 671-675 ◽  
Author(s):  
Xuan Liu ◽  
Paul W. Robinson ◽  
Monica A. Madore ◽  
Guy W. Witney ◽  
Mary Lu Arpaia
Keyword(s):  
Vegetative Growth ◽  
Shoot Growth ◽  
Soluble Sugar ◽  
Soluble Sugars ◽  
Dry Weight ◽  
Fruit Production ◽  
Persea Americana ◽  
Starch Concentration ◽  
Total Soluble Sugar ◽  
Hass Avocado

Seasonal fluctuations in nonstructural carbohydrates (starch and soluble sugars) were studied in `Hass' avocado (Persea americana Mill.) trees on `Duke 7' rootstock over a 2-year period in southern California. On a dry weight basis, total soluble sugar (TSS) concentrations ranged from 33.0 to 236.0 mg·g-1 dry weight and were high compared to starch concentration (2.0 to 109.0 mg·g-1 dry weight) in all measured organs (stems, leaves, trunks and roots). The seven carbon (C7) sugars, D-mannoheptulose and perseitol, were the dominant soluble sugars detected. The highest starch and TSS concentrations were found in stem tissues, and in stems, a distinct seasonal fluctuation in starch and TSS concentrations was observed. This coincided with vegetative growth flushes over both sampling years. Stem TSS and starch concentrations increased beginning in autumn, with cessation of shoot growth, until midwinter, possibly due to storage of photosynthate produced during the winter photosynthetic period. TSS peaked in midwinter, while starch increased throughout the winter to a maximum level in early spring. A second peak in stem TSS was observed in midsummer following flowering and spring shoot growth. At this time, stem starch concentration also decreased to the lowest level of the year. This complementary cycling between stem TSS and starch suggests that a conversion of starch to sugars occurs to support vegetative growth and flowering, while sugars produced photosynthetically may be allocated directly to support flowering and fruit production.

scholarly journals Yield, fruit quality, and survival of 'Pêra' sweet orange on eight rootstocks in tropical cohesive soils

2021 ◽  
Vol 56 ◽  
Author(s):  
Hélio Wilson Lemos de Carvalho ◽  
Luciana Marques de Carvalho ◽  
Adenir Vieira Teodoro ◽  
Inácio de Barros ◽  
Eduardo Augusto Girardi ◽  
...  
Keyword(s):  
Fruit Quality ◽  
Sweet Orange ◽  
Block Design ◽  
Cohesive Soil ◽  
Fruit Production ◽  
Fruit Yield ◽  
High Yield ◽  
Alternate Bearing ◽  
Yield Efficiency ◽  
Tree Survival

Abstract: The objective of this work was to determine the influence of eight rootstocks on the yield, fruit quality, and survival of 'Pêra CNPMF D6' sweet orange (Citrus sinensis) trees grown under rainfed conditions in a cohesive soil of the Brazilian Northeast. In 2014-2018, the yield, fruits, and survival of trees planted in 1997 were evaluated in a randomized complete block design. Yield was assessed using annual fruit production, yield efficiency, and the alternate bearing index. Tree survival was considered the percentage of plants that remained alive until 2018. Fruit quality was evaluated by physicochemical attributes. 'Cravo' confirmed its good yield performance. Despite the lower number of trees, the 'Mazoe' rough lemon rootstock induced the highest fruit yield. The 'Cravo' x 'Cleópatra' hybrid and 'Volkameriano' lemon favored the highest trees survival, whereas 'Indio' citrandarin and 'Cravo' lime resulted in intermediate levels. The 'San Diego' and 'Riverside' citrandarins induced shorter tree with a high yield efficiency and a higher alternate bearing index, respectively. Fruits with less juice and mass were induced, respectively, by 'Riverside' citrandarin and 'Volkameriano' lemon. It can be concluded that the 'Mazoe' rootstock induces a higher fruit yield and 'Cravo' x 'Cleópatra' and 'Volkameriano', a greater survival. In addition, all rootstocks, except 'Riverside' and 'Volkameriano', induce fruit that meet the minimum quality requirements.

scholarly journals Nitrogen Fertilization Strategies for the ‘Hass’ Avocado that Increase Total Yield Without Reducing Fruit Size

2016 ◽  
Vol 26 (4) ◽  
pp. 426-435 ◽  
Author(s):  
Jaime E. Salvo ◽  
Carol J. Lovatt
Keyword(s):  
Shoot Growth ◽  
Important Determinant ◽  
Total Yield ◽  
Fruit Size ◽  
Fertilizer Application ◽  
Persea Americana ◽  
Phenological Stages ◽  
Tree Phenology ◽  
Hass Avocado ◽  
N Demand

Effects of nitrogen (N) fertilizer application times and rates on ‘Hass’ avocado (Persea americana) yield and fruit size were determined to resolve whether a single dose of soil-applied N [1x N (25 lb/acre)] at each of the five key stages of tree phenology (January, April, July, August, and November) (control) was as efficacious as soil-applied 2x N (50 lb/acre) at one or two key stages or soil- or foliar-applied 3x N (75 lb/acre) at only one stage. All trees received soil-applied N at 125 lb/acre as ammonium nitrate (NH4NO3) annually; trees receiving 2x or 3x N received the remaining N divided evenly at the same phenological stages (months) as trees receiving five 1x N applications. The importance of supplying N during the summer, when June drop, exponential fruit growth, vegetative shoot growth, and floral initiation occur, was determined by testing soil-applied 0.8x N in July plus August only (40 lb/acre N as NH4NO3 annually). Application time proved an important determinant of total yield. Yield of commercially valuable size (CVS) fruit was correlated with total yield (r = 0.80, P < 0.0001). Four-year cumulative total yields were equal for trees receiving soil-applied 1x N at five key phenological stages and trees receiving soil-applied 2x N in April and 18.75 lb/acre N at the four other stages (months). However, trees receiving soil-applied 2x N in April plus November and only 8.3 lb/acre N in the three other months, in particular July and August, had significantly lower 4-year cumulative total yields (P = 0.0362). Additional evidence of the importance of meeting avocado tree N demand in the summer is that trees receiving only 40 lb/acre N split in July plus August produced 4-year cumulative total yields equal to trees receiving 25 lb/acre N at the five key phenological stages; lower annual N would reduce fertilizer expense and protect the environment.

scholarly journals Ten Cycles of Recurrent Selection for Fruit Yield, Earliness, and Quality in Three Slicing Cucumber Populations

1996 ◽  
Vol 121 (3) ◽  
pp. 362-366 ◽  
Author(s):  
Todd C. Wehner ◽  
Christopher S. Cramer
Keyword(s):  
Recurrent Selection ◽  
Block Design ◽  
Total Yield ◽  
Fruit Shape ◽  
Fruit Yield ◽  
Randomized Complete Block Design ◽  
Sib Families ◽  
Population Improvement ◽  
Marketable Fruit ◽  
Made In

Fruit yield, earliness, and quality have low to moderate heritability, but are traits of major importance in cucumber (Cucumis sativus L.). The objective of this study was to determine the changes made in those traits using recurrent selection in three slicing cucumber populations (NCMBS, NCES1, and NCBA1). During population improvement, one or two replications of 200 to 335 half-sib families were evaluated in the spring season for five traits: total, early, and marketable fruit per plot, fruit shape rating, and a simple weighted index (SWI = 0.2(total yield)/2 + 0.3(early yield) + 0.2(% marketable)/10 + 0.3(fruit shape). Families from each population were intercrossed in an isolation block during the summer season using remnant seeds of the best 10% selected using the index. Response was evaluated using a split-plot treatment arrangement in a randomized complete block design with 32 replications in each of two seasons (spring and summer). Whole plots were the three populations, and subplots were the 11 cycles (cycles 0 to 9 plus checks). We measured improvement in performance of the populations in a selected (spring) and unselected environment (summer). Significant gains were made for all traits in all populations over the 9 to 10 cycles of recurrent selection. Greatest progress was made for the NCMBS population, with an average of 37% gain from cycle 0 to 9 over all five traits. The trait where most progress was made was early yield, with an average of 63% gain from cycle 0 to 9 over the three populations.

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.

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