The Inflorescence and Fruit Peduncle as Indicators of Nitrogen Status of the Avocado Tree

A tissue analysis trial for the diagnosis of nitrogen level was performed during the 2001 growing season in Paine County, Metropolitan Region, Chile. Seven-year-old `Hass' avocado (Persea americana Mill.) trees were soil treated with urea at rates of 0, 333, 666, and 999 g N/tree, split in two applications (2 and 4 months after fruit set). Each treatment was applied to three randomly selected trees. Fifty spring flush leaves and fifteen fruit peduncles were taken per tree 4 months after application. Two months later, 70 panicles per tree were taken, and nitrogen concentration in these samples was determined by Kjeldahl digestion. Differences between treatments were better detected in peduncle and inflorescence samples than in leaf samples. The relationship between nitrogen dose and nitrogen concentration in the tissue was R2 = 0.67, 0.65, and 0.56 in peduncle, leaf, and inflorescence, respectively. Consequently, peduncle appears a promising tissue, probably better than leaf, for diagnosing the nitrogen status of avocado trees.

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The use of faecal nitrogen as an index for estimating the consumption of herbage by grazing animals

The Journal of Agricultural Science ◽

10.1017/s0021859600013666 ◽

1963 ◽

Vol 61 (1) ◽

pp. 33-43 ◽

Cited By ~ 11

Author(s):

G. W. Arnold ◽

M. L. Dudzinski

Keyword(s):

Organic Matter ◽

Nitrogen Concentration ◽

Linear Equations ◽

Slope Position ◽

Seasonal Differences ◽

Faecal Nitrogen ◽

Independent Variable ◽

Regression Relations ◽

The Relationship ◽

Better Than

Data from thirty-five digestibility trials with sheep in metabolism cages were used to investigate statistically the relationships between organic matter intake (I), faecal organic matter output (F), and the nitrogen concentration in faecal organic matter (N).The data fell easily into groups due to botanical or seasonal differences in the feed. These groups of data were homogeneous and provided highly significant linear equations of the forms I = bF + cFN and I = a + cFN. When compared these groups of data sometimes showed differences in slope, position or both. A quadratic expressionI = bF + cFN + dFN2was found to accommodate a majority of the data but to be less precise than I = a + cFN.A further expression incorporating N as an independent variable was also examined,I = a + cFN2 + eN.This expression, although far from being universally adequate, proved to be generally better than existing formulae. When applied to the data of Greenhalgh et. al. (1960), it substantially reduced heterogeneity between data for spring and data for summer pastures.Causes of variation in the relationship between organic-matter intake and nitrogen in faeces, and some of the hazards of extrapolation from empirical regression relations, are discussed.

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

HortScience ◽

10.21273/hortsci12437-17 ◽

2017 ◽

Vol 52 (12) ◽

pp. 1707-1715 ◽

Cited By ~ 2

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.

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Manipulation of shoot growth patterns in relation to early fruit set in ‘Hass’ avocado (Persea americana Mill.)

Scientia Horticulturae ◽

10.1016/0304-4238(93)90015-i ◽

1993 ◽

Vol 56 (2) ◽

pp. 147-156 ◽

Cited By ~ 10

Author(s):

T.Grant Thorp ◽

Margaret Sedgley

Keyword(s):

Shoot Growth ◽

Fruit Set ◽

Growth Patterns ◽

Persea Americana ◽

Hass Avocado

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

Scientia Horticulturae ◽

10.1016/j.scienta.2015.11.011 ◽

2016 ◽

Vol 198 ◽

pp. 125-131 ◽

Cited By ~ 11

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

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

New Zealand Plant Protection ◽

10.30843/nzpp.2010.63.6548 ◽

2010 ◽

Vol 63 ◽

pp. 214-218 ◽

Cited By ~ 1

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 (

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The Impact of Outcrossing on Yields of ‘Hass’ Avocado

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.133.5.648 ◽

2008 ◽

Vol 133 (5) ◽

pp. 648-652 ◽

Cited By ~ 8

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.

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The timing of flush development affects the flowering of avocado (Persea americana) and macadamia (Macadamia integrifolia × tetraphylla)

Australian Journal of Agricultural Research ◽

10.1071/ar04287 ◽

2005 ◽

Vol 56 (7) ◽

pp. 723 ◽

Cited By ~ 23

Author(s):

Trevor Olesen

Keyword(s):

Effective Means ◽

Persea Americana ◽

First Flush ◽

Winter Solstice ◽

Management Guidelines ◽

Macadamia Integrifolia ◽

The Difference ◽

Hass Avocado ◽

Better Than ◽

Canopy Management

Orchard trees of A4 macadamia (Macadamia integrifolia × tetraphylla) and Hass avocado (Persea americana) were thinned and tip-pruned at different times to generate a range of trees with different stages of leafy flush development. The stagger in the start of the first flush following pruning was repeated in the start of subsequent flushes, so pruning was an effective means of changing the phase of the cycle of flush development. The difference in phase affected flowering. In macadamia, over 80% of the variance in flowering was explained by regression against pruning time. Flowering ranged from 0 to 43% of tip-pruned branches, with the most profuse flowering on flushes appearing in July. In avocado, over 45% of the variance in flowering of the first flush following pruning, and over 35% of the second flush, was explained by regression against pruning time, with more flowering on those flushes starting nearer to the winter solstice. The control trees flowered better than the pruned trees but there was too little information to explain the difference. The macadamia control trees had less synchronised flushing than the pruned trees, and were not subject to internal thinning. The avocado control trees appeared to have a phase of flush development different from the pruned trees, with a summer flush commencing before the first pruning date and maturing before the maturation of the first post-pruning flushes. More research is needed for related canopy management guidelines.

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

Journal of Apicultural Science ◽

10.2478/jas-2018-0001 ◽

2018 ◽

Vol 62 (1) ◽

pp. 5-14 ◽

Cited By ~ 2

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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Economic Analysis of Irrigation and Fertilization Management of Avocados

HortScience ◽

10.21273/hortsci.31.1.156 ◽

1996 ◽

Vol 31 (1) ◽

pp. 156-159 ◽

Cited By ~ 2

Author(s):

Etaferahu Takele ◽

Jewell L. Meyer ◽

Mary L. Arpaia ◽

David E. Stottlemyer ◽

Guy W. Witney

Keyword(s):

High Water ◽

Persea Americana ◽

Size Category ◽

N Application ◽

Riverside County ◽

Medium Level ◽

Hass Avocado ◽

Irrigation Levels ◽

The Relationship ◽

Very High

The effect of integrated applications of various irrigation and fertilization rates on productivity (yield and size) and returns of the `Hass' avocado (Persea americana Mill.) have been analyzed from 1987 to 1991 in western Riverside County. Eighteen treatment combinations comprised of three irrigation levels [80%, 100%, and 120% crop water use (ETc)], three N fertilizer levels (0.16, 0.7, and 1.4 kg/tree per year), and Zn (0 and 0.2 kg/tree per year) were included in the analysis. Using a partial budgeting procedure, returns after costs were calculated for each treatment combination. Costs of treatments, harvesting, hauling, and marketing were subtracted from the value of the crop. The value of the crop was calculated as the sum of crop returns in each size category. Three years of data on the relationship between irrigation and N showed 1) irrigating at 80% ETc would be ineffective even at very high water prices; 2) for groves where 100% ETc is sufficient, its application with either low or medium N would be beneficial; and 3) at higher irrigation (120% ETc), N application should be at or beyond the medium level.

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