scholarly journals Individual Shoot Defoliation Minimally Affects Pecan Return Bloom

HortScience ◽  
2013 ◽  
Vol 48 (3) ◽  
pp. 314-317
Author(s):  
Michael W. Smith ◽  
Becky S. Cheary
Keyword(s):  
Cultural Practices ◽  
Carya Illinoinensis ◽  
Alternate Bearing ◽  
Current Season ◽  
Fruit Thinning ◽  
Return Bloom

Alternate bearing of pecan [Carya illinoinensis (Wangenh.) K. Koch] remains the leading problem of the industry. Several cultural practices have been developed or improved to mitigate alternate bearing. Premature defoliation was one problem identified that substantially decreased return bloom. The objective of this study was to determine the response of individual shoots exposed to various defoliation treatments. In one study, individual vegetative or bearing shoots were hand-defoliated in mid-September. Defoliation was the basal one-half, distal one-half, entire shoot, or not defoliated. Another study applied the same defoliation treatments to bearing shoots in July, August, or September. Defoliation had minimal effects on return bloom and rarely affected the percentage of current-season shoots fruiting the next year. Defoliation date also had little effect on return bloom. These data indicate that individual shoot response to defoliation was not autonomous and has implications for determining crop overload and needed mechanical fruit thinning.

scholarly journals Native Variation in Bloom and Crop Density in Spur-type `Delicious' and Effect of Ethephon Applied in High Crop Years

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1096D-1097
Author(s):  
Martin J. Bukovac ◽  
Jerry Hull ◽  
Paolo Sabbatini
Keyword(s):  
Apple Tree ◽  
Cultural Practices ◽  
Total Yield ◽  
Fruit Size ◽  
Alternate Bearing ◽  
Full Bloom ◽  
Crop Load ◽  
Fruit Thinning ◽  
Crop Density ◽  
Return Bloom

For studies on blossom/fruit thinning in apple, tree selection is often based on uniformity of bloom/crop load, assuming that such trees exhibit greater uniformity to treatment. However, the literature is replete with data showing marked variation for a given treatment. We followed variation in bloom/crop density of spur-type `Delicious'/MM.106 and effect of ethephon applied in high crop years on return bloom/yield. Uniform trees (n = 95), under identical cultural practices, were selected for varying crop load. Return bloom, yield and fruit size were monitored over six years. General mean (X) for yield was 94 ± 25 kg/tree and bloom density, rated 1 to 10 (highest), was 5.4 ± 1.7. Annual yield deviated from X by +56 to –40% and bloom density by +49 to –42%. All trees were ranked (decreasing yield) and assigned to five percentile (PCTL) groups (1st, 81-100; 2nd, 61-80; 3rd, 41-60; 4th, 21-40; 5th, 0-20 kg/tree). Trees in each group were reassigned annually to the five PCPL groups for the next five years. Of trees in 1st PCTL (n = 19, X = 187 ± 10 kg/tree) in year one, 5, 5, 24, 0 and 63% placed in PCPL 1, 2, 3, 4, and 5, respectively, in year two. Of trees in 1st PCTL (5%) in year two, all placed in PCTL 2 in year three. Effect of ethephon [200 mg·L-1 at 3, 3 + 6, 3 + 6 + 9 weeks after full bloom (WAFB)] applied in on years to `Redchief', with strong alternate bearing, were evaluated for six years. Ethephon at 3 WAFB had no effect. Yield from multiple applications differed from control (NTC) in off years, but not from each other. Total yield (3 on + 3 off years) for the NTC and ethephon at 3 + 6 WAFB was similar (479 vs. 471 kg/tree). However, 64% of the total yield was produced in the on years and 36% in the off years in NTC vs. 56 and 44% in 3 + 6 WAFB, respectively.

scholarly journals Influence of Cluster Thinning on Return Bloom, Nut Quality, and Concentrations of Potassium, Nitrogen, and Non-structural Carbohydrates

2007 ◽  
Vol 132 (2) ◽  
pp. 158-165 ◽  
Author(s):  
Charles T. Rohla ◽  
Michael W. Smith ◽  
Niels O. Maness
Keyword(s):  
Lateral Position ◽  
Limiting Factors ◽  
Nonstructural Carbohydrates ◽  
Alternate Bearing ◽  
Terminal Position ◽  
Current Season ◽  
Fruit Thinning ◽  
Second Growth ◽  
Return Bloom ◽  
One Year

Alternate bearing pecan trees [Carya illinoinensis (Wangenh.) C. Koch] were hand-thinned annually to 1, ≤2, or ≤3 fruit/cluster or not thinned when the ovule was about one-half expanded. Return bloom was monitored on (1) vegetative shoots, (2) bearing shoots without a second growth flush in the terminal position on 1-year-old branches, (3) bearing shoots without a second growth flush in the lateral position on 1-year-old branches, and (4) bearing shoots with a second growth flush that were primarily in the terminal position. Yield and nut quality were determined in addition to nonstructural carbohydrate, organically bound nitrogen (N), and potassium (K) concentrations in the roots and shoots during January. Fruit thinning improved return bloom but had little effect on weight/nut, kernel percent, or kernel grade. Fruit thinning had either a modest or no effect on nonstructural carbohydrates, organically bound N, and K concentrations. Vegetative shoots and bearing terminal shoots produced a similar number of flowers/1-year-old branch and percentage of flowering current-season shoots. Bearing lateral shoots produced fewer flowers than vegetative shoots most years and fewer flowering current-season shoots during one year. Shoots with a second growth flush produced more flowers/1-year-old branch and a larger percentage of flowering current-season shoots than did vegetative shoots 2 of 3 years. These data indicate fruit thinning of overloaded trees improved return bloom, but the lack of interactions between thinning treatment and shoot type suggests that the number of fruit/cluster was less important than total crop load in determining nut quality and return bloom. Thus removal of entire fruit clusters appears as effective as thinning fruit within a cluster to maintain adequate nut quality and promote return bloom. Nonstructural carbohydrates, organically bound N, and K were not limiting factors in bearing consistency because they were not depressed in unthinned trees. Nonstructural carbohydrates, organically bound N, and K concentrations were not closely linked to alternate bearing because return bloom was enhanced by thinning, but thinning did not affect their concentrations.

scholarly journals Correlations of Crop Load and Return Bloom with Root and Shoot Concentrations of Potassium, Nitrogen, and Nonstructural Carbohydrates in Pecan

2007 ◽  
Vol 132 (1) ◽  
pp. 44-51 ◽  
Author(s):  
Michael W. Smith ◽  
Charles T. Rohla ◽  
Niels O. Maness
Keyword(s):  
Growth Regulator ◽  
Current Theory ◽  
Nonstructural Carbohydrates ◽  
Alternate Bearing ◽  
Crop Load ◽  
Current Season ◽  
Flower Production ◽  
Previous Season ◽  
Second Growth ◽  
Return Bloom

The current theory of pecan [Carya illinoinensis (Wangenh.) C. Koch] alternate bearing is the “growth regulator–carbohydrate theory” in which flowering is first controlled by growth regulators produced by fruit and leaves, and then by the size of the carbohydrate pool near budbreak. Lack of nitrogen (N) reserves has also been proposed to be limiting after large crops, thus reducing return bloom. Annual production was determined for 12 individual trees for 3 years. Return bloom was monitored on four previous-season shoot types: 1) vegetative shoots, 2) bearing terminal shoots without a second growth flush, 3) bearing lateral shoots without a second growth flush, and 4) bearing shoots that were primarily in the terminal position with a second growth flush. Nonstructural carbohydrates, organically bound N, and potassium (K) concentrations were determined in roots and shoots. Regression analysis was used to determine the effect of yield on subsequent nonstructural carbohydrates, N, and K in the roots and shoots, and their postyield concentrations on subsequent flowering. Alternate bearing was evident because there were reductions of 18%, 16%, and 18% in the percentage of current season shoots flowering for every 10 kg/tree production increase in the previous season's yield in 2002, 2003, and 2004 respectively. Flower production in 2002 decreased by 2.6 flowers/1-year-old branch and 1.6 flowers/1-year-old branch in 2003 for each 10 kg/tree increase in production. The third year of the study, neither previous season shoot type nor yield affected subsequent flower production. The previous year's shoot type did not affect the percentage of current season shoots flowering; however, the previous year's shoots that had a second growth flush produced more flowers the following year than the other shoot types. Results suggested that crop load was not related to nonstructural carbohydrates, N, or K in the roots and shoots during January in these well-managed trees. Stored nonstructural carbohydrates, N, and K were also not related to return bloom. These data suggest that the current “growth regulator–carbohydrate theory” may not be valid in these well-managed trees. Nonstructural carbohydrates, K, and organically bound N do not appear to be critical factors regulating flowering.

scholarly journals The Effects of Exogenous Bioregulators and Environment on Regular Cropping of Apple

1999 ◽  
Vol 9 (3) ◽  
pp. 323-327 ◽  
Author(s):  
Kathleen M. Williams ◽  
Esmaeil Fallahi
Keyword(s):  
Environmental Factors ◽  
Cultural Practices ◽  
Negative Impact ◽  
Fruit Size ◽  
The United States ◽  
Physiological Status ◽  
Naphthalene Acetic Acid ◽  
Alternate Bearing ◽  
Return Bloom ◽  
Production Areas

The use of exogenous plant bioregulators or plant hormones to adjust crop load in apple (Malus ×domestica Borkh.) and promote regular cropping remains challenging to both researchers and producers. Responses to these hormones are sensitive to the rate and timing of application, to physiological status of the tree, orchard system, variety, rootstock, and a myriad of cultural practices and environmental factors. Of the environmental factors, temperature plays the most important role in determining response and efficacy of a given material. All classes of plant bioregulators have been used over the past 30 to 40 years as postbloom chemical thinning materials. Most of the standard postbloom thinning programs involve application of a synthetic auxin, such as naphthalene acetic acid (NAA) in combination with carbaryl (Sevin), a commonly used insecticide. The mode of action of these two compounds is not clearly understood. Gibberellins generally have not been effective thinning materials for apple because of their negative impact on return bloom. Ethylene-releasing compounds have been used successfully as postbloom thinning materials. Cytokinins, particularly synthetic sources such as 6-benzyladenine (6-BA), have been shown to effectively thin fruit and enhance fruit size on many commercial varieties. The rate and timing of 6-BA applications are critical to obtain desirable thinning and fruit size responses. The use of these different bioregulators is essential for regular cropping of apple, particularly for spur `Delicious', `Fuji' and other varieties that are difficult to thin chemically and which are prone to severe alternate bearing. The focus of this discussion is the use of these bioregulators in commercial apple production areas in the United States.

scholarly journals A Comparison of Return Bloom and Nonstructural Carbohydrates, Nitrogen, and Potassium Concentrations in Moderate and Severe Alternate-bearing Pecan Cultivars

2007 ◽  
Vol 132 (2) ◽  
pp. 172-176 ◽  
Author(s):  
Charles T. Rohla ◽  
Michael W. Smith ◽  
Niels O. Maness ◽  
William Reid
Keyword(s):  
Lateral Position ◽  
Carya Illinoinensis ◽  
The Other ◽  
Unique Characteristic ◽  
Nonstructural Carbohydrates ◽  
Alternate Bearing ◽  
Terminal Position ◽  
Nonstructural Carbohydrate ◽  
Return Bloom

The most significant horticultural problem facing pecan producers is alternate bearing. Four pecan [Carya illinoinensis (Wangenh.) C. Koch] cultivars were chosen, two with low to moderate and two with severe alternate-bearing tendencies, to compare selected characteristics related to irregular bearing. The cultivars were Colby and Peruque (low to medium alternate-bearing tendency) and Osage and Giles (high alternate-bearing tendency). Vegetative shoots and fruit-bearing shoots in the terminal and lateral position on 1-year-old branches were tagged in October, and flowering was determined the next spring. Shoot and root samples were collected while dormant and then analyzed for organically bound nitrogen (N), potassium (K), and nonstructural carbohydrate concentrations. As expected, ‘Colby’ and ‘Peruque’ had a lower alternate-bearing tendency than ‘Giles’ and ‘Osage’. Cultivars with a low alternate-bearing tendency had a larger return bloom on the bearing shoots in the terminal position than the other shoot types. Cultivars with a high alternate-bearing tendency had a lower return bloom on bearing terminal shoots than vegetative shoots. Bearing shoots in the lateral position usually had a lower return bloom than the other shoot types regardless of cultivar. Neither root nor shoot N, K, or nonstructural carbohydrate concentrations appeared to be closely related to the alternate-bearing characteristics of the four cultivars. The unique characteristic identified for low alternate-bearing cultivars was their ability to produce as many or more flowers and flowering shoots the next year on previously bearing terminal shoots compared with previously vegetative shoots. In high alternate-bearing cultivars, return bloom of bearing terminal shoots was suppressed relative to their vegetative shoots.

scholarly journals Fruit-removal Time Influences Return Bloom in Pecan

HortScience ◽  
1993 ◽  
Vol 28 (8) ◽  
pp. 800-802 ◽  
Author(s):  
William Reid ◽  
Susan M. Huslig ◽  
Michael W. Smith ◽  
Niels O. Maness ◽  
Julia M. Whitworth
Keyword(s):  
Carya Illinoinensis ◽  
Fruit Removal ◽  
Optimum Time ◽  
Feasible Method ◽  
Fruit Thinning ◽  
Removal Time ◽  
Return Bloom ◽  
Water Stage ◽  
Dough Stage

The optimum time for removing pecans [Carya illinoinensis (Wangenh.) K. Koch] to enhance return bloom was determined. Fruit were removed from part of `Mohawk', `Giles', and `Gormely' trees five times during the season as determined by fruit phonological age: immediately after postpollination drop, at 50% ovule expansion, at 100% ovule expansion or water stage, during the onset of dough stage, and 2 weeks after dough stage. Return bloom of all cultivars was increased by fruit removal during ovule expansion. Removing `Mohawk' and `Giles' fruit shortly after pollination induced the greatest return bloom. Return bloom in the small-fruited `Gormely' was equally stimulated by fruit removal at any time during ovule expansion, a result indicating that early fruit removal may be more important for large-than for small-fruited cultivars. If a commercially feasible method to thin pecans is developed, our studies indicate that the optimum time for fruit thinning would be during ovule expansion.

scholarly journals Production Technology of Peach, Plum and Apricot in India

Prunus ◽  
2020 ◽  
Author(s):  
Bhende Siddhesh Shamrao
Keyword(s):  
Production Technology ◽  
Weed Management ◽  
Cultural Practices ◽  
Cropping Systems ◽  
Harvest Management ◽  
Alternate Bearing ◽  
Pests And Diseases ◽  
Fruit Thinning ◽  
After Care ◽  
Training And Pruning

In this chapter production technology of peach, plum and apricot in India is elaborated in detail in relation to introduction, origin and distribution of crop, importance and uses, morphological features of tress, other related species involved, climate and soil requirement, varieties, propagation and raising of rootstocks, planting and planting densities, cropping systems, manure and fertilisers application, cultural practices, weed management, orchard floor management, after care training and pruning, pollination and pollinizers, flowering and crop regulation, use of growth regulators, fruiting in the crop, fruit thinning and drop, maturity and harvesting, post-harvest management, handling and storage, insects, pests and diseases, special production problems like low productivity, unfruitfulness and self-incompatibility, premature leaf fall, replant problem, alternate bearing and remedies and physiological disorders of the crop.

scholarly journals Fruit Production Characteristics of ‘Pawnee’ Pecan

HortScience ◽  
2012 ◽  
Vol 47 (4) ◽  
pp. 489-496
Author(s):  
Michael W. Smith
Keyword(s):  
Fruit Production ◽  
Quality Characteristics ◽  
Kernel Weight ◽  
Carya Illinoinensis ◽  
Alternate Bearing ◽  
Shell Weight ◽  
Current Season ◽  
Optimum Yield ◽  
Optimum Production ◽  
Production Characteristics

Yield and selected nut quality characteristics were monitored on hedge pruned ‘Pawnee’ pecan [Carya illinoinensis (Wangenh.) K. Koch.] trees over a 5-year period to characterize optimum production defined as equal crops 2 successive years. Previous year yield was linearly or quadratically related to current-season yield in three of four instances. Optimum yield ranged from 18 kg/tree to 29 kg/tree among years. Weight/nut, weight/kernel, and percent kernel were negatively related to yield/tree. Weight/nut and weight/kernel were more closely related to yield/tree than percent kernel, indicating that as cropload increased, shell weight and kernel weight were disproportionately affected. Increasing croploads reduced kernel weight more than shell weight, thus reducing the correlation between percent kernel and yield. Twenty-seven percent of the trees in the study produced greater than average yields with a lower than average alternate bearing index.

Interaction Between CPPU and NAA on Fruit Thinning and Fruit Development in Selected Apple Cultivars

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 513c-513 ◽  
Author(s):  
Martin J. Bukovac ◽  
Jerome Hull ◽  
John C. Neilsen ◽  
Michael Schroeder ◽  
Georg Noga
Keyword(s):  
Total Yield ◽  
Fruit Size ◽  
Frost Damage ◽  
Fruit Growth ◽  
Soluble Solids ◽  
Seed Number ◽  
Crop Load ◽  
Fruit Thinning ◽  
Carpel Development ◽  
Return Bloom

NAA is used extensively for fruit thinning of apples to increase fruit size and to promote return bloom. In some cultivars, even if thinning is achieved, fruit size at harvest may be less than expected based on crop load. CPPU, N-(2-chloro-4-pyridinyl)-N.-phenylurea, has been shown to increase fruit growth in apples, grapes, and kiwi. We evaluated combinations of NAA and CPPU on thinning, fruit growth and return bloom in Redchief `Delicious', `Elstar', and `Gloster'. CPPU was applied at 5 mgμL–1 (based on 0 to 10 mgμL–1 response curve) in combination with 15 mgμL–1 NAA as high-volume sprays at 7 to 10 mm KFD. Yield and fruit size distribution (on total yield) were used as index of response. In `Delicious', CPPU (3-year study) increased % large (70 mm+) fruit, but in the presence of NAA % large fruit was reduced 2 of the 3 years. CPPU did not induce significant thinning. There were no significant effects on color or soluble solids; firmness was increased slightly and seed number reduced. The L/D ratio was increased and uneven lobe and carpel development was common. CPPU had no significant effect on return bloom in presence or absence of NAA, but NAA increased bloom in both the presence and absence of CPPU. With `Elstar' (2-year study) there was no significant thinning with either chemical, but CPPU increased mean fruit size and % large (70–80 mm) fruit over nonthinned, but not significantly greater than NAA alone. There were no significant differences in firmness, color, soluble solids or seed number. NAA + CPPU did not inhibit fruit growth or cause excessive uneven carpel development. Frost damage reduced crop load in `Gloster' where results were similar to `Elstar' except seed number was reduced by the NAA + CPPU combination.

scholarly journals The Significance of Macronutrients in Alternate Bearing ‘Nadorcott’ Mandarin Trees

HortScience ◽  
2018 ◽  
Vol 53 (11) ◽  
pp. 1600-1609 ◽  
Author(s):  
Ockert P.J. Stander ◽  
Graham H. Barry ◽  
Paul J.R. Cronjé
Keyword(s):  
Treatment Effects ◽  
Foliar Spray ◽  
Shoot Development ◽  
Citrus Reticulata ◽  
Alternate Bearing ◽  
Vegetative Shoot ◽  
Current Season ◽  
Standard Practice ◽  
Main Determinants ◽  
Fruit Load

The significance of macronutrients nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) in leaves was studied in relation with their possible roles in alternate bearing of ‘Nadorcott’ mandarin (Citrus reticulata) trees over a period of three seasons. Fruit load (“on,” a heavy fruit load, vs. “off,” a light fruit load) affected the leaf macronutrient concentrations, and the amount of macronutrients removed through the harvest of fruit, i.e., the crop removal factor (g·kg−1), was consistent in both seasons. The crop removal factors were higher for each macronutrient in “off” trees—harvest of 1 kg fruit removed ≈2.3 g·kg−1 N, 0.3 g·kg−1 P, 3.1 g·kg−1 K, 1.0 g·kg−1 Ca, and 0.4 g·kg−1 Mg, compared with 1.3 g·kg−1 N, 0.2 g·kg−1 P, 1.7 g·kg−1 K, 0.6 g·kg−1 Ca, and 0.2 g·kg−1 Mg in “on” trees. Fruit load per tree (kg/tree) of 84, 110, and 52 kg/tree in “on” trees, however, removed ≈217 g/tree N, 28 g/tree P, 296 g/tree K, 100 g/tree Ca, and 35 g/tree Mg, which was 1.5–6 times more than that of fruit loads of 14, 71, and 16 kg/tree in “off” trees. In “off” trees, N, P, and K, and in “on” trees, Ca accumulated in leaves to between 20% and 30% higher concentrations in season 1, but the higher macronutrient status did not manifest in or consistently correlate with intensity of summer vegetative shoot development in the current season, or intensity of flowering in the next season, the two main determinants of fruit load in ‘Nadorcott’ mandarin. Apart from some anomalies, the concentrations of macronutrients in leaves were unaffected by de-fruiting and foliar spray applications of N and K to “on” trees, and showed no consistent relationship with treatment effects on parameters of vegetative shoot development and flowering. Leaf macronutrients in alternate bearing ‘Nadorcott’ mandarin trees, fertilized according to grower standard practice, are not related to differences in flowering and vegetative shoot development, and appear to be a consequence of fruit load and not a determinant thereof.

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