Regulation of source: sink relationship, fruit set, fruit growth and fruit quality in European plum (Prunus domestica L.)—using thinning for crop load management

2011 ◽  
Vol 65 (2) ◽  
pp. 335-341 ◽  
Author(s):  
Claudia Seehuber ◽  
Lutz Damerow ◽  
Michael Blanke
Keyword(s):  
Fruit Quality ◽  
Fruit Set ◽  
Fruit Growth ◽  
Load Management ◽  
Prunus Domestica ◽  
Crop Load ◽  
Source Sink

Effects of the bioregulators ACC, 6-BA, ABA, and NAA as thinning agents on Gala apples

2020 ◽  
Vol 100 (2) ◽  
pp. 185-201 ◽  
Author(s):  
Michelle H. Cortens ◽  
John A. Cline
Keyword(s):  
Abscisic Acid ◽  
Fruit Quality ◽  
Fruit Set ◽  
Load Management ◽  
Environmental Concerns ◽  
Naphthaleneacetic Acid ◽  
Management Options ◽  
Crop Load ◽  
Southern Ontario ◽  
Malus Domestica Borkh

Gala apple (Malus domestica Borkh.) trees are prone to heavy cropping but respond to chemical fruitlet thinners to reduce crop load and improve fruit quality. Environmental concerns over the fate of the chemical fruitlet thinner carbaryl is widely acknowledged, but crop load management options are limited. In southern Ontario, Gala trees were treated with new thinning compounds or combinations to determine post-bloom thinning efficacy and resulting fruit quality. Treatments included 6-benzyladenine (6-BA) combined with naphthaleneacetic acid (NAA) or abscisic acid (ABA), and 1-aminocyclopropane-1-carboxylic acid (ACC) alone applied at 9 mm in 2014 and 17 mm in 2015. The treatment NAA + 6-BA produced unacceptably small “pygmy” fruit when applied at 17 mm fruitlet diameter. ABA at 150 and 300 mg L−1 and ACC at 150 mg L−1, when applied at 17 mm fruitlet diameter, resulted in acceptable fruit set, crop load, and quality results in comparison with the carbaryl thinner in 1 yr. The bioregulators ACC and ABA combined with 6-BA showed commercial potential for thinning Gala fruit but require further evaluation.

Mechanical blossom thinning of apples and influence on yield, fruit quality and spur leaf area

2015 ◽  
Vol 95 (5) ◽  
pp. 887-896 ◽  
Author(s):  
Kendra A. McClure ◽  
John A. Cline
Keyword(s):  
Leaf Area ◽  
Fruit Quality ◽  
Fruit Set ◽  
Quality Parameters ◽  
Load Management ◽  
Crop Load ◽  
Yield And Quality ◽  
Mechanical Removal ◽  
New Crop

McClure, K. A. and Cline, J. A. 2015. Mechanical blossom thinning of apples and influence on yield, fruit quality and spur leaf area. Can. J. Plant Sci. 95: 887–896. Apple (Malus×domestica Borkh.) trees tend to crop heavily, which often makes crop load adjustment necessary. This can now be achieved as early as bloom by mechanical removal/thinning of blossoms. High-density Empire/M.26 and Royal Gala/M.26 apple trees were mechanically (MBT) and hand blossom thinned (HBT) in 2010 and 2011, respectively, and their effects on fruit set, subsequent hand thinning, final crop load, and spur leaf area were measured. In both years, MBT effectively thinned trees and reduced fruit set, but did not reduce the requirement for follow-up hand fruitlet thinning after June drop in 2011. In 2010, harvest yields for MBT treatments decreased, while weight and diameter increased. In 2011, most harvest and fruit quality parameters were unaffected by thinning. Trees that were mechanically thinned had significantly reduced spur leaf area, but were similar to unthinned control trees with respect to many of the yield and quality parameters measured. Mechanical blossom thinning is a new crop load management option for apple growers looking to supplement more traditional chemical and hand thinning techniques.

scholarly journals Crop Load Management Does Not Consistently Improve Crop Value of ‘Sweetheart’/‘Mazzard’ Sweet Cherry Trees

2011 ◽  
Vol 21 (5) ◽  
pp. 546-553 ◽  
Author(s):  
Todd C. Einhorn ◽  
Debra Laraway ◽  
Janet Turner
Keyword(s):  
Fruit Quality ◽  
Sweet Cherry ◽  
Load Level ◽  
Fruit Growth ◽  
Soluble Solids ◽  
Load Management ◽  
Fresh Market ◽  
Crop Load ◽  
Tree Crop ◽  
Return Bloom

The effect of crop load level on vegetative growth, fruit growth, yield, fruit quality, surface pitting, crop value and return bloom was studied over a 2-year period on 9- and 10-year-old ‘Sweetheart’/‘Mazzard’ sweet cherry (Prunus avium) trees. In early spring, whole-tree crop loads were adjusted to two different levels by removal of reproductive buds (either 50% or all but one) from spurs and compared with an unthinned control. In 2009, heavy crop loads of unthinned trees reduced fruit size by 30 days after full bloom (DAFB). At harvest, fruit diameter of thinned treatments was increased 22% and 27% compared with unthinned fruit. Fruit quality attributes [soluble solids concentration (SS), fruit firmness, and total acids (TA)] were significantly greater for thinned treatments. Thinned treatment yields were reduced 40% to 54% relative to unthinned trees, with greater percentages of fruit in large size classes. Despite significantly fewer fruit per tree, moderately thinned trees had a higher estimated crop value ($142 per tree) than unthinned trees ($125 per tree). Crop value was lowest for the heavily thinned treatment ($107 per tree), reflecting overthinning. In 2010, shoot growth was negatively related to crop load level. Fruit growth of unthinned trees was not significantly affected by higher fruit density until 89 DAFB. Yield of 2010 unthinned trees was 87% of 2009, while thinned tree yields were similar between years. Improved fruit quality and greater percentages of large fruit were observed for thinned treatments in 2010; however, crop value was highest for unthinned trees ($190 per tree), even though 18% of the fruit were too small for fresh market sale. Surface pitting was unaffected by crop load level in either year. Return bloom (flowers per reproductive bud and reproductive buds per spur) was significantly, negatively related to the prior season's crop load in 2010 and 2011. In the current sweet cherry pricing structure, higher crop value is associated with large volumes of medium-sized fruit. Thinning to manage crop load of low-medium density, productive ‘Sweetheart’/‘Mazzard’ trees will not be an annual requirement, though in heavy fruit set years crop load management will improve crop value.

scholarly journals Mechanical Fruit Thinning Influences Fruit Quality, Yield, Return Fruit Set, and Cold Injury of Pecan

HortScience ◽  
1993 ◽  
Vol 28 (11) ◽  
pp. 1081-1084 ◽  
Author(s):  
Michael W. Smith ◽  
William Reid ◽  
Becky Carroll ◽  
Becky Cheary
Keyword(s):  
Fruit Quality ◽  
Fruit Set ◽  
Temperature Drop ◽  
Carya Illinoinensis ◽  
Canopy Height ◽  
Cold Injury ◽  
Crop Load ◽  
Fruit Thinning

Pecan [Carya illinoinensis (Wangenh.) C. Koch] fruit were thinned from `Mohawk' trees in Oklahoma and `Giles' trees in Kansas with a mechanical trunk shaker. All trees bore an excessive crop load before shaking. Fruit thinning improved the kernel percentage, individual nut weight, and kernel grade of `Mohawk', but nut characteristics of `Giles' were not affected by fruit thinning. Cold injury, caused by a sudden temperature drop in November, was positively related to the percentage of fruiting shoots in both cultivars. Fruit set in 1992 was negatively related to the percentage of fruiting shoots in 1991 in both cultivars. Consistent annual fruit set could be induced in `Giles' by fruit thinning, but return fruit set in `Mohawk', even at high levels of thinning, was low. Fruit thinning reduced yield the year of thinning in both cultivars. Thus, `Mohawk' trees should be thinned so that 50% to 60% of shoots bearing fruit at mid-canopy height would remain, and `Giles' trees should be thinned similarly to 65% to 70%.

scholarly journals Synthetic Cytokinin-1-(2=chloro=4=pyridyl)-3-phenylurea (CPPU)-Promotes Fruit Set and Induces Parthenocarpy in Watermelon

1995 ◽  
Vol 120 (6) ◽  
pp. 997-1000 ◽  
Author(s):  
Yasuyoshi Hayata ◽  
Yoshiyuki Niimi ◽  
Naoto Iwasaki
Keyword(s):  
Fruit Quality ◽  
Fruit Set ◽  
Fruit Growth ◽  
Soluble Solids ◽  
Parthenocarpic Fruit ◽  
Soluble Solids Content ◽  
Control Fruit ◽  
Seedless Fruit ◽  
Solids Content

Applying a 200 ppm solution of CPPU to pollinated ovaries of watermelon (Citrullus lunatus Matsum) at anthesis increased fruit set from 26.9% (control) to 95%. Applying CPPU solutions to nonpollinated ovaries at anthesis induced parthenocarpy, yielding 65% and 89.5% fruit set, respectively with 20 and 200 ppm applications. However, 64% of the 20 ppm CPPU-treated parthenocarpic fruit stopped growth 10 days after treatment. Growth of CPPU-treated, pollinated, and nonpollinated fruit increased significantly compared with growth of control fruit during the first 10 days after treatment, but, except for the 20 ppm CPPU parthenocarpic fruit, growth subsequently slowed, resulting in fruit equal in size to the control by harvest. CPPU application did not affect soluble solids content of pollinated fruit, but reduced content of parthenocarpic fruit treated with 20 ppm. Fructose content was generally higher than glucose and sucrose at harvest. However, in pollinated fruit treated with 20 ppm CPPU, sucrose levels were higher than glucose and fructose. These results suggest that CPPU is practical for promoting fruit set and seedless fruit without adversely affecting fruit quality and development.

scholarly journals Blossom Thinners Reduce Crop Load and Increase Fruit Size and Quality of Peaches

HortScience ◽  
2006 ◽  
Vol 41 (5) ◽  
pp. 1253-1258 ◽  
Author(s):  
Elina D. Coneva ◽  
John A. Cline
Keyword(s):  
Fruit Quality ◽  
Fruit Set ◽  
Fruit Size ◽  
Full Bloom ◽  
Phenological Stages ◽  
Crop Load ◽  
Crop Density ◽  
Peach Trees ◽  
Spray Gun

The purpose of this research was to determine the effectiveness of three blossom-thinning compounds on crop density and fruit quality of two peach cultivars. Treatments consisted of 15 ml·L–1 and 30 ml·L–1 ammonium thiosulphate, 30 ml·L–1 and 40 ml·L–1 decyl alcohol, and 40 ml·L–1 lime sulfur. Treatments were applied to `Redhaven' and `Harrow Diamond' peach trees at two phenological stages: 80%, and 100% full bloom in 2002 and 2003. In both years, treatments reduced the crop density in both cultivars, and in 2003 the amount of hand thinning required to adjust the crop load was significantly reduced. Fruit size from several blossom-thinned treatments was comparable with that observed from hand-thinned trees. However, treatments caused significant leaf phytotoxicity to `Harrow Diamond' trees in 2003, likely a result of hand spray gun applications. These data indicate that chemical sprays at bloom can be used successfully to reduce fruit set, but are very environmentally, dose, and cultivar dependent.

scholarly journals Comparison of Chemical Blossom Thinners Using ‘Golden Delicious’ and ‘Gala’ Pollen Tube Growth Models as Timing Aids

HortScience ◽  
2018 ◽  
Vol 53 (8) ◽  
pp. 1143-1151
Author(s):  
Thomas M. Kon ◽  
James R. Schupp ◽  
Keith S. Yoder ◽  
Leon D. Combs ◽  
Melanie A. Schupp
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Fruit Set ◽  
Fruit Size ◽  
Pollen Tubes ◽  
Tube Growth ◽  
Load Management ◽  
Crop Load ◽  
Crop Density ◽  
Golden Delicious

Reducing apple crop load during bloom can increase fruit size and promote annual bearing when compared with crop reduction at later timings. In this study, we compared the efficacy of chemical blossom-thinning strategies on ‘Golden Delicious’ and ‘Gala’ apple trees. Several blossom-thinning treatments were evaluated, including 1) unthinned control (control), 2) hand-thinned (HT) at bloom, 3) liquid lime sulfur + Stylet-Oil (LS + SO), 4) ammonium thiosulfate (ATS), 5) endothall (ET), and 6) naphthaleneacetamide (NAD). Chemical treatments were applied twice during bloom, using a predictive model to determine application timings. Blossom thinner effects on pollen tube growth, fruit set, and yield responses were evaluated. LS + SO and ATS reduced the number of pollen tubes that entered the style for ‘Golden Delicious’ by 75% and 63%, respectively. ET and NAD did not affect the number of pollen tubes that entered the style. In one of 2 years, LS + SO resulted in a near-ideal crop load and increased fruit weight. ATS was effective in reducing initial fruit set in ‘Golden Delicious’ and ‘Gala’, but did not reduce whole-tree crop density. ET reduced crop load in all experiments but caused excessive spur leaf injury and negatively affected fruit size of ‘Gala’ but not ‘Golden Delicious’. NAD had limited efficacy on ‘Golden Delicious’ at the concentrations and application timings used in this trial. When used as the sole method of crop load management, none of the chemistries evaluated over-thinned or increased fruit injury. However, ET caused excessive thinning when evaluated as part of a commercial crop load management program on ‘Gala’. Of the products evaluated, LS + SO provided the best overall thinning response.

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