scholarly journals Mechanical Crop Load Management (CLM) Improves Fruit Quality and Reduces Fruit Drop and Alternate Bearing in European Plum (Prunus domestica L.)

Horticulturae ◽  
2020 ◽  
Vol 6 (3) ◽  
pp. 52
Author(s):  
Sebastian Lammerich ◽  
Achim Kunz ◽  
Lutz Damerow ◽  
Michael Blanke
Keyword(s):  
Fruit Quality ◽  
Sugar Content ◽  
Fruit Size ◽  
Load Management ◽  
Alternate Bearing ◽  
Crop Load ◽  
Fruit Drop ◽  
Small Fruit ◽  
Class 1 ◽  
Slender Spindle

(1) Background: With ca. 10 million tons of annual production worldwide, the plum (Prunus ssp.) ranks as a major fruit crop and can suffer from small fruit size, premature fruit drop and alternate bearing, which are addressed in this paper using a range of crop load management (CLM) tools. (2) Methods: Sixty 10-year-old European plum cv. “Ortenauer” trees on dwarfing St. Julien INRA GF 655/2 rootstock (slender spindle; 4.25 × 2.80 m) in a commercial orchard near Bonn (50°N), Germany, were thinned in 2 years and flower intensity assessed in the following year. Thinning was performed either mechanically (type Bonn/Baum) or chemically, with ATS (ammonium thiosulfate) or ethephon (Flordimex), or by a combination of mechanical and chemical methods, to improve fruit quality and the proportion of Class 1 fruit. Adjacent un-thinned trees served as controls. (3) Results: Natural fruit drop in June was reduced from 290 fruits per tree in the un-thinned controls to 265 fruits after ATS blossom treatment, and to 148 fruits after mechanical thinning at 380 rpm at a 5 km/h tractor speed at full bloom. The un-thinned control trees developed a large number of small, undersized fruits. The yield of Class 1 fruits increased per tree from 47% in the un-thinned controls, up to 69% after crop load management. Sugar content and fruit firmness were unaffected. (4) Conclusions: The study has shown that fruit quality (i.e., fruit size) and financial returns could be improved by either mechanical (380 rpm at 5 km/h) or chemical thinning, or a combination of both.

Ammonium thiosulfate and 6-benzyladenine improve the crop load and fruit quality of 'Delicious' apples

2007 ◽  
Vol 47 (5) ◽  
pp. 635 ◽  
Author(s):  
S. A. Bound ◽  
S. J. Wilson
Keyword(s):  
Fruit Quality ◽  
Positive Relationship ◽  
Sugar Content ◽  
Fruit Size ◽  
Fruit Weight ◽  
Fruit Firmness ◽  
Single Application ◽  
Crop Load ◽  
Ammonium Thiosulfate

Four trials were conducted over 3 years to assess the effect of ammonium thiosulfate (ATS) as a blossom thinner of ‘Delicious’ apple trees. In addition to determining the optimal concentration of ATS and the effectiveness of multiple applications, the effect on fruit quality was assessed. A program using ATS at bloom and 6-benzyladenine (BA) applied postbloom was examined. Multiple applications of ATS reduced crop load more than a single application. A concentration of 1.0% (v/v, 5800 mg/L) applied twice during the flowering period is recommended, with the first application at 20% bloom and the second at 80% bloom. Fruit firmness and sugar content were increased by ATS, and a positive relationship between fruit weight and sugar content and between fruit weight and firmness was demonstrated. ATS can also be effectively combined in a program with BA with the added benefits of increases in fruit size, firmness and sugar content; however, caution is advised to prevent over-thinning.

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.

scholarly journals Optimizing Fruit-Thinning Strategies in Peach (Prunus persica) Production

Horticulturae ◽  
2020 ◽  
Vol 6 (3) ◽  
pp. 41 ◽  
Author(s):  
Mary Sutton ◽  
John Doyle ◽  
Dario Chavez ◽  
Anish Malladi
Keyword(s):  
Fruit Development ◽  
Fruit Size ◽  
Fruit Weight ◽  
Load Management ◽  
Growth Responses ◽  
Crop Load ◽  
Fruit Number ◽  
Fruit Thinning ◽  
Adverse Weather ◽  
One Year

Fruit size is a highly valued commercial trait in peach. Competition among fruit and among other sinks on a tree reduces potential growth rate of the fruit. Hence, crop-load management strategies such as thinning (removal of flowers or fruit) are often practiced by growers to optimize fruit size. Thinning can be performed at bloom or during early fruit development and at different intensities to optimize fruit growth responses. Responses to thinning may be cultivar and location specific. The objective of the current study was to fine-tune thinning strategies in the southeastern United States, a major peach producing region. Timing and intensity of thinning were evaluated across multiple cultivars over three years. Thinning at bloom or at 21 d after full bloom (DAFB) improved fruit size in comparison to unthinned trees in ‘Cary Mac’ and ‘July Prince’, respectively, in one year. Bloom-thinning reduced fruit yield (kg per tree) in the above cultivars in one year, suggesting that flower thinning alone may not be a viable option in this region. Intensity of thinning, evaluated as spacings of 15 cm and 20 cm between fruit, did not differentially affect fruit weight or yield. However, fruit diameter decreased quadratically with increasing fruit number per tree in ‘Cary Mac’, ‘July Prince’ and ‘Summer Flame’. Similarly, fruit weight decreased quadratically in response to increase in fruit number per tree in ‘Cary Mac’ and ‘July Prince’. Further, yield-per-tree decreased with increasing fruit size in ‘Cary Mac’ and ‘July Prince’. Importantly, these relationships were cultivar specific. Together, the data suggest that achieving a target fruit number per tree is an effective strategy for crop-load management to optimize fruit size in southeastern peach production. The target fruit number per tree may potentially be achieved through a combination of flower and fruit-thinning during early fruit development. Such an approach may provide flexibility in crop-load management in relation to adverse weather events.

Improving fruit size and packout of Late Valencia oranges with ethephon fruit-thinning sprays

1992 ◽  
Vol 32 (6) ◽  
pp. 753 ◽  
Author(s):  
RJ Hutton
Keyword(s):  
Fruit Quality ◽  
Fruit Size ◽  
High Volume ◽  
Cropping Pattern ◽  
Alternate Bearing ◽  
Fruit Thinning ◽  
Unaffected Control ◽  
Marketable Fruit ◽  
Orange Trees ◽  
Spray Treatment

This study set out to establish concentrations of ethephon sprays that could reliably thin alternate cropping orange trees in a heavy set year to improve fruit quality for fresh marketing. An optimum concentration of ethephon as a thinning agent was identified for the practical control of alternate cropping in Late Valencia oranges. A single, high volume spray of ethephon (as Ethrel, 42-60 mL/100 L water), applied in a heavy-set year at 6-8 weeks post bloom when fruitlet size was 10-15 mm diameter, induced a 15-20% reduction in fruit number. This resulted in significantly improved fruit size and marketable outturn with negligible yield penalty. In the 2 successive harvests following spray treatment, the cropping pattern remained uniform and a 14% improvement in packout (marketable fruit size <100 counts per carton) was maintained. Internal fruit quality was unaffected. Control of alternate bearing was carried forward for at least 2 seasons with relatively stable yields following a single spray treatment.

INFLUENCES OF LATENT VIRUSES ON VIGOR, YIELD AND QUALITY OF BRITISH SOVEREIGN STRAWBERRIES

1962 ◽  
Vol 42 (4) ◽  
pp. 602-610 ◽  
Author(s):  
Jack A. Freeman ◽  
Frances C. Mellor
Keyword(s):  
Virus Infection ◽  
Fruit Quality ◽  
Sugar Content ◽  
Fruit Size ◽  
Reduce Sugar Content ◽  
Total Acid ◽  
Yield And Quality ◽  
Reduce Sugar ◽  
The Hill

Comparison of the effect of two strains of mottle virus, two strains of veinbanding virus, and latent-A virus, alone and in combination, on vigor, yield and quality of British Sovereign strawberry plants grown under two planting systems showed: 1. Vigor was reduced by infection by a single virus and still further reduced by two viruses; 2. Yield was reduced by virus infection, especially during the first fruiting year when plants were grown under the hill system; 3. Fruit size was reduced only by virus combinations; 4. Fruit quality was affected only by veinbanding, which increased the total acid content and tended to reduce sugar content.

scholarly journals Effect of gibberellic acid and urea on the growth of pineapple fruit (Ananas comosus (L.) Merr.)

2019 ◽  
Vol 3 (2) ◽  
pp. 82-89
Author(s):  
Le Van Ut ◽  
Vo Thi Bach Mai
Keyword(s):  
Gibberellic Acid ◽  
Fruit Quality ◽  
Quality Index ◽  
Sugar Content ◽  
Fruit Size ◽  
Growth Period ◽  
Fruit Weight ◽  
Ananas Comosus ◽  
High Concentration ◽  
Pineapple Fruit

Effects of gibberellic acid (GA3) and urea on Queen pineapples (Ananas comosus (L.) Merr.) growth in the field were discussed in this study. Pineapples were sprayed with GA3 (at the concentration of 1, 5, 10, 20, 40, 60, 80 and 100 mg.L-1) or urea (at the concentration of 1, 5, 10, 15, 20, 25 and 30 g.L-1) on day 0 and day 3 at the beginning of growth period (50% dried flowers). Fruits were sampled every 15 days from day 0 to day 75 for assessment on fruit weight, fruit size, and fruit quality. Besides, fruits (which were sprayed with GA3 at the concentration of 40 mg.L-1 or urea at the concentration of 15 g.L-1) were sampled on the 15th day from the day which processed to determine the size of cells. The results showed that the treatments with four highest concentration of GA3 (40, 60, 80 and 100 mg.L-1) or urea (15, 20, 25 and 30 g.L-1) significantly increased fruit weights and fruit sizes. In addition, the treatments of GA3 in high concentration (40 - 100 mg.L-1) stimulated the increase of sugar content and vitamin C content in the fruit flesh compared to the control. The treatments of urea at different concentrations did not alter the fruit quality index. Exogenous GA3 at the concentration of 40 mg.L-1 or urea at the concentration of 15 g.L-1 stimulated the increase of fruit weight without decreasing the fruit quality. In which, exogenous GA3 at concentration 40 mg.L-1 increased the fruit weight by enlarging flesh cell.  

scholarly journals Crop Load Influences Fruit Quality, Nutritional Balance, and Return Bloom in ‘Honeycrisp’ Apple

HortScience ◽  
2016 ◽  
Vol 51 (3) ◽  
pp. 236-244 ◽  
Author(s):  
Sara Serra ◽  
Rachel Leisso ◽  
Luca Giordani ◽  
Lee Kalcsits ◽  
Stefano Musacchi
Keyword(s):  
Fruit Quality ◽  
Dry Matter ◽  
Fruit Size ◽  
Soluble Solids ◽  
Postharvest Quality ◽  
Soluble Solid Content ◽  
Crop Load ◽  
Apple Variety ◽  
Return Bloom ◽  
The Impact

The apple variety, ‘Honeycrisp’ has been extensively planted in North America during the last two decades. However, it suffers from several agronomic problems that limit productivity and postharvest quality. To reduce losses, new information is needed to better describe the impact of crop load on productivity and postharvest fruit quality in a desert environment and the major region where ‘Honeycrisp’ expansion is occurring. Here, 7-year-old ‘Honeycrisp’ trees on the M9-Nic29 rootstock (2.5 × 0.9 m) were hand thinned to five different crop loads [from 4.7 to 16.0 fruit/cm2 of trunk cross-sectional area (TCSA)] to compare fruit quality, maturity, fruit size, elemental concentration, and return bloom. Fruit size distribution was affected by crop load. Trees with the highest crop load (16 fruit/cm2) produced smaller fruit. Index of absorbance difference (IAD) measurements (absorption difference between 670 and 720 nm), a proxy indicator of the chlorophyll content below the skin of fruit measured by a DA-meter, were made shortly after harvest (T0) and after 6 months of storage (T1). Fruit from the trees with the lowest crop load had lower IAD values indicating advanced fruit ripeness. The comparison between the IAD classes at T0 and T1 showed that fruit belonging to the lowest IAD class had significantly higher red-blushed overcolor percentage, firmness, dry matter, and soluble solid content than those in the “most unripe” class (highest IAD readings) regardless of crop load. The percentage of blushed color, firmness, titratable acidity (TA), soluble solids content, and dry matter were all higher in the lowest crop loads at both T0 and T1. Fruit calcium (Ca) concentration was lowest at the lowest crop load. The (K + Mg + N):Ca ratio decreased as crop load increased until a crop load of 11.3 fruit/cm2, which was not significantly different from higher crop loads. For return bloom, the highest number of flower clusters per tree was reported for 4.7 fruit/cm2 crop load, and generally it decreased as crop load increased. Here, we highlight the corresponding changes in fruit quality, storability, and elemental balance with tree crop load. To maintain high fruit quality and consistency in yield, careful crop load management is required to minimize bienniality and improve fruit quality and storability.

scholarly journals Influences of girdling and potassium treatments on fruit quality and some physiological characters of ‘Fremont’ mandarin variety

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Tuğba Ülker ◽  
Müge Uysal Kamiloğlu
Keyword(s):  
Fruit Quality ◽  
Sugar Content ◽  
Chlorophyll Concentration ◽  
Fruit Size ◽  
Potassium Nitrate ◽  
Leaf Nitrogen ◽  
Fruit Yield ◽  
Leaf Nitrogen Content ◽  
Total Sugar Content ◽  
N Concentration

Abstract Growing citrus involves cultural treatments such as girdling and foliar potassium treatment to increase fruit size, yield and quality. The aim of the study was to evaluate the effects of single and double stem girdling, potassium nitrate (KNO3) treatment on leaves and combinations of these treatments on the fruit yield, size and quality characteristics, leaf chlorophyll concentration and leaf nitrogen content, leaf fluorescence (PSII) and leaf sugar content of the ‘Fremont’ mandarin variety. Girdling treatments were applied on the stem by removing 4 mm wide ring of bark at the end of anthesis and after the June fruit drop. Foliar KNO3 applications were applied at a concentration of 4% twice (90 days and 120 days after full anthesis) in the experiment. The single girdling (SG) and double girdling (DG) treatments on stems increased fruit yield (kg · tree−1) by approximately 40% relative to the control (C). Treatments did not significantly affect the internal fruit quality of the ‘Fremont’ mandarin variety except in fruit colour and appearance. The highest impact on fruit size was found in the DG + KNO3 treatment. According to treatments and periods, the SPAD values varied between 62.08 and 70.67, whereas the PSII values varied between 0.698 and 0.756. The treatments significantly increased the leaf nitrogen (N) concentration and the fructose, glucose and sucrose concentrations relative to the control. The highest N concentration content was detected in the foliar potassium treatment, and the highest total sugar content was detected in the SG treatment.

scholarly journals (463) Grapefruit Crop Load Affects Net Gas Exchange of Leaves, Tree Growth, and Fruit Quality

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1048A-1048
Author(s):  
Kuo-Tan Li ◽  
Jim Syvertsen ◽  
Jill Dunlop
Keyword(s):  
Fruit Quality ◽  
Fruit Size ◽  
Dry Weight ◽  
Fruit Shape ◽  
Solid Content ◽  
Soluble Solid Content ◽  
Citrus Paradisi ◽  
Fruit Removal ◽  
Crop Load ◽  
Four Levels

Effects of crop load on leaf characteristics, shoot growth, fruit shape, fruit quality, and return bloom were investigated in 13-year-old `Ruby Red' grapefruit (Citrus paradisi Macf.) on `Swingle' citrumleo rootstock. Trees were hand thinned in June 2003 and 2004 at the end of physiological fruit drop to establish three to four levels of crop load ranging from normal (high crop load without thinning) to extremely low (near 90% fruit removal). Leaves on high crop load trees had higher net assimilation of CO2 (ACO2) than those on low crop load trees. Crop load enhancement of ACO2 continued until harvest. In 2004, however, the effects were diminished in October just prior to the beginning of the harvest season, after leaf and fruit loss from three consecutive hurricanes. There was no difference in leaf dry weight per leaf area and leaf nitrogen among treatments. Nonfruiting branches of high crop load trees produced fewer, but longer, summer flushes than those of low crop load trees. Fruiting branches generally produced few summer flushes with similar shoot lengths among treatments. High crop load trees developed a greater percentage of vegetative shoots, whereas low crop load trees developed more inflorescences. Crop load adjustments did not affect fruit size and total soluble solid content, but low crop load trees produced a higher percentage of irregular shape (sheepnosed) fruit with high acidity.

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