Fruit thinning affects photosynthetic activity, carbohydrate levels, and shoot and fruit development of olive trees grown under semiarid conditions

2013 ◽  
Vol 40 (11) ◽  
pp. 1179 ◽  
Author(s):  
Afef Haouari ◽  
Marie-Christine Van Labeke ◽  
Kathy Steppe ◽  
Fethi Ben Mariem ◽  
Mohamed Braham ◽  
...  
Keyword(s):  
Fruit Ripening ◽  
Soluble Sugars ◽  
Intercellular Co2 Concentration ◽  
Fruit Size ◽  
Olive Tree ◽  
Carbohydrate Content ◽  
Crop Load ◽  
Chlorophyll Fluorescence Parameters ◽  
Fruit Thinning ◽  
Fruit Load

Olive (Olea europaea L.) production is marked by annual oscillations as trees alternate from high to low crop loads in successive years. Gas exchanges and carbohydrate content of leaves and fruits in olive tree (O. europaea cv. Besbassi) were monitored at pit hardening and fruit ripening. After fruit set, three crop loads were applied (100%, 50% and 25% of the initial fruit load) by manual thinning. Severe fruit thinning reduced photosynthesis, stomatal conductance and intercellular CO2 concentration. Crop load had no significant effect on chlorophyll fluorescence parameters. The reduction of 75% of the initial crop load favoured the accumulation of starch in leaves and soluble sugars in leaves and fruits. The reduction in initial fruit load had a significant positive effect on the current year’s shoot elongation and on inflorescence number the following spring. To increase the fruit size, a strong thinning (75%) was necessary, which coincided with the highest shoot vigour. Moderate thinning (50%) hardly affected leaf carbohydrate content and fruit size, but photosynthetic capacity was only limited at fruit ripening.

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 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.

scholarly journals Predicted Crop Value for Nectarines and Cling Peaches of Different Harvest Season as a Function of Crop Load

HortScience ◽  
2007 ◽  
Vol 42 (2) ◽  
pp. 239-245 ◽  
Author(s):  
Gabino H. Reginato ◽  
Víctor García de Cortázar ◽  
Terence L. Robinson
Keyword(s):  
Size Distribution ◽  
Field Experiments ◽  
Fruit Size ◽  
Tree Size ◽  
Crop Load ◽  
Early Season ◽  
Yield Efficiency ◽  
Late Season ◽  
Wide Range ◽  
Fruit Load

Several field experiments to assess the effect of tree size and crop load on fruit size and yield efficiency were conducted in cling peach and nectarine orchards of different harvest seasons in Chile. Trees were randomly selected in each orchard and then hand-thinned at the beginning of pit hardening to a wide range of crop loads. The fraction of above-canopy photosynthetically active radiation (PAR) intercepted by the canopy (PAR i) was determined at harvest. All fruits were counted and weighed and average fruit weight calculated. Crop load and yield were normalized by tree size measured by intercepted PAR i. For each orchard, the relationship between crop load and fruit size or crop load and yield efficiency was assessed by regression analysis. Fruit size distribution was calculated from fruit size adjusted for fruit load assuming a normal fruit size distribution and valued according to shipment date and price obtained from a Chilean export company. Using crop load as a covariate, fruit size adjusted for crop load was compared for nectarine and peach cultivars. Fruit size adjusted for fruit load and yield efficiency was greater with late season cultivars than the early or midseason cultivars. Predicted crop value (PCV), normalized in terms of PAR intercepted, was calculated for all the cultivars. Large differences in predicted crop value were found for early, midseason, and late ripening nectarines. Early and late ripening cultivars had the highest predicted crop value, especially at lower crop loads and larger fruit sizes. The early season cultivars had high crop value as a result of higher fruit prices, whereas the late season cultivar had high crop value as a result of higher production. With cling peaches, the early season cultivar ‘Jungerman’ had a lower predicted crop value than the late season cultivars ‘Ross’ and ‘Davis’. For cling peaches, the highest PCV was achieved at a relatively high crop load with high yield and small fruit size.

Fruit thinning using NAA shows potential for reducing biennial bearing of 'Barnea' and 'Picual' oil olive trees

2009 ◽  
Vol 60 (12) ◽  
pp. 1124 ◽  
Author(s):  
Arnon Dag ◽  
Amnon Bustan ◽  
Avishai Avni ◽  
Shimon Lavee ◽  
Joseph Riov
Keyword(s):  
Production Systems ◽  
Fruit Size ◽  
Naphthaleneacetic Acid ◽  
Full Bloom ◽  
Biennial Bearing ◽  
Fruit Thinning ◽  
Dynamic Relationship ◽  
Primary Determinant ◽  
Olive Cultivars ◽  
Fruit Load

Biennial bearing is a major horticultural and economic drawback of olive (Olea europaea L.) cultivation, which particularly affects the olive oil industry under intensive production systems. The number of fruits per tree in an on-year is a primary determinant of the biennial cycle. While fruit thinning using NAA shortly after full bloom is commonly practiced to increase fruit size in table olives, the extent of its influence on biennial bearing is unknown. In the present study, the ability of that common naphthaleneacetic acid (NAA) treatment (100 mg/L, 10 days after full bloom) to alleviate biennial bearing in two oil olive cultivars, Picual and Barnea, was poor, although significant influence on the number of fruit was evident solely in Barnea. Picual seemed less susceptible than Barnea to biennial bearing. Consequently, the effect of a broad range of NAA concentrations (0–320 mg/L, 10 days after full bloom) on various yield parameters was investigated during a biennial cycle of Barnea trees. There was a gradual proportional decline in the on-year number of fruits from ~50 000 to 10 000/tree in response to increasing NAA concentrations. The number of return fruits in the off-year was reciprocal to the on-year fruit load, but remained relatively small, below 15 000/tree. The dynamic relationship between fruit load and fruit size in both on- and off-years was a significant compensation factor in fruit and oil yields. In both cultivars, an on-year fruit load smaller than 20 000/tree is likely to provide consistent yearly oil yields ranging from 10 to 12 kg/tree. The results demonstrate the possibility of using NAA post-bloom spraying to balance biennial bearing in oil olives.

scholarly journals Organic fertilization and crop load in yield and quality of organic nectarines in Italy

2021 ◽  
Vol 43 (5) ◽  
Author(s):  
Caroline Farias Barreto ◽  
Luis Eduardo Correa Antunes ◽  
Moreno Toselli ◽  
Elena Baldi ◽  
Giovambattista Sorrenti ◽  
...  
Keyword(s):  
Environmental Sustainability ◽  
Fruit Size ◽  
Fertilization Rate ◽  
Soluble Solids ◽  
Organic Fertilization ◽  
Crop Load ◽  
Po Valley ◽  
Set Up ◽  
Fruit Mass ◽  
Fruit Load

Abstract Organic fertilization in orchards aims at increasing soil fertility, at impacting plant productivity and environmental sustainability. This study aimed at verifying the effects of organic fertilization and fruit load on two nectarine cultivars with high and low fruit loads. The experiment was carried out in an orchard under organic management in Fratta Terme, Po valley, in northeastern Italy. Nectarine cultivars Big Top and Carene, implemented in 2017 and grafted onto GF677, were used. Three levels of compost (0, 20 and 40 t dw ha-1) were combined with two fruit loads (low and high) to set up a factorial experimental design with two factors and four randomized replicates. Compost was incorporated at 20 cm depth. The following parameters were evaluated: nitrate- and ammonium- N concentrations in soil at 20 - 40 cm depth, macro and micronutrients in leaves, tree yield, number of fruits, fruit mass and diameter, soluble solids and pulp firmness. The supply of compost enhanced nitrate-N release in soil. In both cultivars, macro- and micronutrient concentrations in leaves were not affected by organic fertilization or fruit load, except for iron, which increased as a consequence of the compost supply. Low crop load induced higher fruit size in both varieties, a fact that was observed after pit hardening. However, the organic fertilization rate did not influence tree yield, fruit mass and soluble solids.

scholarly journals Crop Load, Fruit Thinning and their Effects on Fruit Quality of Apple (Malus domestica Borkh.)

2006 ◽  
pp. 29-35 ◽  
Author(s):  
József Racskó
Keyword(s):  
Growth Rate ◽  
Fruit Quality ◽  
Fruit Size ◽  
Flower Initiation ◽  
Pome Fruit ◽  
Cross Sectional ◽  
Crop Load ◽  
Fruit Thinning ◽  
Return Bloom ◽  
Tree Leaf

Crop load, a quantitative parameter used by industry, is generally defined as the number of fruit per tree. It is often expressed in terms of number of fruit per trunk cross-sectional area (fruit/TCSA). Crop load is the most important of all factors that influence fruit size, and the removing of a part of the crop is the most effective way to improve fruit size.The potential size of a given pome fruit is determined early in the season and growth proceeds at a relatively uniform rate thereafter. This uniform growth rate permits the accurate prediction of the harvest size of the fruit as early as mid-summer. The growth rate, once established, is not easily altered, and fruit numbers, therefore, can affect fruit size only within definite limits and maximum effectiveness requires adjustment in fruit numbers relatively early in the season. It was established, that „thinning does not change a potentially small fruit into a large fruit, but rather insures that a potentially large fruit will size properly.” Emphasis should be on estimating fruit numbers rather than fruit size.Fruit thinning can quickly reach the point of diminishing returns. Rather than a high percentage of large fruits, the objectives of thinning should be the elimination of the smallest fruits, improved fruit quality and annual production. Fruit thinning is accomplished by hand or chemical thinning. Chemical thinners are separated into categories as bloom thinners and post-bloom thinners. Early removal of potential fruit (blossom thinning) is currently used in many apple producing areas to enhance flower initiation for next year’s crop and thus, return bloom. It also results in reduced competition for photosynthates. Blossom thinners usually have a caustic effect on floral parts.The amount of fruit left on a tree should be determined by the vigor and general condition of the tree. Leaf area per fruit affects the number of spurs flowering the following season. It can be difficult to separate timing and fruit number effects in crop loading studies, as abscission rates after hand thinning of retained flowers/fruitlets tend to very with the time of hand thinning.

scholarly journals Cropping and Fruit Growth in Redchief `Delicious': An Analysis of the Effect of NAA and Cytokinins

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 525A-525
Author(s):  
Martin J. Bukovac ◽  
John C. Neilsen ◽  
Jerome Hull
Keyword(s):  
Fruit Size ◽  
High Volume ◽  
Inhibitory Effect ◽  
Tree Age ◽  
Marked Variation ◽  
Crop Load ◽  
Fruit Thinning ◽  
Single Tree ◽  
Small Fruit ◽  
Effect On Yield

Generally, NAA is effective in inducing fruit thinning in `Delicious'. Although significant thinning may be induced, fruit size at harvest may not be closely related to crop load. Further, the magnitude of response to NAA may vary markedly between seasons. Herein, we present an analysis of response of `Redchief Delicious' over several years (tree age 11–14 years old) to high-volume sprays of NAA (15 mg·L–1), BA (25-50 mg·L–1), and CPPU (5 mg·L–1) at KFD of 8–12 mm. A single tree was used for each treatment replicated four to six times and response was measured by yield and fruit size distribution for each tree. In eight experiments over 4 years, NAA resulted in an average 22% reduction in yield, a 5.1% reduction in large fruit (70 mm+) and 2% reduction in small (<64 mm) fruit compared to NTC. There was a marked variation in response among years. Over 4 years, BA averaged a 5% decrease in yield, a 15% increase in large fruit and a 21% decrease in small fruit. In contrast, when NAA was combined with BA at 25-50 mg·L–1, yield decreased an average of 30%, large fruit decreased by 68%, and small fruit increased 8-fold (2.54 vs 20.6 kg/tree). CPPU alone (2-year study) had no significant effect on yield, but increased large fruit by 60% and significantly reduced production of small fruit. When CPPU was combined with NAA, yield was reduced in both years and the amount of large fruit was increased in 1995, but decreased in 1996. NAA had a very inhibitory effect on fruit size in 1996. One explanation may be that the crop was produced by lateral fruit (king flowers were lost to frost), and NAA has a greater inhibitory effect on lateral than king fruit. Results will be discussed in relation to studies with `Jonathan' and `Empire'.

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 Benzyladenine as A Chemical Thinner for `McIntosh' Apples. I. Fruit Thinning Effect1s and Associated Relationships with Photosynthesis, Assimilate Translocation, and Nonstructural Carbohydrates

2000 ◽  
Vol 125 (2) ◽  
pp. 169-176 ◽  
Author(s):  
Rongcai Yuan ◽  
Duane W. Greene
Keyword(s):  
Dark Respiration ◽  
Soluble Sugars ◽  
Fruit Size ◽  
Net Photosynthesis ◽  
Nonstructural Carbohydrates ◽  
Total Soluble Sugars ◽  
Fruit Abscission ◽  
Fruit Thinning ◽  
Total Nonstructural Carbohydrates ◽  
Carbohydrate Levels

BA was applied at 50 or 100 mg·L-1 to `More-Spur McIntosh'/Malling 7 (M.7) apple trees [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] at the 10 mm stage of fruit development. BA thinned fruit and increased fruit size. There were two distinguishable peaks of fruit abscission during `June drop'. BA accentuated the naturally occurring waves of fruit abscission, and enhanced translocation of 14C-sorbitol from leaves to fruit when applied directly to the fruit, but not when applied directly to the leaves. Net photosynthesis was decreased and dark respiration was increased when temperature following BA application was high (30 °C), whereas there was no effect when temperature was lower (20 °C). Total nonstructural carbohydrates, total soluble sugars, and starch in the leaves decreased dramatically over the 12- or 13-day observation period, regardless of BA treatment. These carbohydrate concentrations in the leaves were lowered further by BA application. Abscising fruit, based on specific reddening of the pedicel, had higher carbohydrate levels than persisting fruit, regardless of BA application. We conclude that BA thins fruit, at least in part, by increasing dark respiration and decreasing net photosynthesis. Chemical name used: N-(phenylmethyl)-1H-purine-6-amine [benzyladenine (BA)].

Bio-regulators improve fruit size and c olour and reduce crop-load and annual bearing of Honeycrisp™ apples

2005 ◽  
Vol 85 (2) ◽  
pp. 453-455
Author(s):  
C. G. Embree ◽  
D. S. Nichols
Keyword(s):  
Fruit Quality ◽  
Malus Domestica ◽  
Fruit Size ◽  
Fruit Weight ◽  
Fruit Colour ◽  
Full Bloom ◽  
Crop Load ◽  
Fruit Thinning ◽  
Colour Category ◽  
Return Bloom

Honeycrisp™ [Malus × domestica (L.) Borkh.] can be a very profitable cultivar if fruit quality is high. Some crop-load bio-regulators were evaluated for improving fruit quality and annual flowering. Ammonium thiosulphate applied at full bloom reduced crop-load, increased fruit weight, fruit colour and return bloom. Fruitone N® combined with Sevin XLR® reduced the percent of fruit in the 40–60% colour category and also crop-load. Fruitone N® alone reduced crop-load. Key words: Honeycrisp™, fruit thinning, crop-load, return bloom

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