scholarly journals 684 Thinning and Crop Load Effects on Apple Fruit Growth

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 516E-517
Author(s):  
Duane W. Greene
Keyword(s):  
Growth Rate ◽  
Pollen Germination ◽  
Apple Fruit ◽  
Fruit Growth ◽  
Initial Assessment ◽  
Crop Load ◽  
Specific Chemical ◽  
Load Effects ◽  
Viable Seeds ◽  
June Drop

Chemical thinners can be classified as either blossom thinners or postbloom thinners. Blossom thinners act by inhibit further pollination, pollen germination, or pollen tube growth. At petal fall it is not possible to distinguish between fruit that have been injured by blossom thinners, and those that will persist and continue to grow. The receptacles of blossom thinned fruit do not grow, whereas fruit that has not been treated and that also contain viable seeds, resumes growth within 4 to 6 days, depending upon temperature. Abscission of fruit treated with postbloom thinners does not usually occur until 1.5 to 3 weeks after application. Frequently, it is possible to identify fruit that will abscise and to make an initial assessment of thinning efficacy, within 4 to 6 days following application by measuring fruit growth rate. A reduction in fruit growth by as little as 15% to 20% less than rapidly growing fruit is usually sufficient to assume that the fruit will abscise sometime during the June drop period. The effects of specific chemical thinners on fruit growth and subsequent thinning will be discussed.

scholarly journals Development and Testing of a Model to Rapidly Predict Apple Thinner Response

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 793C-793 ◽  
Author(s):  
D.W. Greene* ◽  
A.N. Lakso ◽  
T.L. Robinson
Keyword(s):  
New York ◽  
Growth Rate ◽  
Fruit Set ◽  
Accurate Method ◽  
Fruit Growth ◽  
Cold Weather ◽  
Accurate Predictor ◽  
Accuracy Of Prediction ◽  
June Drop ◽  
Fruit Diameter

Several thinning experiments were initiated in 2003 to test the hypothesis that monitoring fruit growth is an appropriate and accurate method to predict final fruit set early enough to apply supplemental thinners if appropriate. A total of eight thinning treatments were applied in Massachusetts and New York. On the day of thinner application 70 to 100 spurs were tagged on 4-8 trees (replications). All fruit within a spur were individually identified and fruit were measured. At 2 to 3 day intervals fruit diameter was measured at a designated point on the fruit. Growth rate of the fastest growing 20 fruit on the untreated trees was used as the criteria to determine growth rate of fruit that would persist to harvest. A fruit on a treated tree was predicted to abscise if growth rate slowed to 50% or less of the growth rate of the 20 fastest growing fruit on untreated trees. Cold weather in 2003 following thinner application slowed the response time to thinners. Thinning treatments were applied to Delicious, Golden Delicious, McIntosh, and Gala at 7-9-mm stage. BA, carbaryl, and combinations of NAA and carbaryl were used. In Massachusetts accuracy of prediction of final fruit set at 7-11 days after application ranged from 87% to 100% with and average of 95% accuracy compared to final observed drop at the end of June drop in July. In Geneva, N.Y., the temperature was so unseasonably cold following application that prediction of final set at 7 to 11 days after application was between 68% and 79% with an average of 74% accuracy. We conclude that prediction of final fruit set following growth rate of individual fruit shows promise as an accurate predictor of final fruit set early enough to apply supplemental thinners if appropriate.

Model-assisted evaluation of crop load effects on stem diameter variations and fruit growth in peach

Trees ◽  
2014 ◽  
Vol 28 (6) ◽  
pp. 1607-1622 ◽  
Author(s):  
Tom De Swaef ◽  
Carmen D. Mellisho ◽  
Annelies Baert ◽  
Veerle De Schepper ◽  
Arturo Torrecillas ◽  
...  
Keyword(s):  
Fruit Growth ◽  
Stem Diameter ◽  
Crop Load ◽  
Load Effects ◽  
Stem Diameter Variations

scholarly journals Growth Response of Apple Fruit to NAA and Accel: Effect of Intraspur Competition and Position on a Spur

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 765D-765
Author(s):  
Brent L. Black ◽  
Martin J. Bukovac ◽  
Matej Stopar
Keyword(s):  
Growth Response ◽  
Fruit Size ◽  
Apple Fruit ◽  
Fruit Growth ◽  
Crop Load ◽  
Commercial Thinning ◽  
Whole Tree ◽  
Fruit Diameter

Apple fruit size is influenced by position on the spur, and location and number of competing fruits. King fruit appear to have the greatest potential to size and grow best in the absence of intraspur fruit competition (ISFC). Accel (A) and NAA (N), commercial thinning chemicals, influence fruit size beyond their effects on crop load. A 2-year study was conducted to determine the effect of ISFC and position (king, K, or lateral, L) on fruit growth in response to A and N. Branches from `Redchief Delicious' were thinned, after petal fall, to one K, one L, one K + one L, or two L fruits per spur. Whole-tree treatments of N (15 mg·liter–1), A (50 mg·liter–1, 1993; 25 mg·liter–1), and a combination (N+A) were applied at 10-mm king fruit diameter. A nontreated control was included. In 1993, N and N+A reduced fruit size only with ISFC, while A increased fruit size in the absence of ISFC. In 1994, A had no effect, but N and N+A reduced fruit growth with ISFC. In both seasons, A and N decreased the frequency of spurs bearing multiple fruit, while N+A dramatically increased number of spurs with multiple fruits (branch survey).

Water stress and crop load effects on vegetative and fruit growth of ‘Elegant Lady’ peach [Prunus persica(L.) Batch] trees

Fruits ◽  
2005 ◽  
Vol 60 (1) ◽  
pp. 55-68 ◽  
Author(s):  
Ahmed Mahhou ◽  
Theodore M. DeJong ◽  
Tiesen Cao ◽  
Ken S. Shackel
Keyword(s):  
Water Stress ◽  
Prunus Persica ◽  
Fruit Growth ◽  
Crop Load ◽  
Load Effects

scholarly journals Benzyladenine as A Chemical Thinner for `McIntosh' Apples. II. Effects of Benzyladenine, Bourse Shoot Tip Removal, and Leaf Number on Fruit Retention

2000 ◽  
Vol 125 (2) ◽  
pp. 177-182 ◽  
Author(s):  
Rongcai Yuan ◽  
Duane W. Greene
Keyword(s):  
Growth Rate ◽  
Apple Fruit ◽  
Fruit Weight ◽  
Shoot Tips ◽  
Fruit Growth ◽  
Shoot Tip ◽  
Soluble Solids ◽  
Leaf Number ◽  
Solids Concentration ◽  
Fruiting Branch

Experiments were conducted to evaluate the effects of BA, removal of bourse shoot tips including only folded leaves and growing point, and different numbers of leaves per fruit on fruit retention and fruit development in `More-Spur McIntosh'/Malling 7 (M.7) apple trees [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.]. Removal of the bourse shoot tip increased fruit retention, whereas BA thinned fruit regardless of whether shoot tips were removed or not. There was no interaction between BA application and shoot tipping. BA thinned fruit only when one leaf per fruit was on a girdled small fruiting branch, but not when leaf number per fruit was two or greater. Fruit weight and soluble solids concentration increased dramatically with increasing leaf number per fruit. BA reduced fruit growth rate when <16 leaves per fruit were present on the girdled branches between 3 and 7 days after treatment, but it did not affect fruit growth rate when 32 leaves per fruit were on the girdled branches. Increasing leaf number also increased viable seed number per fruit while decreasing the number of aborted seeds, but it had no effect on the number of total seeds per fruit. BA reduced the number of viable seeds per fruit only when the number of leaves per fruit was less than four. Results suggest that BA thins apple fruit mainly by reducing carbohydrates available to developing fruitlets. Chemical name used: N-(phenylmethyl)-1H-purine-6-amine [benzyladenine (BA)].

scholarly journals Rootstock Effects on Growth and Quality of `Gala' Apples

HortScience ◽  
2004 ◽  
Vol 39 (6) ◽  
pp. 1231-1233 ◽  
Author(s):  
Yahya K. Al-Hinai ◽  
Teryl R. Roper
Keyword(s):  
Agricultural Research ◽  
Fruit Size ◽  
Apple Fruit ◽  
Fruit Weight ◽  
Research Station ◽  
Final Size ◽  
Crop Load ◽  
Yield Efficiency ◽  
Load Effects

The effect of rootstock on apple size is not clear due to inconsistent results of published studies. This study was conducted over 3 years at the Peninsular Agricultural Research Station near Sturgeon Bay, WI on 6-year-old `Gala' apple trees (Malus domestica Borkh) grafted on Malling 26 (M.26), Ottawa 3, M.9 Pajam 1, and Vineland (V)-605 rootstocks. Fruit diameter was measured weekly. Fruit weight and volume were estimated by a quadratic regression of weekly measurements. Fruit weight was positively correlated with fruit volume. Rootstock had no effect on fruit growth and final size even with the removal of crop load effects. Crop load was a highly significant covariate for fruit size, but canopy light interception and seed count were not. Trees on M.26 EMLA had slightly higher yield in 2000 but rootstock did not affect yield efficiency any year. Rootstock had no influence on fruit quality attributes during 2001; however, in 2002, fruit obtained from trees on Pajam-1 tended to be less firm. Generally, apple fruit size was influenced by crop load and other factors, but not by rootstock.

scholarly journals REGULATION OF APPLE FRUIT GROWTH RATE BY TURGOR PRESSURE?

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 625e-625 ◽  
Author(s):  
Douglas D. Archbold
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Osmotic Potential ◽  
Turgor Pressure ◽  
Apple Fruit ◽  
Fruit Growth ◽  
Cultivar Differences ◽  
Soluble Carbohydrates ◽  
Soluble Carbohydrate ◽  
Carbohydrate Levels

Maintenance of positive cell turgor is an essential factor in cell, and fruit, expansion. Since apple fruit partition carbohydrates between the starch and soluble pools to maintain turgor, variation among cultivars in this osmoregulatory aspect may play an important role in defining cultivar-specific fruit growth rates. Cultivar-specific apple fruit growth rates were determined over a 6 week period following June drop during 2 seasons. Fruit water relations parameters and carbohydrate levels were also measured. Although cultivar differences were evident, generally, fruit absolute growth rate increased, relative growth rate (RGR) declined, water potential and osmotic potential declined, and turgor potential increased as the season progressed. Soluble carbohydrate levels increased over 6 weeks, while starch levels fluctuated. Soluble carbohydrates contributed 50 to 90% of the osmotic potential. RGR was not correlated to either turgor potential or the relative allocation of carbohydrates between the soluble and starch pools. Thus, although positive turgor was maintained, factors other than turgor per se determine fruit growth rate.

Reappraisal of seasonal apple fruit growth

1993 ◽  
Vol 73 (2) ◽  
pp. 549-556 ◽  
Author(s):  
I. Schechter ◽  
J. T. A. Proctor ◽  
D. C. Elfving
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Dry Matter ◽  
Dry Weight ◽  
Apple Fruit ◽  
Fruit Growth ◽  
Full Bloom ◽  
Relative Growth ◽  
Dry Matter Concentration ◽  
Matter Concentration

Three apple cultivars (McIntosh, Delicious and Empire) were used in 1989 to study seasonal fruit growth. Fruit fresh weight (FW), dry weight (DW), dry matter concentration (DMC) and relative growth rate (RGR) were regressed against days after full bloom (DAFB) while partitioning the fruit growth curve into either two or three linear phases. Linear phases in fruit DW and FW development were evident throughout most of the growing season. However, cultivars differed in seasonal FW and DW accumulation totals and daily rates. Fruit RGR gradually declined until 75–80 DAFB, when it reached a low and constant rate until harvest. The DMC of fruitlets at about 30–35 DAFB was about half that at full bloom. After an additional 20–30 d during which DMC increased, fruits maintained a relatively stable DMC level to the end of the season. Key words: Malus domestica Borkh., fresh and dry weight, dry matter concentration, relative growth rate

Effect of Seed Number on Preharvest Drop and Fruit Mass of Three Apple Cultivars

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 513d-513
Author(s):  
Daniel L. Ward ◽  
Richard P. Marini ◽  
Ross E. Byers
Keyword(s):  
Apple Fruit ◽  
Appreciable Amount ◽  
Seed Number ◽  
The Third ◽  
Apple Cultivars ◽  
Viable Seeds ◽  
Fruit Mass ◽  
Number Of Seeds ◽  
Filled Seeds ◽  
June Drop

The factors controlling preharvest drop are poorly understood. The number of viable seeds in apple fruit has been associated with fruits retained following June drop. Three experiments were conducted to determine the effect of seed number on time of preharvest drop. In two experiments treatments were imposed to induce variability in seed numbers. Trees of `Redchief Delicious' were covered with 92% shade fabric for 0, 1, 2, or 3 days when fruits averaged 13 mm in diameter. In a second experiment `Redchief Delicious', `Smoothee', and `Commander York' flowers had 0, 1, 2, 3, 4, or all 5 stigmas excised at early “popcorn” stage and the remaining stigmas were hand-pollinated. The third experiment investigated drop of the same three cultivars as affected by the natural variability in seed number. Fruits were gathered from under the trees daily from 26 Aug. until all the fruits had fallen from the trees. Fruits were weighed and the number of filled, large aborted and small aborted seeds were counted. Neither total number of seeds, number of filled seeds, total number of aborted seeds, number of large aborted seeds nor number of small aborted seeds explained any appreciable amount of the variation in date of drop (R2 < 0.13). Fruit mass was positively related to seed number for `Delicious', but not for `Smoothee' or `York'.

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