The effect of different malch applications and fruit thinning on the quality and yield of the buckeye gala apple cultivar growed under shadow net

In this study, the effects of different mulch materials (black, white, gray color) and fruit thinning applications on fruit yield and quality were investigated. The research was carried out on the 'Buckeye Gala' apple cultivar grafted on the full dwarf apple rootstock (M9) grown in Antalya (Korkuteli district) between 2019-2020. The trees grown in the cord-wire training system are placed under the shade net. In trial trees; in addition to phenological observations (bud rise and burst, beginning of flowering, full bloom and end of flowering), fruit width and length were measured at periodic intervals from fruit set to skin to establish fruit growth curves. On the other hand, yield per tree, pomological (fruit weight, fruit width, flower pit width, fruit volume, fruit firmness, fruit flesh and skin color) and chemical (pH value, SSC, TEA and TFM amount) properties were investigated in fruit samples at optimal harvest maturity. Measurements and analyzes of fruit samples were made at Akdeniz University, Faculty of Agriculture, Department of Horticulture, Physiology and Pomology Laboratories. According to the phenological observation findings; it was determined that there was only a few days difference between mulch applications in both trial years. 3 days difference at the time of flowering (April 12 and April 15) and 4 days difference was determined at the end of flowering (April 25 and April 29) in mulch applications in the 'Buckeye Gala' apple cultivar in 2019 and in the control group respectively. No difference was observed between the mulch applications and the control group in terms of harvest dates (August 21). In 2020, 4 days difference at the start of flowering (April 12 and April 16) and 3 days difference was observed at the end of flowering (April 27 and April 30) in the mulch applications and control group, respectively. In terms of harvest date (August 24), there was no difference between the mulch applications and the control group, as in the first trial year. According to the trial years, the fruit harvest dates are 21 August in 2019; In 2020, it was realized on August 24 with a delay of 3 days. In addition, in the ecological conditions of Antalya (Korkuteli), the width and length development values of the fruits of the 'Buckeye Gala' apple cultivar; It was determined that it increased more slowly from fruit set (May) until the beginning of June and this increase accelerated a little until mid-July, then continued with a decreasing rate until the harvest time (end of August), forming a single (=simple) sigmoid development curve. In the 2019 and 2020 trial years, fruit width values measured at harvest time were higher than fruit length values in thinned and unthinned trees. According to the pomological measurement findings; average fruit weight in all treatments during the trial years;In addition, the highest fruit weight values were obtained from gray (144.01 g) and white (141.93 g) plastic mulch applications on unthinned trees, black (153.59 g) and gray (150.76 g) plastic mulch applications in thinned trees in the trial years. The lowest avg. fruit weight values; were determined from the control groups in both thinned (134.78 g) and unthinned (136.63 g) trees. According to trial years, avg. in fruit length and fruit width; no statistically significant difference was determined between mulch applications on unthinned trees. Average fruit length values were determined higher in thinned trees in all mulch applications (62.48-61.41 mm) than in the control (59.44 mm) group. The mean fruit width values were also higher in the thinning application, in all mulch applications (68.87-67.42 mm), than in the control (65.66 mm) group. The lowest flower pit width was obtained gray color mulch (10.08 mm) in thinned trees and white color mulch (10.17 mm) in unthinned trees in both trial years. Average fruit volume values were determined more in thinned trees (170.87 ml) than in unthinned trees (163.71 ml) in trial years. In addition, for all mulch applications, both unthinned (165.68-164.28 ml) and thinned trees (178.25-173.35 ml) were average fruit volume values were higher than control groups. Mean flesh firmness was higher in thinned trees (7.69 kg/cm2) than unthinned trees (7.50 kg/cm2) in all treatments. Also the lowest average fruit firmness in white (7.32 kg/cm2) and gray (7.45 kg/cm2) plastic mulch applications in unthinned trees and black (7.41 kg/cm2) plastic mulch application on the thinned trees were obtained. According to the chemical analysis findings; the highest average SSC values were obtained from control (13.62%) group and black (12.98%) plastic mulch applications on unthinned trees and control (14.23%) group application on thinned trees in the trial years. Average SSC values were determined higher in thinned trees (13.41%) than in unthinned trees (12.80%) in all treatments in trial years. The highest mean TEA amount was obtained from black mulch application and control (0.34 g/100ml) group on unthinned trees; it was found in the control (0.33 g/100ml) group on thinned trees in two trial years. The average amount of TFM was between 107.32 mg GAE/L (black plastic mulch) and 87.68 mg GAE/L (control group) according to the applications on unthinned trees; it ranged from 114.75 mg GAE/L (control group) to 92.22 mg GAE/L (gray plastic mulch) on thinned trees in trial years. Also the average TFM amount were higher in thinned trees (100.46 mg GAE/L) than unthinned trees (95.24 mg GAE/L) for all applications in the two trial years. In our research findings, it was determined that the weight, volume, width and height measurement values, TFM substance amount and color formation of the fruits grown in the south direction in the thinned trees were higher than the fruits in the north, and this situation positively affected the fruit quality.