Effect of Some Bio-Stimulants on Fruit Drop and Quality of Mango Fruits

Abstract

Current experiment was carried out on two Egyptian traditional mango varieties, "Eiwess and Hendi" to investigate the effect of some natural plant Biostimulants "Kaolin &Chitosan and Jasmine oil" on fruit drop, Fruit storage ability and quality, when applied to young mango trees (5years old) in the preharvest period. The above-cited Biostimulants were sprayed 3 times on healthy mango trees in an orchard adopting recommended agricultural practices. First application was achieved on fruit set stage, the 2nd application one month later, and the 3rd application after another month, during the years of 2018 and 2019. The mango farm is situated in El Sadat district, Monofeya. Immediately after harvest, a sample of 100 mature intact fruits was taken from each treatment and control. Fruits were transported to fruit handling research laboratory for cold storing (13 ± 1°C and RH 85-90%) and estimating fruit quality. The results indicated that treatments caused a pronounced beneficial effect in lowering fruit drop, counted after 2 months of fruit setting, compared to control trees which recorded a percentage of drop between 80% and 94%, in both seasons and always higher than treatments, while jasmine oil treatment resulted in 66% with Eiwess trees and 58% for Hendi trees in first season, followed by chitosan and kaolin, but in second season fruit drop results were mixed with no consistent pattern. Other fruit quality parameters revealed that all treatments induced generally a slower pace of maturity in cold store compared to control. Fruit weight loss percentage of control was higher always compared to treatments fruits, recording in 1st year a range of 4.7% to 6.8%, for Eiwess mango and 4.4% to 6.8 % for Hendi fruits after 2 weeks in cold store, compared to 8.4%-8.6% for control and increased a little bit after 3 weeks and reached a higher level over 10 % after 4 weeks. Second season fruit weight loss was a little bit higher but jasmine oil treatment gave the least weight loss. Fruit firmness of control declined quickly compared to all treatments that had acceptable values till after 2 weeks in cold store (between 3.7-4.8 lb. /in2 for Eiwess, and a range of 4.7-5.8 lb./in2 for Hendi fruits in both seasons) and after 4 weeks fruits were remarkably softer. Fruit freshness, measured by L* values was nearly similar all over the experiment period. The evolution of yellowness of pulp was nearly the same for all treatments and control and after 3 weeks in cold store, it was a little bit quicker for chitosan with Eiwess fruits, (91 degrees) and kaolin for Hendi fruits (91-96 degrees). Values of TSS % increased gradually for all treatments with higher values for control fruits (as it is expected to be more advanced in ripening) and recording about 22% after 3 weeks in cold storage compared to a range of18.7-21% for treatments for Eiwess fruits in both seasons, while values of TSS% of Hendi were smaller and followed the same trend. Control fruits acidity during cold storage had the lowest values compared to treatment fruits whose ac...