Effect of Glycine Betaine and Chitosan on Water Stress Tolerance of Summer Squash Plants.

Two field experiments were conducted at private farm in Belqas, Dakahlia Governorate, Egypt during the two summer seasons of 2020 and 2021 to study the effect of irrigation intervals (7 and 14 days), control (priming and foliar with tap water), glycine betaine seed priming (150 ppm), glycine betaine seed priming (150 ppm) plus glycine betaine foliar application (700 ppm), chitosan seed priming (150 ppm), and chitosan seed priming (150 ppm) plus chitosan foliar application (150 ppm), and their interactions on yield, chemical constituents and quality of summer squash cv Eskandrani. Irrigation intervals every 7days increased significantly yield, total chlorophyll, N, P, K and protein percentages of fruits meanwhile irrigation intervals every 14 days increased significantly phenols, CAT in leaves, VC and carbohydrates in fruits. Glycine betaine or chitosan seed priming with foliar applications had similar effect on most studied characters, which significantly increased in all studied parameters compared with control. The interaction between irrigation every 7 days and chitosan seed priming (at 150 ppm) with foliar application of chitosan (at 150 ppm) recorded the highest values in fruit length, diameter, fruit dry matter, total yield (ton/fed), total chlorophyll, N, P and K and protein percentages in fruits, while phenols, CAT of leaves, VC and carbohydrates in fruits recorded the highest values with the interaction between irrigation every 14 days and glycine betaine seed treatment at 150 ppm with foliar application of glycine betaine (at 700 ppm) compared with other treatments. Therefore, these treatments enhanced the yield under water stress conditions.