ALLEVIATION OF WATER STRESS ON SOYBEAN (Glycine max) BY FOLIAR APPLICATION OF POTASSIUM
OMNIA, S. M. HASHEM *
Crop Physiology Research Department, Field Crops Research Institute, A.R.C, Giza, Egypt.
HANIA A. M. ERAKY
Seed Technology Research Section, Field Crops Research Institute, A.R.C, Giza, Egypt.
*Author to whom correspondence should be addressed.
Abstract
An experiment was performed in wiry greenhouse at Giza Experimental Research Station (30.0204508, 31.2067921), ARC, during two summer seasons of 2019 and 2020 to determine the optimum potassium requirement for mitigating the adverse effects of water stress and improving photosynthetic rate, oxidative substance, RWC, growth and seed quality of soybean. Soybean plants were exposed to water stress at different growth stages under water limited regimes,i.e100% (control), 88% (moist), 76% (medium) and 64% (dry) as well as Potassium at the concentrations of 1 and 2% K2O in addition to spraying with water (as control) were applied. Increasing water stress up to 64% significantly decreased chlorophyll fluorescence, RWC, LAI, CGR and yield component, in the contrary, proline, lipid peroxidation and total soluble protein content increased in response to water stress. In water stress treatments, plants treated with 2%K2O showed the highest values for chlorophyll fluorescence (Fv/Fm), RWC, LAI, CGR, protein, carbohydrate, oil, N, P, k seed content, germination measurements and yield component, while proline, lipid peroxidation, total soluble protein content and EC gave the lowest values. It seems that the application of potassium in 2%K2O concentration may improve plant functions in both normal and stress conditions.
Keywords: Water stress, soybean cv, chlorophyll fluorescence, potassium, oxidative substance, seed quality, water relation