THE EFFECT OF DROUGHT STRESS ON GROWTH, PHOTOSYNTHETIC FACTORS, CONTENT OF PROTEIN, Na AND K CONTENT IN TWO CULTIVARS OF SOYBEAN

In this research, the response of shoot and root of two cultivars of soybean (Glycine max L. cvs Gorgan 3 & Williams) to mild and severe drought was evaluated in pot. Two weeks after of planting, three irrigation treatments including every day (as control), once in three (as mild stress) and five days (as severe stress) were used. The results showed that, stem dry weight, stem and root length, internode number and leaf area were not different in mild and severe drought in two cultivars significantly but the amount of soluble sugars decreased in leaf. The content of chlorophylls a & b decreased in mild and severe stress in two cultivars. To increase stress the amount of total protein decreased in root, shoot and nodule and this decrease was more in Williams. K+ content in shoot and Na+ content decreased in roots of two cultivars in comparison to control.