ผลร่วมของภาวะร้อนและภาวะแล้งต่อการเติบโต ปริมาณรงควัตถุในการสังเคราะห์ด้วยแสงและการแสดงออกของยีนฮีตช็อคโปรตีนในถั่วเหลือง Glycine max (L.) Merrill
Combined effects of heat and drought conditions on growth, photosynthetic pigment content and heat shock protein gene expression in soybean Glycine max (L.) Merrill
Abstract:
Heat and drought responses in two soybean Glycine max (L.) Merrill cultivars, MK.35 and SJ.5 were investigated. Temperatures at 25, 35 and 40 ํC were used for heat treatment and polyethylene glycol (PEG) 6000 at concentration of 0% and 5% added into nutrient solution were used for drought treatment. The responses were detected on day 0, 3, and 6 after heat and drought stresses and day 3 after returning to normal temperature and rewatering. The results showed that combination of heat and drought treatment in both cultivars increased reduction of relative water content, leaf area, shoot height, root lengthy, fresh and dry weights of shoot and root and photosynthetic pigment content more than each treatment alone while the combination of 5% PEG and temperature at 40 ํC caused the most reduction in all parameters in both cultivars. Comparison of heat and drought combined effects between two cultivars showed that MK.35 showed less decrease in relative water content and growth parameters while SJ. 5 showed less decrease in photosynthetic pigment content. Germination at high temperature increased the germination rate and helped both soybean cultivars to tolerate the combination of heat and drought treatments more than germination at normal temperature. The heat shock protein 70 gene (Hsp70) was induced after 2-4 hours of heat treatment at 40 ํC. High temperature at 40 ํC with additional drought showed lower expression of Hsp70 gene. Based on the data, it was suggested that MK. 35 was more tolerant to combination of heat and drought conditions than SJ.5