Chilling tolerance of maize (Zea mays L.) can be improved by seed soaking in putrescine

Response surface analysis (RSA) experiment with two factors (putrescine (Put) concentration and seed soaking time) of 14 combinations was performed to investigate the effects on improving seed vigor under chilling stress in maize (Zea mays L.) cv. Mo17 (chilling-sensitive). After soaking treatment, treated seeds were germinated suffering low temperature stress at 5 degrees C for three days. Then, the (try weight, relative growth rate and relative electrolyte leakage of roots and shoots were analyzed by RSA. The optimum combinations of Put concentration and soaking time for increasing shoot dry weight (SDW), root dry weight (RDW), shoot relative growth rate (SRGR) and decreasing shoot relative electrolyte leakage (SREL) were obtained. According to these optimum combinations, the optimum ranges for Put soaking concentration and soaking time were 0.45-0.60 mM and 11.5-17.9 h, respectively. It suggests that seed soaking in putrescine can improve chilling tolerance of maize seeds.