EFFECTS OF EXOGENOUS POLY γ-GLUTAMIC ACID ON DROUGHT TOLERANCE AND OSMOTIC ADJUSTMENT OF RICE SEEDLINGS

To explore drought-tolerance improvement effects and its action modes of poly γ-glutamic acid(γ-PGA) on rice seedlings,effects of γ-PGA on growth and osmotic adjustment of hybrid rice Jinyou 38 under polyethylene glycol 6000(PEG-6000) simulated drought stress in a hydroponics culture were investigated.When 100 and 200mg /L exogenous γ-PGA were applied under 12.5% PEG-6000 stress,withering rates of rice seedlings decreased,fresh weight,dry weight and vigor of leaves improved obviously.Furthermore,accumulation of reactive oxygen species were strongly reduced,the contents of organic osmotic substances,such as proline,free amino acids and soluble sugar,increased by 1.3% ～ 8.6%,0.2% ～ 10.7% and 13% ～ 28.6%,respectively,compared with control.Also,the decrease rates in potassium ions were apparently alleviated under drought stress.These indicated that γ-PGA probably improved the drought tolerance of rice seedlings through participation in osmotic adjustment.