Effects Of Exogenous γ- Aminobutyric Acid On Growth,Drought Stress Resistance Of Melon Seedlings In Greenhouse

To solve the problem of melon seedlings growth inhibition and low quality caused by high temperature and drought environment which is common in summer and autumn melon seedling production,this research studied the effect of different concentration of exogenous GABA on growth and drought stress resistance of melon seedlings.The results showed that:1.Exogenous sprayed GABA relieved the growth inhibition of melon seedlings’ shoot and root in drought condition,promoted the content of chlorophyll,leaf area ratio and other growth parameters,improved the expansion of leaves and development of roots.2.Exogenous GABA increased activity of three anti oxygen enzymes including POD,SOD,and CAT,declined the content of MDA,which is harmful to plant cell,decerased the content of Pro and the relative plasmalemma damage degree,which means GABA decreased the level of reactive oxygen stress and osmo stress,helped to protect the structure and function of cell membrane system.3.GABA accumulated in seedling cells markedly under drought stress,and exogenous GABA increased GABA content more,and inhibited the activity of GAD,decreased the synthesis of endogenous GABA,which means exogenous GABA played a role of negative feedback;and exogenous GABA promoted the activity of GABA-T,activated the degradation of GABA.It was also found that the activity of GAD was highly correlated to the cell pH,which means that the lower the cell pH is,the higher the GAD activity is.This research studied the effect and mechanism of GABA promoting the ability against drought stress of melon seedling,and exogenous GABA spraying provides a possible new method to solve the problem of seedling affected by the high temperature and drought condition in summer and autumn melon seedling production.