Effect Of Exogenous GABA On Germination And Physiological Characteristics Of Melon Seed Under Salinity- Alkalinity Stress

Due to the limitation of the production development, the protected agricultural is easy to produce the environment with salt-alkaline stress. The salt-alkaline stress not only decreased crop yields, affected the quality of crops, but also severely restricted the sustainable and efficient development of crop production. Therefore, to study how to increase crop resistance to salt stress and mechanism have great significance to the high-efficient and high-yield agriculture. γ-aminobutyric acid(GABA) is a kind of non-protein amino acid substance which is widespread in plants and animals. It also could act as the signal substances to indirectly affect the plant growth and development under adversity stress. But there are less researches about exogenous GABA adjusting and improving seed salt resistance mechanism.Two melon(Cucumis melo L.) seeds(‘Yipintianxia 208’, salt sensitive varieties; ‘Jinhui No. 1’, salt-tolerant varieties) were chose as experiment material, the study reached the effect of different concentration of exogenous γ-aminobutyric acid(GABA)((0, 2.5, 5, 10, 50mmol/L) on germination index, eembryo and radicle antioxidant enzyme activity, GABA content and GAD activity of melon seeds under 50mmol/L salinity-alkalinity stress conditions(Na Cl, Na2SO4, Na HCO3, Na2CO3 as molar volume ratio 1:9:9:1).The results showed that salinity-alkalinity stress significantly inhibited the "Yipintianxia 208" melon seed germination rate and germination potential, but it had no effect on "Jinhui No.1" melon’s seed germination rate, germination potential. Salinity-alkalinity stress also significantly inhibited the growth of seeds radicle and embryo. Exogenous GABA pre-soaking treatments have obvious effect on melon seed germination and growth, and have different effects on different melon. Exogenous GABA pre-soaking treatments can improve ‘Yipintianxia 208’ melon seed germination rate and germination potential under salinity-alkalinity stress, but it had no effect on ‘Jinhui No.1’ melon’s seed germination rate and germination potential. Exogenous GABA pre-soaking treatments significantly increased antioxidant enzymes(SOD, POD, CAT) activity and endogenous GABA content, GAD and GABA-T activities, and decreased salinity-alkalinity stress induced inhibition of melon seed germination, and different concentration of GABA seed soaking have different effects, 50 mmol/L GABA was the best one.