Effects And Mechanism Of Application Of Poly-γ-glutamic Acid On Pakchoi

Poly-y-glutamate acid (y-PGA) is a water soluble polyainino acids which have excellent characters such as completely biodegradable, non-toxic to human and environment. y-PGA and its derivates have potential applications in a broad range of industry and agriculture such as food, cosmetics, medicine and manure. Thus this natural and multifunctional biopolymer is worth researching and developing to a commercial material. In this paper, the effect of y-PGA upon the fertilizer efficiency for Pakchoi was studied. And we also studied the ability of y-PGA that to retained nutrients and enhance plant productivity. The main conclusions are following:1) A pot experiment was carried out to study the effects of y-PGA on the growth,yield and quality of Pakchoi. It turned out that the application of y-PGA can obviously improve the cabbage fresh weight production, reduce nitrate content in the leaf blade, and may adjust the plants to Ca, Mg, reasonable distribution of elements, and put in200mg/kg conditions obviously improving the utilization ratio of N cabbage.2) The effect of y-PGA on the Pakchoi in the plot experiment show that y-PGA can significantly improve the fresh weight production, reduce nitrate content, improved chlorophyll content in cabbage, and the best concentration of y-PGA for applying is200mg/L.3) A hydroponic experiment was employed to study the effects of y-PGA addition on the growth of Pakchoi and its photosynthesis characteristics, such as net photosynthesis rate(Pn), stomatic conductance(Gs), intercellular CO2concentration(Ci), and transpiration rate(Tr). The results shows that, as the concentration of nutrient reduces, the level of Pn, Gs, Tr and Ci in Pakchoi leaf treated with y-PGA increases compared with control; in90%nutrient concentration, the application of y-PGA significantly increased chlorophyll a in Pakchoi leaves; in100%-70%nutrient concentration, the above ground yield of cabbage improved compared with control; Treatment with y-PGA can improve root vigor, increase root volume and absorption area. That means y-PGA can promote transformation of light, energy capture, increase the energy efficiency through reducing the stomatal limitation, increasing the chlorophyll content and increasing the capacity of absorption of light intensity. 4) The Hydroponic experiment was concerned on one new plant growth regulators y-PGA on key enzymes of nitrogen metabolism in Pakchoi. The results showed that y-PGA treatment can significantly enhance the activity of nitrate reductase by21.81%on the fourth day, while the results were not detected in the other days. The activity of glutamine synthetase (GS) were increased by9.80%and7.32%respectively on the sixth and eighth day after y-PGA treatment, with a decrease of9.52%on the fourth day. Compared with CK, the activity of protease decreased by30.19%and13.94%respectively on the second and eighth day, but increased by56.47%and29.08%on the fourth and sixth day. After the application of y-PGA in Pakchoi, the contents of ammonium nitrogen of all sampling periods were higher than the CK and the contents of nitrate nitrogen were significantly higher than the CK on the sixth and eighth day.In conclusion, The new plant growth regulator of y-PGA has obvious effect on increasing, and has obvious improvement action on the carbon matter accumulation and nitrogen metabolism of the key enzyme activity in Pakchoi.