PGPR微胶囊菌剂研发及其对玉米的促生效果评价

Microencapsulated Rhizosphere Bacteria for Promoting Growth of Corn Plants

【目的】为了提高植物根际促生菌(Plant growth-promoting rhizobacteria,PGPR)对作物促生作用的稳定性,研制出以PGPR复合菌液为原料的微胶囊菌剂,探究其对玉米的促生效果。【方法】从玉米根际土壤中分离得到2株PGPR菌株并制备成复合液体菌液。分别用海藻酸钠(SA)和CaCl2作为包埋剂和交联剂,对复合菌液进行包埋以制备微胶囊菌剂。以复合微胶囊菌剂制备的难易程度和菌株包埋率、增殖前活菌数及增殖后活菌数为评价指标,确定微胶囊菌剂制备的最优条件。通过分析微胶囊菌剂在不同聚乙二醇含量、温度、pH、存储时间以及盐含量下的菌株生长及其对玉米生长和根系形态的影响确定PGPR微胶囊菌剂的特性。【结果】分离得到了2株PGPR菌株,具有多种植物促生功能。使用质量分数为1%SA-3%CaCl2制备的微胶囊菌剂稳定性较好,包埋率达91.27%,增殖后的微胶囊活菌数达到8.73×10^(9)cfu·g^(-1),增殖7.79倍。微胶囊菌剂在不同干旱、温度、pH、存储时间和盐浓度条件下对PGPR菌株具有较好的保护作用。PGPR微胶囊菌剂对玉米有显著的促生作用,施用微胶囊菌剂使玉米株高、苗干重和根干重分别增加91.83%、81.82%和29.57%。同时微胶囊菌剂也显著提高了玉米总根长、根表面积、根平均直径、根体积和根尖数。【结论】探明了一种PGPR微胶囊菌剂的制备方法,施用该PGPR微胶囊剂能够显著促进玉米生长、改善玉米根系形态,对玉米的促生效果优于液体菌剂。

【Objective】Microencapsulation was applied to improve the stability of PGPRs for promoting corn growth.【Method】Rhizosphere bacteria that promote corn growth were isolated.The bacteria in broth were encapsulated using sodium alginate(SA)and CaCl2.Based on operation efficiency and PGPR survival rate,optimal conditions for the encapsulation were determined.Properties of the microencapsulated agent were analyzed for field applications with respect to the bacterial proliferation under varied artificial dehydration created by using polyethylene glycol(PEG)and salt,temperatures,pHs,and storage times as well as the growth and root morphology of the treated corn plants.【Result】Two PGPR strains with multiple plant growth promoting functions were isolated.The microcapsule microbial agent prepared with a mass fraction of 1%SA-3%CaCl2 had good stability.The embedding rate of the microcapsule microbial agent reached 91.27%,the number of live bacteria reached 8.73×10^(9)cfu·g^(-1),and the proliferation was 7.79 times.Significant protection against the imposed adverse conditions was observed.In comparison with the virgin PGPRs broth,the encapsulation also significantly enhanced the growth of the treated corn plants with a 91.83%increase on plant height,81.82%on seedling dry weight,and 29.57%on root dry weight over control.In addition,the total length,surface area,diameter,volume,and tip number of the roots of the corn plants grown with the encapsulated PGPRs were significantly increased as well.【Conclusion】Microencapsulation significantly improved the stability as well as the root morphology and growth promoting effect of PGPRs on the corn plants.