RERFORMANCE OF PLANT GROWTH PROMOTING RHIZOBACTERIA CONTAINING ACC-DEAMINASE ACTIVITY FOR IMPROVING GROWTH OF MAIZE UNDER SAL T-STRESSED CONDITIONS

摘要

Bacteria carrying 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity lower stress induced ethyienelevels and may be effective to improve plant growth under salt stress conditions. Twenty strains of rhizobacteriaisolated from soil samples taken from different salt affected aras were screened for plant growth promotion andACC- deaminase enzyme activity under axenic conditions at 6 dS rrf1. Three strains (S5, S15 and S20) thatpromoted growth to the greatest extent under axenic conditions were selected for further study in pot trial at 0, 5,10 dS m~(-1). Results of pot trial showed that the increase in salinity level decreased the growth of the maizeseedlings. However, inoculation of maize seeds with these three rhizobacterial strains performed well at allsalinity levels, and the strain S20 at 5 dS m~(-1) significantly increased root/shoot length, root fresh/dry weight andshoot fresh/dry weight up to 56/62, 51/71, 52/61%, respectively, over uninoculated control. At 10 dS m~(-1) increasewas 120/63, 52/71, 59/118%, respectively, over uninoculated control. Similarly, increase in chlorophyll a, b andcarotenoid contents of fresh leaves increased up to 86% at 5 dS m~(-1) and up to 84% at 10 dS m~(-1) by strain S20over its respective control. Results revealed that it is highly likely that these rhizobacterial isolates deaminatedendogenous ACC. Therefore, negative effects of stress induced ethyiene could be partially eliminated throughinoculation with ACC-deaminase containing rhizobacteria.