ENVIRONMENTAL IMPLICATIONS OF DIVERSE RHIZOSPHERIC COMMUNITIES OF BACTERIA FOR NATURAL WEED SUPPRESSION ALONGSIDE CROP GROWTH STIMULATION

Diverse communities of bacteria inhabiting the rhizosphere of plants are known for possessing complex mechanisms which impart implications on the growth and economic performance of plants. Present work is the key to the interest of researchers to maneuver these mechanisms to the benefit of mankind and resolve present day grave challenges of food security and environment. A large collection of rhizobacterial strains has undergone exhaustive screening process of their testing for the extracellular production of known plant growth inhibitory as well as stimulatory substances. The best candidate strains from the metabolite tests were applied under in vivo studies to plants which included three most noxious weeds of wheat (wild oat, littleseed canary grass and broadleaved dock) and wheat crop. The strains with maximum weed inhibition activities alongside non-deleterious or stimulatory effects on wheat were selected to be further tested in multiple field experiments. In weed control field trials, biomass of wild oat was inhibited from 14.3 to 52.1 percent, that of littleseed canary grass from 43.8 to 52.2 percent, and that of broadleaved dock was restricted from 17.9 to 44.0 percent where attack of these weeds, respectively, caused 60.8, 59.9 and 86 percent loss of grain yield of wheat. In crop growth testing trials, three of the five applied strains remained non-inhibitory as well as non-stimulatory to the wheat crop whereas two strains stimulated growth, yield and physiology of wheat. They increased the grain yield of wheat up to 34.3 and 40.3 percent. 16s rRNA sequencing technique identified all these strains to be pseudomonads. This work forms the framework of biobased products for control of weeds and higher production of wheat. This work promotes non-chemical natural means of food production indicating a multitude of benefits ranging from sustainability of the environment to healthy foods and enriched biodiversity. 1. University of Agriculture Faisalabad, Pakistan, 2. Higher Education Commission, Islamabad, Pakistan