Fluorescent pseudomonadscontribute to the enhanced growth and yield of rice cultivated under system of rice intensification (SRI)

Abstract

The System of Rice Intensification (SRI) is an innovative method of rice (Oryza sativa) cultivation that combines many farm practices. Though the benefits of SRI are obvious, the underlying principles in enhanced yields are not yet scientifically analyzed. Two important components of SRI are keeping the rice field moist without flooding and frequent weeding out practices that enhance the aerobic conditions which in turn improve soil biological activity including enhanced root growth and activity of aerobic soil organisms. We have taken up the present investigations, with the premise that soil microorganisms especially fluorescent pseudomonads (FLPs), whose role in enhancement of plant growth is unequivocal, may contribute to the enhanced growth and yield of rice cultivated under SRI.The results of present investigations revealed that rice cultivated under SRI harboured more the population of FLPs in rhizosphere than non-rhizosphere soil. Screening of rhizospheric FLPs isolates has revealed that many of the isolates possessed the ability of producing growth promoting substances like IAA, GA, siderophores, ‘p’solubilization. Some selected strains have also shown resistance towards heavy metals, salts and pH. They have also exhibited significant antifungal activity and enhanced the seed germination and efficient root colonization. Further, artificial inoculations have also clearly shown to enhance the growth in terms of height, dry weight of shoot and root. Thus, the results substantiate the role of FLPs for the enhanced growth and yield of rice cultivated under SRI.