Screening of efficient iaa producing endophytic diazotropic bacteria from ethno medicinal rice of Jharkhand India

There are diverse communities of endophytic diazotropic bacteria present in non-leguminous plants especially in members of Poaceae. These bacteria in addition to nitrogen fixation also produce a wide range of growth promoting substances which shows positive effect on the plant growth and their yield. Endophytic bacteria are those bacteria that reside inside the plant tissue, and directly affect the growth and resistance of the associated plant by the synthesis of phytohormones. Indigenous varieties which form the basis of pure line for genetic plant breeding are at the verge of extinction due to the intervention of hybrid and high yielding variety for increasing productivity. Jharkhand has been the secondary centre of origin of indigenous rice and about 900 varieties are reported to be indigenous to this region. The indigenous and traditional varieties are unique in genotype, and harbours within it lots of beneficial bacteria and have many ethno medicinal properties. But for productivity and yield, the cultivation of these varieties are becoming marginal which is causing huge loss to the rich rice gene pool of the region. In this study four different indigenous rice i.e Sada Gora (SG), Bala Gora (BG), Kala Gora (KG) and Karahni (KH) with lots of ethno medicinal properties were taken for the study. Isolation, characterisation of diazotropic endophytic bacteria from these varieties was done. The bacterial isolates were tested for their ability to produce the plant hormone IAA (indole-3-acetic acid). Out of the 15 diazotropic endophytic isolates 11 isolates were shown to produce IAA. Amounts of IAAproduced in the isolates varied from 22.9 μg ml⁻¹ to 53.4 μg ml⁻¹ of the culture. Out of the four varieties of selected indigenous rice isolates highest level of IAAwas produced by KHR2 and KGS2 (53.4 μg ml⁻¹) followed by SGS2 (45.8 μg ml⁻¹) and KHR1 (41.9 μg ml⁻¹).