Plant growth promotion and alleviation of salts in rice by Paenibacillus spp

Abstract

Soil salinity plays an evil role by making a crop highly fragile and thereby deteriorating its productivity. Rice is a salt sensitive crop and soil salinity is the single most widespread soil toxicity problem facing rice production. Major problem soils under which rice is grown are Sodic soils, Saline soils (includes inland and coastal saline soils) and Saline-sodic soils and these soils adversely affect growth and productivity of rice. In this study, Paenibacillus castaneae VPB1 and Paenibacillus stellifer KVPB5 were evaluated for alleviating salt stress. The isolates could tolerate salinity stress up to 15% NaCl. The isolates possessed traits like nitrogen fixation, phosphorous solubilisation, siderophore and IAA production. The two isolates were taken for gnotobiotic assay under salt stressed conditions. A considerable growth of rice seedling (CO-51) was noted under gnotobiotic assay. The pot culture studies were performed under different salt stress (0 mM NaCl, 50 mM NaCl, 100 mM NaCl). Among various treatments, the treatment T5 (Paenibacillus castaneae VPB1 + 50 mM NaCl) recorded maximum shoot length of 19.7 and 56.0 cm and root length of 18.6 and 37.5 cm at 30 and 60 DAS respectively. Paenibacillus castaneae VPB1 plus 50 mM NaCl significantly increased the number of grains (201 plant-1) treatment without bacterial inoculation with salt stress. Hence, it is concluded that Paenibacillus spp. could be recommended as potential bio-inoculant to rice crop under salt stressed conditions after field evaluation.