In Planta Screening of Maize Seed Endophytic Bacteria for Potential Applications under Dryland Conditions

Seeds harbor endophytic bacteria is capable of vertical transmission to next generation. These contribute to host plant's growth and adaptation to stress conditions. Such bacteria need to be developed for improving crop productivity. The present investigation was aimed at selecting promising maize seed endophytic bacteria (MSEB) for plant growth promotion under drought conditions through multilevel screening approach. Two levels of pot screening conducted using sterile soil helped in selecting eleven (out of eighty) promising isolates based on their positive influence on plant growth and biochemical parameters of maize under drought conditions. The third level pot screening was conducted using unsterile soil to evaluate the performance of selected 11 isolates under drought conditions. Pre-treatment of the seeds with MSEB isolates exhibited positive influence on plant growth and physiological parameters of maize under drought stress. Treatment with Corynebacterium hansenii MSEB 3 was found to be best in improving chlorophyll content (18.07%), relative water content (29.88%), and leaf proline (143.47%) besides improving other growth parameters over uninoculated control. Whereas, pretreatment with Bacillus subtilis MSEB 78 was found to be superior in improving shoot fresh weight (33.12%) and dry weight (54.36%) over control treatment. Significant positive correlations were observed between chlorophyll content and shoot fresh biomass, proline and relative water content, indicating its importance as a screening parameter for drought tolerance. Further, soil moisture content also showed significant positive correlation with shoot length, shoot fresh biomass and shoot dry biomass. The isolates selected in the present investigation can be exploited for agricultural benefits and can also add to the knowledge on plant-endophyte interactions under stress conditions.