Effect of plant growth regulators and plant growth promoting rhizo-bacteria on physio-chemical properties of mungbean under drought stress.

Abstract

Among the different abiotic stress, drought is one of the most significant abiotic factors that have a negative impact on crop growth and production. In Telangana, post-rainy season grown mungbean frequently experiences drought at different growth stages and are altered pigment synthesis and metabolic processes. The present investigation was formulated to find out the potential role of plant growth regulators and plant growth promoting bacteria in improving physio-chemical properties of mungbean under drought stress conditions. The whole study was carried out at the Indian Institute of Oil Research (IIOR), Rajendranagar, Hyderabad, during the Kharif season, 2021–22. The study was conducted by arranging pots in a split-plot design with three replications and experimental material comprised two varieties of mungbean cultivars, WGG42 and MGG385. Various combinations of plant growth regulators (salicylic acid at 100 ppm and paclobutrazol at 150 ppm) and plant growth promoting bacteria (Bacillus subtilis, Bacillus thuringiensis, and Bacillus megaterium) were given as treatment to the crop. The plant growth regulators (PGRs) were given to the crop at 20 and 35 days after sowing (five days before flowering and five days after flowering), whereas the plant growth promoting bacteria (PGPRs) were applied as a seed treatment. Different physio-biochemical parameters were recorded during the experiment after subjecting the plants to irrigated and stressed conditions. The results indicated that drought stress conditions caused a reduction in SPAD chlorophyll meter readings, membrane stability index, and protein content, whereas increased proline content and antioxidant enzymes at all three growth stages. Furthermore, the combined application of all PGRs and PGPRs (seeds inoculated with Biotilis, Lipel, and P Sol B at 10 g/kg of seed each, paclobutrazol at 150 ppm and salicylic acid at 100 ppm) to the mungbean cultivars was found to be most promising at all the growth stages compared to the rest of the treatments and control. Therefore, from the present study, it can be inferred that application of PGRs and PGPRs were highly effective in improving the physio-chemical properties of mungbean.