Effect of Plant Growth Regulators and Plant Growth Promoting Rhizobacteria on Physio-chemical properties of Mungbean under Drought Stress

Author: K. Anil Kumar, A. Geetha, Ratna Kumar Pasala, C.V. Sameer Kumar, T. Ramesh and Brij Bihari Pandey

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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.

Keywords

Mungbean, drought stress, PGRs, PGPRs, physio-chemical properties

Conclusion

The world’s population is growing rapidly and is expected to reach 9 billion by 2050, raising concerns about food security. Furthermore, the changing climate scenario threatens food production both in terms of quantity and quality. Drought is one of the most significant abiotic factors that have a negative impact on crop growth and production. In present study, the physio-biochemical parameters of mungbean were recorded under the pot culture experiment after subjecting the plants to both irrigated and stressed conditions. The physio-chemical traits, viz., SPAD chlorophyll meter readings (SCMR), membrane stability index (MSI), protein content, proline content, antioxidant enzymes (catalase, peroxidase, and superoxide dismutase), were recorded after the application of treatments at three different stages of crop growth: flowering, pod filling, and pod maturation. The experimental findings indicated all the physio-chemical traits were significantly varied. The imposition of drought stress conditions caused an overall significant reduction in SCMR (8.8 to 27.0%), membrane stability index (5.0 to 6.8%), and protein content (11.9 to 19.3%). On the other hand, water-limited conditions significantly enhanced the proline content (13.8 to 40.0%) and antioxidant enzymes (20.0 to 54.0%) at all three growth stages in both cultivars compared to irrigated conditions. Also, it was observed that negative effect of drought stress was more pronounced in WGG 42 compared to MGG 385. Among the cultivars, MGG 385 recorded higher SCMR, MSI, and protein content, while cultivar WGG 42 performed superiorly in terms of proline content and antioxidant enzymes under both irrigated and drought-stress conditions. Furthermore, application of PGRs and PGPRs (either alone or in combination) significantly improved the drought stress tolerance and improved the physio-chemical traits of mungbean cultivars. In conclusion, both PGRs and PGPRs in combination were found effective in mitigating the harmful effects of drought stress conditions by way of improving the physio-chemical properties of mungbean cultivars. In addition, the identified concentration of PGRs (salicylic acid and paclobutrazol) and PGPRs (Bacillus subtilis, Bacillus thuringiensis, and Bacillus megaterium) could be also used in other legumes as well as field crops.

References

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How to cite this article

K. Anil Kumar, A. Geetha, Ratna Kumar Pasala, C.V. Sameer Kumar, T. Ramesh and Brij Bihari Pandey (2023). Effect of Plant Growth Regulators and Plant Growth Promoting Rhizobacteria on Physio-chemical properties of Mungbean under Drought Stress. Biological Forum – An International Journal, 15(4): 753-761.