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The present study was conducted with the aim to isolate, characterize, and identify the promising zinc-solubilizing rhizobacteria found naturally in the rhizosphere of canola (Brassica napus L.) plants. The study investigated the roles of these strains in nutrient acquisition and assimilation of extracellular molecules such as hormones and secondary metabolites. Ten isolated promising zincsolubilizing strains (CLS1, CLS2, CLS3, CLS6, CLS8, CLS9, CLS11, CLS12, CLS13, and CLS15) were selected and characterized biochemically. Almost all the tested strains were Gram-positive, could fix nitrogen, and were positive for indole acetic acid, HCN, exopolysaccharides, and siderophore production. These effective zinc-solubilizing strains were identified through 16S rRNA gene sequencing. Based on the amount of solubilized zinc and halo zone diameter, four potent strains (CLS1, CLS2, CLS3, and CLS9) were selected for pot and field evaluation. Among all the identified bacterial genera isolated from the rhizosphere of the same host plant at different sampling sites, Priestia aryabhattai was found most abundant and found at all three sampling sites. The strains Priestia megaterium, Staphylococcus succinus, and Bacillus cereus were found at two different sites. Bacillus subtilis was found at only one site. These strains have a number of plant growth-stimulating characteristics as well as the ability to colonize plant roots successfully. The results indicated that inoculation of all these four zinc-solubilizing tested strains enhanced the plant growth, oil contents, and yield attributes of canola as compared to non-inoculated control with fertilizer levels. Staphylococcus succinus (CLS1) was first reported as a zinc solubilizer and associated with canola. Priestia aryabhattai (CLS2) and Priestia megaterium (CLS9) were found to be the best strains, with the most pronounced beneficial effect on canola growth and yield traits in both pot and field conditions. The sitespecific dominance of these strains observed in this study may contribute toward decision-making for the development of specific inocula for canola. Therefore, identification of these strains could help in providing adequate amount of soluble zinc along with enhanced plant growth, yield, and oil content of canola. [ABSTRACT FROM AUTHOR]

Under the current climate change scenario, water stress is one of the key factors that reduce the production of crops. Gibberellic acid (GA3) is an efficient endogenous plant hormone that shows a vital role in plant growth and development. Production of canola (Brassica napus L.) and its oil contents are severely affected under drought stress. The present study was conducted to investigate the potential of GA3 in alleviating drought stress in canola. Three levels of GA3 (G0 = 0 mg L−1, G1 = 100 mg L−1, and G2 = 150 mg L−1) as foliar applications were applied under two drought-stress conditions (D1 for three days of drought stress and D2 for six days of drought stress) on two canola varieties (Punjab canola and Faisal canola). Irrigation was applied after 3 weeks of germination, while foliar application of GA3 was done at intervals of 4 and 5 weeks after germination. When comparing the output of all the GA3 treatments, it was noticed that in G0 = 0 mg L−1 (control plants), water-stress conditions markedly reduced plant production and seed oil contents but increased protein and linoleic acid. With the application of G2 = 150 mg L−1, the maximum values of plant height (90.83 cm), no. of siliqua plant−1 (15.50), seed siliqua−1 (15.55), siliqua length (5.08 cm), relative water contents (77.60%), yield plant−1 (0.46 g), chlorophyll a (0.62), carotenoid contents (39.52), and oleic acid contents (60.20) were recorded under drought stress. Based on these results, it is concluded that the adverse effect of drought stress on different yield parameters of canola could be ameliorated by the exogenous application of GA3 through foliar application at a dose of 150 mg L–1. Moreover, the same treatment improves the quality parameters, i.e., the oleic acid contents of the oil, obtained from the canola. [ABSTRACT FROM AUTHOR]