Study on the Effects of Seed Biological Treatments on Yield and Some Biochemical Parameters of Rapeseed Genotypes under Water Stress Conditions

Water shortage seriously threatens crop growth and development especially in semi-arid areas. Association of plants with beneficial soil microorganisms is a strategy for plant adaptation to environmental stresses. In this study, the effect of seed inoculation of rapeseed genotypes with mycorrhiza-like fungus (Piriformospora indica) and growth-promoting bacterium (Arthrobacter siccitolerans) was investigated on some yield and physiological indices under non-stress and drought stress conditions. The results showed that the stress reduces grain yield (19.5%) and oil concentration (23%) while physiological attributes including activity of anti-oxidant enzymes (catalase, superoxide dismutase, ascorbate peroxidase and malondialdehyde) and content of proline increased. Seed treatment with P. indica and A. siccitolerans under stress condition reduced the activity of enzymes and content of proline whereas improved grain and oil yields compared to the non-stress condition. Although the alleviation effect of bacteria and fungi on the studied traits was similar, the effect of fungi on proline content and oil yield became more noticeable. Also, under non-stress condition, the use of these microorganisms reduced the activity of enzymes and content of proline. It is noteworthy that due to the high variability of the proline content, it can also be introduced as an indicator of stress in biological treatments assessment. Overall, the results showed that despite the differences in the response of genotypes to treatments, the application of both microorganisms increases grain yield and oil yield under both non-stress and water stress conditions, and the biological treatments, particularly P. indica could be used to alleviate water stress effects on rapeseed genotypes.