Foliar Application of Silicon Alleviates Adverse Effect of Drought Stress by improving Growth, Physiological attributes, and Antioxidant Defense of Camelina (Camelina sativa L.) and Canola (Brassica napus L.)

Abstract

Purpose: Drought stress is a global phenomenon that poses harmful impacts on crop growth and development leading to yield losses in oilseed crops. Canola and camlina are highly sensitive to drought stress. The present study investigated the role of foliar-applied silicon to alleviate the harmful effect of drought stress in camelina and canola genotypes. Methods: Different concentrations of silicon (Si) foliar applications (NS= no spray, WS= water spray, Si-2= 2 mM Si, Si-4= 4 mM Si, Si-6= 6 mM Si) were used along with different levels of drought stress i.e., control (100% field-capacity) and drought stress (50% field-capacity), for two genotypes of camelina (611 and 618) and two canola genotypes (Super and Rachna). Results: Drought stress caused marked reductions in the growth of canola and camelina genotypes as compared with control-100% field capacity. Compared to control, drought stress decreased shoot length of canola and cameline by 25% and 28%, respectively. Physiological attributes were also decreased under drought stress as photosynthetic rate, relative water content (RWC), and chlorophyll content were decreased by 39, 38 and 42% in canola and 35, 45, and 39% in camelina, respectively, as compared to control. Drought stress was found to increase the oxidative damage in both crops. Foliar applications of Si improved the morpho-physiological and biochemical attributes in canola and camelina genotypes as compared to NS. Silicon applications at 4 mM upregulated the activities of catalase, superoxide dismutase, and peroxidase were increased by 16, 18, and 12% in canola and 17, 14, and 15% in camelina respectively, reducing the electrolyte leakage as compared to NS. Under drought stress, maximum improvements in plants performances were observed when Si was foliarly applied at 4 mM followed by 6 mM and 2 mM. Among the genotypes, canola genotype Rachna showed better performance as compared to Super, while camelina genotype 618 showed better performance as compared with 611. Conclusion: In crux, Si foliar application particularly at 4 mM improved the morpho-physiological and biochemical attributes in canola and camelina genotypes under drought-stressed conditions. The better growth and greater stress tolerance of Si-applied plants was attributed to maintaince of plant water status and photosynthetic pigments, lower oxidative damage, and higher activities of antioxidant enzymes under drought.