Exogenously Applied Silicon and Zinc Mitigates Salt Stress by Improving Leaf Pigments and Antioxidant Activities in Canola Cultivars

Exogenous application of zinc (Zn) and silicon (Si) might serve as potent strategy to boost productivity of oil seed crops including canola in a saline environment. A trial was conducted with an aim to determine the phenotypic divergence among canola cultivars (Sandal and Rachna) under varying doses of Zn and Si (35 ppm and 70 ppm) applied solely and in conjunction with each other under two level of salinity stress (SS). Different morphological and physiological traits of canola cultivars were taken as response variables. The results revealed that SS adversely affected the leaf pigment and shoot length along with their fresh and dry weights, while antioxidant activities were increased especially under exogenous application of Si+Zn=70 ppm. Under salinity stress conditions the root length and their fresh as well as dry weight increase as compared to the controlled plant which are grown under normal conditions without salinity stress. Moreover, canola cv. Sandal outperformed in terms for shoot-root length and their fresh and dry weight as well as the leaf pigments contents. The co-application of Si+Zn=70 ppm exhibited the highest shoot-root length (17.64 cm-16.47 cm) and their fresh (2.60 g-1.89 g) as well as dry weight (0.73 g-0.29 g). The same treatment combination resulted in the maximum leaf pigments such as chlorophyll a (6.63 g/mg FW), chlorophyll b (4.37 g/mg FW) and total carotenoids content (2.38 g/mg FW).