Exogenously applied silicon and zinc mitigates salt stress by improving leaf pigments and antioxidant activities in canola cultivars

Abstract Globally, climate change and global warming induced salt stress is intensifying rapidly which has resulted in food supply constraints. The exogenous application of zinc (Zn) and silicon (Si) might serve as potent strategy to boost productivity of oil seed crops including canola, however research gaps exist regarding their dose optimization. A trial was conducted with an aim to determine the phenotypic divergence among canola cultivars under varying doses of Zn and Si applied solely and in conjunction with each other. The trail was comprised of two promising cultivars of canola (Sandal and Rachna) and seven foliar treatments including control, Si = 35 ppm, Si = 70 ppm, Zn = 35 ppm, Zn = 70 ppm, Si + Zn = 35 ppm and Si + Zn = 70 ppm applied under two level of salinity stress (SS). Different morphological and physiological traits of canola cultivars were taken as response variables. Completely Randomized Design (CRD) with factorial arrangement was used with three replications. 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. Additionally, root length (11.17 cm) and their fresh (2.63 g) and dry weights (0.78 g) were enhanced with the increasing SS level. 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).