Does Potassium Silicate Improve Physiological and Agronomic Traits and Oil Compositions of Rapeseed Genotypes Under Well-Watered and Water-Limited Conditions?

A field experiment (2018-2020) was arranged as factorial split-plot in a RCBD with three replications to assess the influences of potassium silicate on rapeseed genotypes under well-watered and drought stress conditions. Main plots included two regimes of full irrigation and withholding irrigation from silique setting and foliar spray of potassium silicate at two levels of non-application and potassium silicate application (4 g l(-1)). Subplots contained seven genotypes of WRL-95-13, WRL-95-15, WRL-95-17, WRL-95-20, WRL95-23, WRL-95-28, and Nafis. Drought stress increased stomatal resistance, canopy temperature, soluble carbohydrate content, and proline content; by contrast, the chlorophyll content, relative water content (RWC), seeds per silique, silique per plant, thousand-seed weight, seed yield, and water use efficiency (WUE) were reduced when the rapeseed plants experienced drought stress. The oil content and quality of genotypes were higher in the well-watered irrigation regime than in the drought stress regime. The spraying of potassium silicate helped to improve the growth of rapeseed genotypes by increasing the RWC and chlorophyll content and reducing the stomatal resistance and canopy temperature in both irrigation regimes. The increase in the contents of oleic and linoleic acids and reduction in the contents of erucic acid and glucosinolate caused an enhancement in the oil quality when potassium silicate was applied. Overall, the high quantity and quality of oil can be achieved in rapeseed agroecosystems through full irrigation and spraying potassium silicate.