Abstract

Since silicon and potassium are nutrients that influence plant physiological and biochemical aspects, the combined use of these minerals in the fertilization of cultivated plants has been increasingly investigated. This study aimed to evaluate the gas exchanges (Net photosynthesis, Stomatal conductance, Transpiration, Water use efficiency, Carboxylation efficiency, Internal carbon concentration, Chlorophyll a, b, total, Carotenoids and the Chlorophyll a/b ratio) of three castor bean cultivars in response to the foliar application of potassium silicate (PS). The assay in design of randomized blocks, was conducted in a factorial 5 × 3, five doses of potassium silicate (0; 222; 444; 665 and 836 mg L^-1) and three varieties of castor bean (BRS Energia, BRS 149 Nordestina and BRS 188 Paraguaçu), with three replications and 45 plants per. The promising effects of foliar fertilization using PS in castor bean plants depend on the genotype. Foliar application of PS increases photosynthetic capacity, stomatal conductance, water use efficiency, chlorophyll a, b, total, carotenoids and the chlorophyll a/b ratio, besides reducing water losses through transpiration.

Key words: Foliar spraying, Photosynthesis, Ricinus communis L., Silicate fertilization