Differential responses produced by silicon (Si) on photosynthetic pigments in two pepper cultivars exposed to water deficiency.

This study aims to (i) investigate the silicon action on photosynthetic pigments, as well as (ii) to determine the optimal Si level for each cultivar, and (iii) establish a possible interference on carbon compounds in two 'Capsicum annuum' cultivars exposed to water deficiency. For this purpose, a completely randomised factorial design was conducted, composed of four water and Si combinations (water deficit + 0.00 Si, water deficit + 0.25 Si, water deficit + 1.00 Si, and water deficit + 1.75 mM Si) applied on two cultivars (Ikeda and Vermelho Gigante). Some parameters such as relative water content and temperature in leaf, pigments, and carbon compounds were evaluated. The results showed that both cultivars have high water content and temperature in leaf and sucrose content after Si application. The Si application caused reduction in total soluble carbohydrates of two cultivars, with the values of 1.26 and 0.96 mM Si for Ikeda and Vermelho Gigante, respectively. The cultivars presented differential behavior linked to photosynthetic pigments, in which only Vermelho Gigante cultivar showed increase, after 0.99 mM Si treatment.