In plants attacked by pathogens, occurring cell damage of the mesophyll, colonization of intra and intercellular spaces and closing of stomata, affecting perspiration, influx of CO2 and the photosynthetic rate. The use of Silicon (Si) is important to reduce the intensity of numerous diseases in several species of plants, as well as having a positive effect on the photosynthetic capacity of plants. The objective of this study, was to investigate the effect of Si on the photosynthetic capacity of cotton plants of cultivars BRS Araçá and FM 993 infected by Colletotrichum gossypii var. cephalosporioides and supplied with (+Si) or not (-Si) silicon. Been evaluated variables of gas exchange: carbon assimilation rate (A), stomatal conductance (g s), transpiration (E), ratio between the concentration and CO2 environment internal (Ci/Ca), efficiency of water use (A/E) and pigment concentration. There were reduction of A, the gs, carbon fixation, chlorophyll a concentrations (cl a), chlorophyll b (cl b) and carotenoids, total dry matter (MST) and increasing of E. The supply of the two cotton cultivars due to increase in g s and CO2 fixation. The supply increased concentrations of cl a cl b, and carotenoids and MST in both cultivars. Therefore, the Si affect the physiology of plants of cotton infected by C. gossypii var. cephalosporioides, increasing the resistance to Colletotrichum gossypii in photosynthetic capacity increments due to the concentration of pigments and in the accumulation of biomass.
Colletotrichum gossypii var. cephalosporioides; photosynthesis; gas exchange abstract
