Capacidade fotossintética de plantas de algodoeiro infectadas por ramulose e supridas com silício

Abstract

ResumoNas plantas atacadas por patógenos ocorrem danos nas células do mesofilo, colonização dos espaços intra e intercelulares e fechamento de estômatos, afetando a transpiração, influxo do CO 2 e taxa fotossintética. O uso de silício (Si) é importante para reduzir a intensidade de inúmeras doenças em várias espécies de plantas, além de ter um efeito positivo sobre a capacidade fotossintética. Objetivou-se com este estudo investigar o efeito do Si sobre a capacidade fotossintética de plantas de algodoeiro das cultivares BRS Araçá e FM 993 infectadas por Colletotrichum gossypii var. cephalosporioides supridas (+Si) ou não (-Si) com Si. Avaliaram-se as variáveis de trocas gasosas: taxa de assimilação líquida de carbono (A), condutância estomática (g s ), transpiração (E), razão entre a concentração interna e ambiente de CO 2 (C i /C a ), a eficiência instantânea no uso da água (A/E) e a concentração de pigmentos. Houve redução de A, g s , fixação de carbono, concentrações de clorofila a (cl a ), clorofila b (cl b ) e carotenoides, matéria seca total (MST) e aumento na E e na A/E. Com o fornecimento de Si, as plantas das duas cultivares de algodoeiro aumentaram a A devido ao aumento na g s e na fixação de CO 2 , além de no uso mais eficiente da água. O suprimento de Si aumentou as concentrações de cl a , cl b e carotenoides e MST nas duas cultivares. O Si afetou a fisiologia das plantas de algodoeiro infectadas por C. gossypii var. cephalosporioides, aumentando a resistência à ramulose devido a incrementos na capacidade fotossintética, na concentração de pigmentos e no acúmulo de biomassa.Palavras-chave: Colletotrichum gossypii var. cephalosporioides, fotossíntese, trocas gasosas. Photosynthetic capacity of cotton boll rot infected plants and supplied with silicon AbstractIn plants attacked by pathogens, occurring cell damage of the mesophyll, colonization of intra and intercellular spaces and closing of stomata, affecting perspiration, influx of CO 2 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 CO 2 environment internal (C i /C a ), 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 CO 2 fixation. The supply increased concentrations of cl a cl b , and carotenoids and MST in both cultivars. Therefore, th...

Effects of silicon on biochemical and physiological aspects in Theobroma cacao under inoculation with Moniliophthora perniciosa

“…The beneficial relation of silicon against pathogens is reported is studies with different vegetal species (Zambolim et al, 2009;Carré-Missio et al, 2012;Guerra et al, 2014;Polanco et al, 2014;Santos et al, 2014;Catalani et al, 2016). There was statistical interaction between inoculation and silicon application factors to all variables analyzed, except for Si leaf content (Table 1) and the internal carbon dioxide concentration (Table 2).…”

Physiological indices and growth of ‘Gigante Amarelo’ passion fruit under salt stress and silicate fertilization

“…Silicon supply increases the concentrations of chlorophyll b and carotenoids, as well as the photosynthetic rate of plants (Guerra et al, 2014). The silicon absorbed by the plants is deposited below the epidermal cuticle, forming a double layer of silica in the cells.…”

Anthracnose in açaí palm leaves reduces leaf gas exchange and chlorophyll a fluorescence

“…in açaí palm leaves. In leaf area infected, the tissue death causes stomatal closure because these tissues are unable to carry water, solutes and photosynthesis products (Guerra et al 2014). In bean leaves reduction of g s caused by C. lindemuthianum also resulted in drastic reductions in E (Polanco et al 2014).…”

“…Damage sustained in photosynthetic processes such as gas exchange and chlorophyll a fluorescence are useful indicators of the activity of the photosynthetic apparatus in leaves of cotton infected by pathogens (Guerra et al 2014). Recently, Dallagnol et al (2015) quantified the changes in gas exchange and chlorophyll a fluorescence in rice leaves infected with Bipolaris oryzae.…”