Recobrimento de sementes com silício e seu efeito no desenvolvimento da antracnose e murcha de Fusarium na cultura do feijão.

Abstract

The a im of this study was: a) to evaluate the effect of different doses and sources of Si through the coating of seeds on the physical quality, physiological and sanitary conditions of seeds as, to determine the concentration of silicon and calcium absorbed in bean seedlings; b) to evaluate the performance of seedlings inoculated with Fusarium oxysporum f. sp. phaseoli and covered with different sources of Si, during emergence and in the expression of biochemical mechanisms, involved in post-infection responses at different times and; c) to evaluate the effect of seed coating with Si in response to infection in a susceptible and resistant Colletotrichum lindemuthianum, on the physiological and sanitary potential of seeds and seedlings, during the initial development of the bean culture. Different doses were tested (0; 45; 90; 135 and 180g Si 100 kg-1 of seeds) and sources of Si [Agrosilício®, calcium silicate and rice husk ash (AHC)] by seed coating, whether or not inoculated by the water restriction method. The covering of seeds composed of Agrosilício®, AHC and calcium silicate, does not change the physical quality of the seed, provides vigorous seedlings, without compromising the end emergency. Seeds coated with doses of calcium silicate and AHC, increase the concentration of Si in roots, but reduce the concentration of calcium (Ca), while the Agrosilício® increases the concentration of Si in leaves and Ca in the roots. Different sources and doses of Si do not control pathogens associated with bean seeds. The association of F. oxysporum f. sp. phaseoli in seeds impairs seedling emergence and growth. Si has little effect on responses in uninoculated seedlings, but raises lignin concentration. In the presence of F. oxysporum f. sp. phaseoli, Si triggered better initial seedling performance, favored and enhanced the defense mechanisms. The Si source supplied by Agrosilício® provides early rapid anticipation of peroxidase, which may have ameliorated and delayed the damage of the pathogen in the seedlings. The AHC as a source of Si, although it has contributed to the potentiation of defense enzymes in the later stages of infection was not efficient in controlling the incidence of the disease. The seed coating with Si decreases the incidence and severity of C. lindemuthianum and provides greater growth of the bean seedlings. The effect of responses potentiated by Si has greater expressiveness in the cultivar of greater susceptibility.