Silício potencializa respostas bioquímicas e histocitológicas do trigo contra Pyrenophora tritici-repentis

Abstract

Silicon (Si) is a mineral element that when absorbed by plants give it numerous benefits, especially in the control of biotic diseases. Based on this, the objective of this study was to investigate the effects of Si supply to wheat plants in reducing the intensity of the yellow spot in a susceptible cultivar (Horizonte) and a moderately resistant (Quartzo), elucidating the effects of this element on biochemical defense mechanisms (Chapter I), as well as in the histo-cytological defense responses against the process of infection by P. tritici-repentis on the leaves of wheat plants (Chapter II). Si supply reduced the yellow spot severity, for both varieties, up to 40% due to the increase of the incubation period and decreases the efficiency of infection, number of lesions per cm 2 , rate of lesion expansion, final lesion size. Enzymes involved in plant defense system as superoxide dismutase, peroxidase and chitinase, showed greater activity plants in inoculated and supplied with Si. Plants supplemented with Si also showed an increase in the concentration of phenolic compounds. The lipoxygenase enzyme, which was a unique response observed in cv Quartzo, increased its activity in response to pathogen inoculation, but was unaffected by Si. For histo-cytological responses, it was observed that in plants supplied with Si there was a reduction in the degree of cell death in the infection sites, which was correlated with the accumulation of phenolic compound and hydrogen peroxide at the site infection in the epidermal cells. The results of this study demonstrated the potential of Si to enhance the resistance of wheat plants to yellow spot, through the enhancement of biochemical defense responses or through interventions in the infection process of the pathogen. In this context, in a current agriculture which advocates for sustainable production without harm to the environment, the Si becomes a promising alternative control measure to be used in the integrated management of the yellow spot.