Bioestimulantes na cultura do arroz inoculado com Pyricularia grisea

Abstract

Due to the various phytosanitary problems in different cultures and with the constant emergence of resistant pathogens, agribusiness has been developing new techniques and technologies that are combined in an attempt to minimize production costs and improve effective quality of some products, in order to increase productivity. Due to the little knowledge about hormonal control agrochemicals and the correlation with the disease control, the objective of this work was to evaluate a biostimulant source based on algae and silicon extract and a commercial product based on micronutrients, studying the influence of different concentrations on rice development and productivity, inoculated with the fungus Pyricularia grisea (Brusone). The experiment biological test) was carried out in a greenhouse belonging to the Federal University of Uberlândia. Were 10 kg pots were used, with soil classified as Quartzene Neossol, using the cultivar BRS Atalanta, adapted to flooded cultivation. The design was entirely causalized, with three repetitions and factorial 2x2x2 + 2, and the treatments consisted of absence and presence of Pyricularia grisea (1.5 x 105 mL-1) and two doses (1.50 and 3.00 L ha-1) of two biostimulatory sources based on Ascophyllum nodosum extract and two additional (0.00 L ha-1 ), with and without inoculation. Product A contains concentrations of 5.7% zinc, 17% phosphorus, 13% nitrogen and 2.5% manganese, while Product B (a source containing potassium silicate enriched with zinc), contains concentrations of 1.5% silicon, 1.5% potassium and 0.5% zinc. The following values ​​were evaluated: chlorophyll A and B values ​​in the tillering and elongation; leaf contents of silicon, macro and micronutrients; mass of root and shoot dry matter, number of panicles; amount of burnt grains; weight of grain without straw; total weight (grain + straw); broken grain weight and nitrate assessment reductase. The assumptions of the data obtained were tested, and the means were compared by the Tukey and Dunnett test, both at 0.05 significance. The use of biostimulants based on of Ascophyllum nodosum extract, containing micronutrients (Product A) and silicate of potassium + zinc (Product B), via leaf, in flooded rice culture, when inoculated with Pyricularia grisea, provide higher foliar contents of phosphorus and silicon and a lower number of panicles. The application of the biostimulant containing potassium silicate and enriched with zinc (Product B) provides higher leaf iron content and lower grain weight broken and when applied the dose of 3.0 L ha-1, provides higher leaf zinc content and, at a dose of 1.5 L ha-1 , lower values ​​of chlorophyll B in the stretching phase, regardless of inoculation.