DOSES DE URÉIA, SUPERFOSFATO TRIPLO E CLORETO DE POTÁSSIO NA PRODUÇÃO DE MUDAS E NO ESTABELECIMENTO DE PLANTAS DE Hymenaea stigonocarpa Mart. ex Hayne SOB RESTRIÇÃO HÍDRICA

Abstract

Nutrition and water deficit are two important factors that affect the growth and development of plant species, especially when inserted in the context of global climate change. Therefore, the aim of the present study was to determine the morphoanatomical and physiological characteristics of Hymenaea stigonocarpa Mart. ex Hayne seedlings, integrated with the efficiency of using nitrogen (N), phosphorus (P) and potassium (K) to tolerate the water deficit effects. The first stage of the experiment was carried out in a completely randomized design (DIC), with 5 doses of nitrogen (0, 75, 150, 225, 300 g m-3 of N: urea), 5 doses of phosphorus (0, 150, 300 , 450 and 600 g m-3 of P: triple superphosphate) and 5 doses of potassium (0, 40, 80, 120 and 160 g m-3 of K: potassium chloride), with 4 repetitions, each consisted of eight sample units. The seedlings were produced in tubes of 100 cm3, filled with pig sludge, carbonized rice husks and vermiculite in the proportion of 1: 1: 1. The parameters measured during the nursery phase were: plant height and stem diameter biometry, biomass accumulation, gas exchange, chlorophyll a fluorescence, pigment index, N, P, K content and accumulation, micromorphometry and leaf anatomy. Nitrogen fertilization increased the parameters of growth, biomass, secondary pigment index (anthocyanins and flavonoids), photochemical efficiency and N accumulation in the estimated dose of 300 g m-3 of nitrogen, on the other hand, there was a reduction in leaf epidermis and photo effect inhibition by the lack of response due to the unchanged Ci/Ca - A/Ci ratio. Phosphate fertilization had a significant effect on growth, gas exchange, chlorophyll a fluorescence, anthocyanin indices, chlorophyll indices, increased leaf abaxial epidermis of biomass accumulation at a dose of 600 g m-3 of phosphorus. Potassium fertilization reduced the growth and thickness of the chlorophyll parenchyma, due to the effect of stomatal limitations, however, on the other hand, it promoted the production and accumulation of seedling biomass at the dose of 80 g m-3 of potassium. With the doses of nitrogen, phosphorus and potassium previously selected, the seedlings were transplanted into pots containing 4 kg of RED LATOSOL and sand in the proportion of 2:1, later transferred to the greenhouse. The design of the second experiment was in DIC, in a 2x3 factorial scheme composed of treatments, nutritional status (plants with supplementary fertilization and without supplementary fertilization) and water replenishment (100%, 50% and 30% of field capacity - CC), with 4 repetitions. The doses of 300 g m-3 of nitrogen, 600 g m-3 of phosphorus and 80 g m-3 of potassium were effective in alleviating the deleterious effects of water deficits of 30% and 50% of WC. The control treatment with plants without supplementary fertilization responded to the maximum water replenishment of 50% and 100% of WC.