Desenvolvimento do sorgo (Sorghum bicolor L. Moench) em função de doses de nitrogênio e potássio.

Abstract

Sorghum bicolor [L.] Moench) is a warm climates plant with xerophilic characteristics that serves as a good alternative in the production of grains and fodder for animal feed, because it has efficient mechanisms of resistance to climatic adversities and does not require high Fertility of soils as required by other cereals such as corn. The objective of this work was to evaluate the development of sorghum as a function of soil nitrogen and potassium fertilization, determining the appropriate doses. The experiment was conducted in 2016 at the Federal Rural University of the Amazon (Belém - Brazil) in a greenhouse, where 64 experimental units composed of pots filled with dystrophic Yellow Latosol with two sorghum plants were used. The treatments used were 4 doses of nitrogen (0, 80, 160 and 320 kg ha-1 of N) and 4 doses of potassium (0, 50, 100 and 200 kg ha-1 of K) with 4 replicates, 4x4 in a completely randomized design. The set of analyzed variables included phytometric, ecophysiological, biochemical and nutritional data of sorghum plants. The results showed that all the echophysiological variables were positively influenced by the increasing effect of the N and K doses as separate sources of variation, except for the intercellular carbon variable and the total chlorophyll content, which responded better to the interaction between doses and only to the greater dose of N, respectively; Nutrient levels (N, P and K) in roots and leaves were also positively influenced by increasing doses of nutrients, with better results obtained from the interaction between the two nutrient doses, except for the N content in the roots, which was influenced only by the N rates, and for the N content in the leaves, which was not influenced by any of the sources of variation; The phytometric variables also had a positive influence due to the two sources of variation (doses of N and K), separately, except for the mass of dry matter of the roots, which responded significantly to the interaction between doses, the height of the plants, whose response occurred alone at the application of N doses, and the number of leaves, which did not respond to any of the sources of variation.