Fertilizing potassium in rice cultivation in sandy soils of tropical lowland

The rice plant is very demanding in nutrients, with potassium being that the plant nutrient further accumulates, and is essential to many physiological and biochemical processes in the plant. The objective of this study identify appropriate doses of potassium in the culture of rice, grown in sandy soils of lowland tropical rainforest in the state of Tocantins. The experiment was conducted in hydromorphic soil type Gleysol Humic of irrigated lowland, in the Araguaia-TO Formoso region. We used the experimental randomized block design, in a factorial 2 x 5, with four replications, two cultivars (Irga-424 and Irga-423) and five doses of K (60, 90, 120, 150 and 180 kg ha K -1), applied in the form of potassium chloride. Each experimental plot consisted of twenty-seven lines of 15 m in length, spaced 0.17 m between rows. The floor area was composed of the four central lines in the length of two linear meters. The characteristics evaluated were plant height, number of panicles m2, grain yield, weight of hundred grains, potassium content and chlorophyll index. Data were subjected to analysis of variance and regression at 5% probability by F test The cultivaresnao responded to the increased potassium fertilization in sandy soils of tropical lowland; the average yield was reached with the basic fertilization, sedo 6827.42 and 5215.35 kg ha-1 for Irga-424 and Irga-423, respectively.