Manejo de água e de fertilizante potássico na cultura de arroz irrigado

Abstract

RESUMO -O manejo da água de irrigação e as doses e épocas de aplicação de fertilizantes tornam-se aspectos de extrema importância no êxito do aproveitamento das várzeas para o cultivo de arroz (Oryza sativa L.) irrigado ou este seguido de outras espécies. Com o objetivo de comparar distintas formas de manejo de água e de fertilizante potássico no comportamento do arroz irrigado, foram conduzidos experimentos por três anos consecutivos, em um Inceptissolo. Foram estudados os efeitos de manejo de água (MA 1 -inundação contínua e MA 2 -inundação intermitente seguida de contínua) e o modo de aplicação de fertilizante potássico (K 1 -na semeadura; K 2 -parcelada e K 3 -meia dose parcelada). O manejo de água apresentou efeito mais expressivo sobre o comportamento do arroz que o do fertilizante potássico. A inundação contínua durante todo o ciclo da cultura proporcionou maiores rendimentos de grãos, expressando maiores valores dos parâmetros produtivos, e melhorou a qualidade industrial dos grãos. Com esta irrigação, o parcelamento da adubação potássica aumentou o aproveitamento do fertilizante. Os manejos do fertilizante potássico afetaram diferentemente o comportamento da cultura do arroz nas distintas formas de manejo de água.Termos para indexação: inundação contínua, inundação intermitente, parcelamento de potássio, rendimento de grãos, componentes do rendimento, qualidade tecnológica dos grãos, Oryza sativa. WATER AND POTASSIUM FERTILIZATION MANAGEMENT FOR IRRIGATED RICE CULTIVATIONABSTRACT -Irrigation water levels and timing of potassium fertilization is extremely important for the use of lowlands for irrigated rice (Oryza sativa L.) cultivation in crop rotation. A field experiment was conduced for three consecutive years in Inceptisol to study the effects of water management (WM 1 -continuous flooding and WM 2 -intermittent flooding followed continuous flooding) and mode of potassium fertilizer application (K 1 -at sowing; K 2 -fractional application and K 3 -fractional application of half levels) on grain yield and yield components of irrigated rice. Water management presented expressive effect on rice performance as compared to potassium fertilization. Continuous flooding during whole growing cycle of crop had higher grain yield as well as higher values of yield components and grain quality. Fractional potassium fertilization increased its utilization efficiency. Potassium fertilizer management affected differently rice crop performance according to forms of water management.

Growth and nutrient contents in lowland rice due to phosphorus and potassium fertilization

“…Likewise, Zaratin et al (2004) observed the influence of K fertilization in the yield components of rice grains, in a Brazilian Savannah Oxisol with a K content of 0.21 cmol c kg -1 (similar to the level of our experiment: 0.22 cmol c kg -1 ). Santos et al (1999), working in a tropical soil with water flooding, showed that, in an area with pH (water) 4.9 and a level of K = 0.18 cmol c kg -1 (lower levels than in our experiment), split potassium fertilization provided increases in the number of grains per panicle and rice grain yield, in relation to the lowest K levels. Other studies on K level effects, in rice grown on the floodplains of the Tocantins state, also reported significant increases in rice yield components and grain yield associated with this nutrient (Fageria et al 1990.…”

“…This condition may be aggravated by the flooding of the area, as happened in this experiment. Santos et al (1999), who studied different levels of K and different water management scenarios in tropical soils, showed that, in a continuous water flooding, fractional K fertilization increased its utilization efficiency, because it reduced its leaching. Thus, the application of increasing rates of K did not provide significant increases in the evaluated parameters, probably due to the low pH and the predominance Figure 2.…”

Cooking quality of upland and lowland rice characterized by different methods

“…Similar results were found by Fonseca et al (2004) for cultivar BrS MG Curinga and by Ferreira and Pinheiro (2003) for cultivar BrS Primavera, both upland rice cultivars. According to Santos et al (1999), cultivars with intermediate GT showed a good culinary behavior; and consequently it became a requirement for the release of new cultivars in Brazil. According to these authors, when a rice variety presents high gelatinization temperature, it means that its grains need more water and time to cook, whereas the cultivars with intermediate or low gelatinization temperatures need less water and time to be cooked resulting less energy input and expense.…”

Requisitos de clientes para o desenvolvimento de um implemento a fim de fechar taipas abertas para drenagem

“…As culturas em áreas de várzea têm seu comportamento extremamente influenciado pelo manejo, haja vista que estes locais apresentam características químicas e físico-hídricas bastante distintas (SANTOS et al, 1999). A característica comum, dominante nos solos de várzea do RS é a deficiente drenagem natural, devido à topografia predominantemente plana e às suas características físicas (SILVA & PARFITT, 2004).…”