Necessidade hídrica e produtividade da batata (Solanum tuberosum L.) sob diferentes lâminas de irrigação em cultivo agroecológico

Abstract

The potato is a basic food source and an adequate irrigation and fertilization are necessary for a sustainable crop management. Within this context, organic agriculture is inserted as an alternative to ensure productivity and to conserve natural resources. The objectives of this research were: measuring the water consumption of potato; obtaining the water use production function; evaluating the interaction of the absence and presence of nutritional replacement with castor cake under different irrigation depths. The experiment was conducted in two periods: June 29 to September 30 of 2009 and May 7 to August 3 of 2010. The water consumption of potato for the inference of crop coefficients (kc's) was quantified only in the year 2010, which were 0.35, 045, 1.29 and 0.63. In the same period of cultivation, due to simulate the evapotranspiration of culture with kc's recommended by the FAO, it would become excessive, with a overestimate by 32,6 mm. For both growing seasons, no significant changes in the parameters of the tuber yield of potatoes under irrigation depths applied were found. Fertilization with castor cake was responsible for the increase by 18% and 19% of the total and commercial tuber, respectively. For the year 2009, the average total yield for the two fertilization conditions were 13.9 and 16.31 ton ha-1 respectively in the absence and presence of castor cake. For 2010, the average yield was 10 ton ha-1, with the level of TM. The expression of the efficiency of water use was: y = 0.0435 x ² - 9.0182 x + 557.12, where x irrigation depth (mm) and y the yield (kg ha-1). The following conclusions were: the quantification of local water demand of potato can provide savings of 30% of water application; fertilization with castor cake is promising to achieve higher productivity of tubers;. the depths of irrigation can extend the cycle of potato; the Opaline cultivar proved to be productive under low and high levels of water supply; it´s necessary more studies about the recommended planting dates of potato, to the soil and climate conditions of Seropedica-RJ.