Consumo hídrico da cultura do girassol irrigada na região da chapada do Apodi-RN.

Abstract

Data of field experiment conducted in the Empresa de Pesquisa Agropecuária do Rio Grande do Norte – EMPARN, located in the borough of Apodi – RN for determining the water use of the san-flower crop grown in the climatic conditions of the Apodi-Rn region, for each phenological phase and for the whole grown cycle. For that, Penman-Monteith, Bowen-ratio energy balance and the rate of crop to reference evapotrnspiration were used to estimates ETo, ETp and Kc, respectively. The experiment was conducted in an experimental plot of 1.01 ha grown with sun-flower, cultivar Catissol with 40,000 plants per hectare, approximately. The crop was irrigated by a sprinkler irrigation system, considering an irrigation efficiency of 75% given a total irrigation depth of 624.4 mm for the crop growing cycle. On the average, the components of the energy balance were distributed as 86,5% for latent heat flux (LE), 8.9% for sensible heat flux and 4.6% for soil heat flux. The sun-flower growing cycle was completed in 91 days being 16, 25, 25 and 25 days for the initial (phase I), vegetative development (phase II), flowing (phase III) and physiological maturation (phase IV), respectively. The average daily evapotranspiration for each phonological phase and the water use for the whole crop growing cycle were 4.3, 6.8,6.7, 5.9 mm day-1 and 626.5 mm, respectively. The crop coefficient showed mean values of 0.61, 0.87, 0.83 and 0.77 for the initial, vegetative development, flowing and phenological maturation phases, respectively.