Requerimento de água e coeficiente de cultivo de três cultivares de grão-de-bico em condições climáticas controladas

Abstract

The chickpea (Cicer arietinum L.) has potential for cultivation in regions of the Brazilian Cerrado (a kind of Savannah) intended both to supply the domestic market and to export, generating economic and social benefits for the agro-livestock sector. This study aimed to measure water demand and determine the cultivation coefficient of three chickpea cultivars, grown under irrigation in the Brazilian Midwest region. The experiment was carried out in a greenhouse at the School of Agronomy at the Federal University of Goiás, Goiás State, Brazil. Seeds of three chickpea cultivars (BRS Aleppo, BRS Cristalino, and Cícero) were used, sown directly in 8 L volume pots. Irrigation was done by automatically dripping, considering the readings of capacitive soil moisture sensors. The meteorological data was acquired by a metrological station installed inside the greenhouse. The calculation of the reference evapotranspiration (ETo) was carried out in accordance with the equation proposed by Penman-Monteith; the culture evapotranspiration (ETc) was estimated by weighing the lysimeter, and the culture coefficient (Kc) was estimated considering the relationship between culture evapotranspiration and reference evapotranspiration. The average reference evapotranspiration was 5.8 mm day-1. The seasonal needs for water consumption were 518.7 mm, 474.7 mm, and 506.6 mm day-1 for the cultivars Cícero, BRS Aleppo, and BRS Cristalino, respectively. The culture cycle was separated into four phases: (a) phase I comprising the initial culture period, ranging from 13 to 19 days after planting; (b) phase II was the phase reached from the 40th to the 52nd day after planting; (c) phase III was the phase reached from the 89th to the 91st day after planting; and (d) phase IV was the culture final phase. The peak of evapotranspiration was reached in phase III due to the greater metabolic activity for flowering and graining. In phase I, the average ETc was 2.2 mm, 2.3 mm, and 2.2 mm day-1; in phase II, it was 3.9 mm, 3.8 mm, and 3.2 mm day-1; and, in phase III, it was 5.6 mm, 4.6 mm, and 5.4 mm dia-1 for Cícero, BRS Aleppo, and BRS Cristalino, respectively. In phase IV, the cultivars showed an average ETc of 4.8 mm and 4.7 mm day-1, respectively, for Cícero and BRS Cristalino, whereas the cultivar BRS Allepo has not been included in phase IV during the analysis period. Different patterns of Kc evolution were found among the three cultivars and the condition presented by Food and Agriculture Organization (FAO). The average chickpea ETc throughout the cycle was 4.5 mm, 4.1 mm, and 4.5 mm day-1 for the cultivars Cícero, BRS Aleppo, and BRS Cristalino, respectively. The Kc values for Cicero were 0.38 mm, 1.00 mm, and 0.75 mm day-1 for phase I, III, and IV, respectively. For BRS Aleppo, the values were 0.39 mm day-1 in phase I, and 0.80 mm day-1 in phase III. BRS Cristalino cultivar showed Kc values of 0.39 mm, 0.95 mm, and 0.65 mm day-1 in phase I, III, and IV, respectively.