Evapotranspiração da cultura do milho (Zea mays L.) com rede de cobertura e sem cobertura a várias densidades de plantio

Abstract

In the southern region of Mozambique, the low water availability and the limiting factor for the growth and yield of the corn crop due to low rainfall, high radiation and high evatranspiration, often causing significant reductions in the yields of this crop. Thus, studies aimed at determining the water needs of the crop are important for recommending alternative technologies in order to minimize the problem. In order to determine the average evapotranspiration of the corn crop (ETm), during the crop development cycle, this work was developed, consisting of two tests carried out, taking into account the factors covering and planting density, consisting of a planting at open skies and 41% attenuation coverage network and five densities of three repetitions each, namely: 2500pls / ha- (D1), 28125 pls / ha- (D2), 3750pls / ha (D3), 53125pls / ha- ( D4), 84375pls / ha- (D5). The work was carried out at the agrarian station of Umbelúzi, district of Boane, located 25 km from the city of Maputo (latitude: 26º02 ’, longitude: 32º18’ and altitude: 12m), during the period 2003/2004. The culture used was Matuba, a variety recommended by I.N.I.A for the southern zone. Some microclimate parameters were analyzed, such as temperature, radiation, wind, humidity, vapor tension and other important parameters for the determination of evapotranspiration, such as stomatal resistance and leaf area index. The average evopotranspiration of the culture was determined using the Penman-Monteith and Richie-Burnett methods. The accumulated ETm obtained for each density during the cycle (sowing to physiological maturation), inside the greenhouse was 11.38mm- (D1), 13.35mm- (D2), 16.84mm- (D3), 17.95mm- (D4) and 24.78mm- (D5), while outside the net it was 24.90mm- (D1), 25.33mm- (D2), 30.63mm- (D3), 34.93mm- (D4) and 46.45mm- (D5). The subperiod where the highest average daily evapotranspiration rate was found was between the weighing and the milky maturation (October-November), having been recorded in October (4.74mm / day) outside the greenhouse and October (2.64mm / day) ) inside the greenhouse, while November (6.38mm / day), and November (3.33mm / day) respectively and the maximum ETm occurred 84 days after planting (6.38mm / day).