Energy balance and evapotranspiration of melon grown with plastic mulch in the Brazilian semiarid region

Valéria Peixoto Borges, Bernardo Barbosa da Silva, José Espínola Sobrinho, Rafael da Costa Ferreira, Alexsandra Duarte de Oliveira, José Francismar de Medeiros
2015 Scientia Agricola  
Melon plants (Cucumis melo L.) are grown in the state of Rio Grande do Norte (RN), the largest producer of melons in Brazil, with plastic mulch and agrotextiles. Studies of crop evapotranspiration (ET) under these conditions are required to ensure adequate irrigation. This study aimed to determine the crop coefficients (Kc) of irrigated melon plants grown with mulch and agrotextiles in the region of Mossoró, RN, based on the Bowen Ratio Energy Balance (BREB) method. Two experiments were
more » ... iments were conducted at different times during the 2009/2010 season in a melon producing area (4°59'52" S, 37°23'09" W, and 54 m elevation) to define ET and Kc. Due to the plastic cover and reduced precipitation during the experiments, the Kc obtained by the BREB method was considered the basal Kc -Kcb BREB . The results were compared with the Kcb from the FAO 56 Bulletin. There was close agreement between BREB and FAO ET measurements (12 % underestimation by the FAO method for the entire crop season), with sizeable differences only during the initial phenological stage. The mean Kcb BREB values of the two field campaigns were 0.26, 0.96 and 0.63 for the initial, midseason and late stages, respectively. The high Kcb BREB value in the initial growth phase may be related to the effect of the plastic mulch and agrotextiles on the energy balance at the surface. The relationship between Kcb BREB and fc had high correlation, making possible an estimation of the melon Kcb based on the level of crop ground cover. been obtained under different conditions (Campos et al., 2010; Inman-Bamber and McGlinchey, 2003; Lovelli et al., 2005). Melon production in Mossoró involves specific practices; therefore, local studies are important for providing information regarding the efficient use of water. Methods for obtaining evapotranspiration based on energy balance are potentially interesting for analyzing the impact of crop management practices on energy fluxes and, thus, the loss of water from the plant surface. Among the methods for estimating ET based on energy balance, the Bowen Ratio Energy Balance (BREB) has been well evaluated and is recommended by several authors for different crops (Irmak, et al., 2013; Hou et al., 2010; Zhang et al., 2010; Zeggaf et al., 2008) . This study applied the BREB method to determine the crop coefficients of irrigated melon grown with plastic mulch and agrotextiles in the region of Mossoró, state of Rio Grande do Norte, Brazil, to provide more locally appropriate information to irrigators to maintain high yields with more efficient use of water. Materials and Methods Characteristics of the experimental site and crop practices Two field experiments were conducted in a melonproducing field in the municipality of Mossoró, in the
doi:10.1590/0103-9016-2014-0136 fatcat:czbk75sccbfbrl7yksrq7nrhs4