Eficiência do uso da radiação solar em arroz de terras baixas irrigado por aspersão

Abstract

The objective of this study was to determine the efficiency of the use of solar radiation (EUR) in lowland rice cultivars with different sprinkler irrigation layers. Three experiments were carried out in the field, on the experimental area of the Federal University of Pampa, in the growing seasons 2014/2015, 2015/2016 and 2016/2017. In the first year (2014/2015) the treatments were composed by three lowland rice (XP 102, IRGA 428 and IRGA 429), five irrigation layers, 0, 50, 100 and 150 and 200% of crop evapotranspiration (ETc), with four replications. In the second year, treatments were composed by three lowland rice cultivars (BR IRGA 409, IRGA 428 and IRGA 424), five irrigation layers (0, 50, 100, 150 and 200%) with four replications. In the third growing season, the treatment was composed by the IRGA 424 RI irrigated by five layers (50, 100, 150, 200 and 250% of Etc) and four replications. To determine the grain yield and the shoot dry mass (SDM) was obtained with two samples of 0.25 m², 0.5 m² total, when the plants were at physiological maturity (R9). A EUR for grain yield was obtained by the equation, grain yield = EUR /K↓. Already EUR to AGDM was obtained by be equation AGDM /K↓. ANOVA was performed by the software SISVAR and statistical analysis and graphs were performed in SIGMAPLOT 10.0. The largest SDM values and grain yield were found in the agricultural year 2014/2015, and consequently higher EUR, followed by the agricultural year 2016/2017. The year 2015/2016 was hampered due to the El Niño Strong occurred in the cultivation period. In most treatments, grain yield EUR followed a logistic behavior, having a tendency to stabilize on the 150% ETc irrgation layer. Already the SDM EUR presented linear behavior, with the exception of the agricultural year 2014/2015. From this study, it can be verified that the removal of the water slide on the soil surface changes the EUR for grain yield and SDM. The lowland rice cultivars tested are adapted to the sprinkler irrigation system, and the slides of 150, 200 and 250% of ETc reach EUR values close to that of the flood irrigation system.