Restrição de radiação solar na produtividade de arroz irrigado

Abstract

Rice (Oryza sativa L.) yield potential is defined by the availability of solar radiation during the growing season. The reduction of solar radiation pointed out by future climate change scenarios and in “El Niño” years in Southern Brazil can reduce crop yield. The objectives of this study are to indicate at which development phase the productivity is most penalized as a result of solar radiation restriction, and to estimate how much the crop fails to produce on a cloudy day at each development phase. Were used screens with 24%, 36% and 43% restriction intensity of incident solar radiation at vegetative, reproductive and grain filling phases besides a control treatment with 0% solar radiation restriction. The field experiments were conducted at 4 sites (Cachoeirinha, Santa Maria, Agudo e Itaqui) during the growing seasons 2017/18 e 2018/19 in Rio Grande do Sul, Brazil. We identified that the penalty on productivity as a result of solar radiation restriction is more intense during grain filling (142,1 kg ha-1dia-1), followed by the reproductive phase (126,1 kg ha-1dia-1) and vegetative phase (28,1 kg ha-1dia-1). These results are important to optimize the sowing date management and to direct genetic improvement programs in the search for more efficient cultivars in the solar radiation use.