Grain yield and quality of irrigated rice in seasons with different thermal regimes at flowering

Abstract

Temperature is one of the most important climatic factors for rice production. Temperatures above 35ºC limit the production of this cereal, damaging irreversibly its yield. Anthesis is the most sensitive phase of rice to the occurrence of high temperatures. This experiment was carried out aiming to evaluate the agronomic performance and grain quality of five rice genotypes (Epagri 109, SCS116 Satoru, SCS121 CL, SCS122 Miura and SC 676) at two growing seasons (2016/17 and 2017/18), correlating them with the air temperature during anthesis and grain filling. The following variables were assessed: spikelet sterility, yield, mass of 1,000 grains and postharvest qualitative aspects (milling yield and chalky grain percentage). The temperatures recorded in the 2016/17 growing season from anthesis to harvest were higher than in 2017/18. They present averages of 30.5 and 28.5ºC and maximum temperatures of 34.3 and 30.9ºC for each experimental year, respectively. The higher temperatures of the first growing season reduced grain yield, 1,000 grain mass and milling yield. They also increased spikelet sterility and chalky grains. The inbreed line SC 676 presented the highest yield (13,070kg ha^-1), however, it was also the genotype with worst grain quality.