Spikelets Fertility and Quality of Local Upland Rice (Oryza sativa L.) Seeds Due to High Temperature at Various Stages

Stress from high temperatures is one of the factors that restrict rice plant growth and development. Rice generative stage sensitivity to high temperatures is well established, but its vegetative stage sensitivity is more uncertain. To identify high-temperature tolerance traits in the vegetative and generative stages, four local upland rice genotypes were tested under high-temperature stress treatment (32-36°C) during the vegetative stage, generative stage and vegetative-generative stage and ambient temperature (27-31°C) during the vegetative-generative stage as a control. The research used a nested randomized block design (RAK) and was repeated in 3 repetitions. SPSS Ver. 20 program was used to analyze the data. The results showed that under stress from high temperature both thegenerative stage and the vegetative-generative stage significantly reduced the quantity of pollen germinated in all genotypes. The application of under stress from the high temperature in the generative stage showed a serious impact on panicle length, spikelets in each panicle, spikelet fertility in each panicle, weight of filled grain in each panicle, weight of 1000 grains and reduction in amylose compared to theunder stress from high temperature both in the vegetative and vegetative-generative stages. In contrast to previous research, the impact of high temperatures in the vegetative stage was able to significantly increase the length of the panicle, quantity of spikelets in each panicle, spikelet fertility in each panicle, weight of filled grain in each panicle and weight of 1000 grains. The Bangkok genotype has a quantity of pollen germinated of 61.21-44.64%, spikelet fertility in each panicle of 74.91-215.52 grains andweight of filled grain in each panicle of 1.43-4.88 g higher as well as a decrease in amylose and an increase in protein lower than the other three genotypes at high-temperature stress at various stage stages, the Bengkok genotype is a potential genetic source for increasing tolerance to under stress from high temperature in the vegetative and generative stages.