High temperatures significantly affect rice grain yield and quality. However, little information is known about the response of indica cultivars, especially Vietnamese cultivars, to high temperature. In this study, field experiments were conducted in 2015 and 2016 to evaluate the response of Vietnamese cultivars under high temperatures during the grain filling period. The high temperature was applied after the first cultivar started anthesis, by opening two sides of a plastic chamber that housed the cultivar when the temperature reached above 36 • C under field conditions. The difference in the maximum temperature between the control and the high temperature treatment was about 1.3 • C to 10.1 • C in 2015, and 0.73 • C to 10.2 • C in 2016. Decreases in crop growth rate (CGR) and yield were correlated with increased temperature conditions during the grain filling period. The grain yield of 14 Vietnamese cultivars fell to 81.5 and 79.4% of the control in 2015 and 2016, respectively. The variable with the greatest impact on grain yield was spikelet sterility induced by high temperature. Under high temperature conditions during the grain filling period, the percentage of grain chalkiness in the high temperature-treatment group increased compared to the control. Our study showed that Vietnamese rice yield and quality were significantly affected by high temperature.

Abstract:Chili peppers grow best and are likely to reach the maximum yield at temperature ranging from 21 °C to 33 °C. In the plastic house, the temperature increases to 42 °C in the summer. The fruit set and fruit growth were effected correlative with the high temperature condition. In this study, Shishito peppers were grown in plastic house in two periods (in the early stage of April and the end stage of May) in 2012. The difference in temperature between two periods of planting was about 4 °C. In fruit set period of the 2nd planting, the weather condition is disadvantage for fruit growth. During temperature changed in the summer, the fruit weight and the number of seeds per fruit of both "Shishi-homare" and 105c-10 varieties were reduced about 0.5 and 2.8 times in the 2nd planting when compared with the 1st planting. The number of seeds per fruit reduced corresponding with the fruit size under the high temperature condition.

Environmental stress trigger a variety of rice plant response, ranging from alters seed set, grain yield and grain quality during flowering and grain filling stage.  Efforts are required to improve our understanding of the impact of heat stress on rice production, which are essential strategies in rice cultivation. This article investigated the seed set, yield components and grain yield of Vietnamese rice cultivars (Indica germplasm) under high temperature environment during the flowering and grain filling stage. Six rice cultivars, including popular cultivars and new cultivars of Cuu Long Delta Rice Research Institute, and one popular extraneous cultivar with differences in maturing time, were grown in pots at high temperature (HT) and natural temperature condition as control (CT). All rice cultivars were subjected to the high temperature starting from the heading stage to the harvest maturity, applied by greenhouse effect. The greenhouse has about 25 cm window opening on 3 sides for air ventilation. The seed set rate of the heat-sensitive rice genotypes decreased significantly under HT, leading to a significant reduction in grain yield. The lowest seed set was recorded in “OM4900” (44.3%) and “OM18” (39.9%) under high temperature environment. The lower yield in all rice cultivars at an elevated temperature resulted in a dramatic decrease of filled grains and contributed to a loss of 1000-grain weight. ‘“OM892” is a potential rice cultivar for heat tolerant breeding program due to the seed set percentage was above 80% in both HT and CT conditions. High temperature during the grain filling stage resulted in a decreased amylose and increased chalkiness for all OM cultivars.