Effects of high night temperature on yield and agronomic traits of irrigated rice under field chamber system condition

摘要

Temperature during night is greater than daytime and tends to be further increased in the future as a result of global warming. However, little information is known about genotypic responses to warm nighttime temperatures in situ. Field experiments were conducted in 2009 wet season (WS), 2010 dry season (DS), 2010WS and 2011DS at IRRI to determine the genotypic variation in sensitivity to warm nighttime temperature. Thirty-six varieties, originated from different countries, were grown in temperature-controlled field chambers. An increase of 4.8 °C, 4.0 °C, 3.9 °C and 3.8 °C in night temperature was imposed on the plants from 40 to 120 days after transplanting (DAT) from 1900h to 0600h. Significant difference of grain yield between low night temperature (LNT) and high night temperature (HNT) treatment was observed in all experiments. Grain yield in HNT was decreased by 16.7, 9.1, 9.6 and 8.0 than LNT in the four consecutive seasons, respectively. The negative effect of HNT on grain yield was partially due to low biomass and low harvest index (HI). Plants in LNT achieved higher total dry weight because of higher crop growth rate (CGR). Mild increase in night temperature during the reproductive growth stage reduced yield which was attributed to decrease in grain weight, harvest index, grain filling (2009WS), and spikelets number per panicle (2010DS and 2011DS). Our study showed that ~4°C differences between HNT and LNT in the field chamber system causes 11 grain yield decrease on average of four consecutive seasons. Genotypes N22, PSBRc52, Swarna and IR8 were tolerant to high night temperature.