Tuesday, November 14, 2006 - 9:45 AM

Effects of high nighttime temperature on rice (Oryza sativa L.) growth, development and physiology.

Abdul-razack Mohammed, Elliott W. Rounds, and Lee Tarpley. Texas A&M University, Dept of Soils & Crop Sciences, College Station, TX 77843

Periodic episodes of heat stress are predicted to occur more frequently in this changing weather environment. These events could exacerbate climate change effects on many aspects of crop growth and development, reducing crop yield and affecting crop quality. The presence of seasonally high nighttime temperatures along the Gulf Coast, occurring during the critical stages of development, could reduce rice yield and quality. The objective of this study was to determine the effects of high nighttime temperature on growth, development and morphology of rice plants. Plants were grown under ambient (average of 27 oC) and elevated nighttime temperatures (32 oC) in the greenhouse. They were subjected to an elevated nighttime temperature through use of infrared heaters. Air temperatures were controlled at predetermined set points. When the temperature was below the set point, infrared heaters provided short pulses of heat, as needed, to raise the temperature to the desired set point. Air temperatures were monitored and maintained within the set points ± 0.5 oC. The high nighttime temperature was applied from 2000h until 0600h. Our results indicate significant increase in height, leaf number and leaf area for plants grown under high nighttime temperature. There were no significant differences between the control and the heat treatment with respect to stem length, culm length, number of tillers and number of panicles. Plants grown under elevated nighttime temperature showed a significant increase in stem and leaf dry weight, when compared to the control plants.  Our results indicated no change in the time interval between emergence and panicle initiation under high nighttime temperature. However, there was a significant decrease in rice yields for plants grown under high nighttime temperature. Partially supported by the Texas Rice Belt Warehouse and Texas Rice Research Foundation.