|Gesch, Russell - Russ|
|ALLEN JR, L|
Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 11/9/2000
Publication Date: N/A
Technical Abstract: The growth and yield processes of rice under projected global warming conditions were evaluated so as to determine climatic limitations to yield. Two rice cultivars of contrasting climatic origin, IR-72 (tropical, indica type) and M-103 (temperate, japonica type) were grown under two levels of CO2 (350 and 700 uL L**-1) at five diurnal temperature cycles (40/30, 37/27, 34/24, 31/21 and 28/18 degrees Celsius). The indica type being from tropical regions, was hypothesized to be more tolerant of high temperature. Yield declined with increasing temperature, an effect attributed to the shortening of life cycle, lower biomass accumulation, a decrease in panicle number, fewer filled spikelets and shorter grain filling duration. Yield failures at the highest temperature were attributed to spikelet sterility as filled grain percentages were near zero. CO2 enrichment had no significant effect on yield despite a stimulatory effect on biomass accumulation and tillering. Significant temperature by cultivar interactions and higher temperature optimums of 1 to 4 degrees Celsius for IR-72 were observed for several vegetative and reproductive characteristics. Considerable intraspecific variability in response to temperature exists between the two cultivars although both ecotypes failed equally at the highest temperature.