By Michael Dingkuhn
IRRI-CIRAD crop physiologist
Thursday, 17 January 2013
Havener Auditorium, IRRI
(By Michael Dingkuhn, Cecile Julia, Jean-Christophe Soulie, Richard Pasco, and Uttam Kumar)
The general environmental adaptation of plant genotypes is in a large part related to response to temperature and to closely related variables such as humidity. Phenology and morphogenetic processes are driven by these. They directly contribute to yield potential. Thermal stresses reduce yield and occur when key processes are disrupted during periods of extreme temperature.
The first part of presentation is about evidence that crop-generated microclimate, in conjunction with genotypic escape and avoidance mechanisms, are extremely effective in rice. In fact, accurate predictions of thermal response are impossible on the basis of weather data alone because the temperature of sensitive organs may deviate by 10°C from ambient temperature due to transpiration cooling and canopy architecture.
Furthermore, the time of day of sensitive physiological processes shows adaptive plasticity. One consequence is that heat sterility is possibly more prevalent in warm-humid climates than in extremely hot but dry climates. Another is that water-saving irrigation in hot-dry systems must be considered with great caution. We conclude that crop models must consider microclimate to avoid misleading global and regional assessments.
The second part presents RIDEV, a microclimate-based model of phenology and thermal sterility in rice. The model is being used in forward mode (predictive) for agronomic and agro-ecological applications, and in reverse mode (heuristic) for phenomics in a genomics research context.
RIDEV is now being used in (1) GRiSP-CCAFS climate change adaptation research, (2) agronomic applications with AfricaRice, and (3) the GRiSP Global Phenotyping Network.
More research and model improvement is needed with respect to water-saving irrigation against microclimate, temperature-drought interactions, effects of ambient CO2 on microclimate and the genetics of heat escape and avoidance traits.