Evaluation of Usefulness of Daily Mean Temperature Studies on Impact of Climate Change

The impact of global warming on rise in temperature in different regions has often been expressed as a change in mean temperature (T_mean). The recent results suggest that this change could be both in diurnal and interannual temperatures. Therefore it is important to assess the impact of diurnal variation with the same mean temperature on crop plants for understanding the impact of climate change on agriculture, and also assess the possibility of genetic variation in adaptation. The present study in wheat (Triticum aestivum) varieties examines the effect of varying T_max and T_min, while maintaining the same mean temperature on phenology, growth and productivity. The mean temperatures examined are 18 °C with T_max/T_min combination of 18/18, 20/16, 22/14 and 24/12 °C. These wheat varieties differed considerably in their response to varying T_max and T_min with respect to days to ear emergence, anthesis, biomass accumulation and grain yield. The wheat variety HD2329, a popular Mexican dwarf high yielding cultivar showed maximum adaptation in the temperature combinations examined. The results suggest the need to refine the crop ideotypes in the context of the changing global scenario. This may require detailed experimental studies on various phenological phases. Such studies would help in assessing genotypes which may be having adaptation and thus identify the potential donors for further improvement of crops.