Temperatures and the growth and development of wheat: a review

We start by outlining the general effects of climatic variability and tempe rature extremes on wheat yields in the context of extreme event effects on crop processes for climatic impacts studies. We then review literature desc ribing the responses of wheat plants to extreme temperatures. Cardinal temp erature thresholds for different phenological processes in wheat are identi fied and we outline the effects of temperature on rates of growth and devel opment. Finally, we assess the implications of the above for future climati c impact studies. Our summary shows how relatively small and consistent are the standard erro rs of the cardinal mean temperatures for many of the processes examined. Ca rdinal temperatures are conservative between studies and are seemingly well -defined in wheat. Into this category we put the lethal limits for wheat, t he sterility response at anthesis, the cardinal temperatures for vernalizat ion and some of the base and optimal temperatures. Important questions for the future involve the effects of combinations of extreme events and the mo delling of specific effects such as the influence of high temperatures on g rain set. (C) 1999 Elsevier Science B.V. All rights reserved.