Temperature thresholds and crop production: a review

Abstract

Temperature thresholds for a range of crops from cereal crops to horticultural crops and to legum crops were identified through an extensive literature review. Identification of temperature thresholds provides a basis for quantifying the probability of exceeding temperature thresholds which is a very important aspect of climate change risk assessment. The effects of extreme temperatures on yield and yield components were then reviewed and summarised. Through these processes, critical phenophases were defined based on the sensitivity of crop yield and/or yield components to extreme high temperatures which were imposed on various phenophases. Information on the direction and degree of the impact of extreme temperature on yield/yield components can contribute to the improvement of crop models in which the effects of extreme temperature on crop production have not been adequately represented at this stage. Identification of critical phenophases at which crops yield and/or other economic characteristics are sensitive to extreme temperatures will help scoping appropriate adaptation options.

Early heat waves over Italy and their impacts on durum wheat yields

“…These studies substantially agree on the strong effect of extreme temperatures in the reduction of final yields. However, the magnitude of reduction, the mechanism of the effects of extreme temperature on crops and the identification of temperature thresholds at different crop growing stages are still under debate (Luo, 2011).…”

“…It is worth highlighting that other factors can act in modulating and changing the effect of heat waves, such as the combination of heat wave and drought as productivity of wheat is reduced considerably when combined stress is applied (Barnabás et al, 2008). A specific evaluation of the effects of early heat waves on pre-and/or post-anthesis phases should be tested as a next step (retrieving metadata on phenological phases), considering that recent studies (Luo, 2011) have highlighted the effects of high temperature imposed at pre-anthesis phase being greater than the ones imposed at post-anthesis.…”

Effects of heat extremes on wheat yields in Australia

“…2002RT , 1980, 1969RT , 1914R , 2010RT , 1977, 1983, 1972RT , 1979, 1963. 2003, 2011, 1999R , 1997, 2005, 1998, 1993, 1995, 1996, 2001 Supplementary Table 6: Correlations between the number of heat-days and wheat yields, in each month and annually, once the effect of rainfall is removed, using de-trended wheat data for the two wheat regions defined in Figure 1, calculated over the 1911-2012 period. The 'Contemporaneous' correlations use rainfall totals from only the month in the accumulation, whereas the 'Cumulative' correlations use rainfall totals from the 12 months up-to-and-including the month stated in the accumulation period.…”

“…Barlow et al (2013) and Alexander et al (2010) suggest that 35°C is an appropriate threshold, whilst Luo (2011) finds that temperatures above 32.7 o C during the period of sowing to emergence, and 35.2 o C for grain filling (the growth stage where carbohydrates and protein stores increase within the grain), are detrimental to wheat. Asseng et al (2011) and Lobell et al (2012) both use a 34 o C threshold, with Asseng et al (2011) finding that this temperature corresponds to a 50 per cent reduction in wheat yields.…”

Response of maize and olive to climate change under the semi-arid conditions of southern Spain

“…In the Iberian Peninsula, the heat extreme events represent a threat to summer-grown but not to winter-grown crops . The term "heat stress" on plants under these extreme temperature events has been used to refer to brief episodes of high temperature lying outside of the range typically experienced (Porter and Gawith, 1999;Luo, 2011;.…”