Abstract
Abstract Limited-transpiration rate at high evaporative demand (‘LTR’ trait) has potential to improve drought adaptation, crop water productivity and food security. The quantification of the implications of LTR for water consumption, biomass accumulation and yield formation requires the use of dynamic crop modelling to simulate physiological and environmental processes and interactions in target environments. Here, a new transpiration module was developed for the Agricultural Production Systems sIMulator (APSIM NextGen) and used to simulate atmospheric and edaphic water stress on wheat crops. This module was parameterized with (i) data from a lysimeter experiment assessing genotypic variability in the LTR trait for four genotypes contrasting in transpiration efficiency, and with (ii) a more pronounced response to high evaporative demand. The potential of the LTR trait for improving crop productivity was investigated across the Australian wheatbelt over 1989–2018. The LTR trait was simulated to allow an increase in national yield by up to 2.6 %, mostly due to shift in water use pattern, alleviation of water deficit during grain filling period and a higher harvest index. Greatest productivity gains were found in the north-east (4.9 %, on average) where heavy soils allow the conserved water with the LTR trait to be available later at more critical stages. The effect of the LTR trait on yield was enhanced under the future climate scenario, particularly in the north-east. Limiting transpiration at high evaporative demands appears to be a promising trait for selection by breeders, especially in drought-prone environments where crops heavily rely on stored soil moisture.
Highlights
40 % of the world’s food supply is provided by wheat crops (FAO 2013)
This may be due to the fact that the vapour pressure deficit (VPD) breakpoint identified when using weeks of data recorded at 10-min intervals was typically significantly lower (1.3 kPa) than in experiments carried out with far fewer measurements done (i) over short periods at controlled VPD levels or (ii) over 2 days at 1-h interval in fluctuating VPD
Significant genotypic variations in transpiration efficiency (TE) were found among the four studied Australian commercial cultivars that were associated with different levels of expression of the limited transpiration (LTR) trait
Summary
40 % of the world’s food supply is provided by wheat crops (FAO 2013). A common challenge faced by wheat growers and breeders is the lack of soil moisture available for the plant, which often limits crop production (Araus et al 2002). In Australian rain-fed production regions, drought is a major factor limiting wheat production (e.g. Murphy and Timbal 2008; Chenu et al 2011, 2013; Rebetzke et al 2013). High temperature is increasingly impacting wheat productivity due to suboptimal temperature (Zheng et al 2016; Hunt et al 2018; Ababaei and Chenu 2020) and its impact on evaporative demand (Lobell et al 2013). Drought and heat-shocks are expected to remain major issues if no adaptation is considered (Lobell et al 2015; Watson et al 2017; Webber et al 2018, 2020; Ababaei and Najeeb 2020)
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