Limiting transpiration rate in high evaporative demand conditions to improve Australian wheat productivity

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 parameterised 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 northeast (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 northeast. 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.

A robust field-based method to screen heat tolerance in wheat

“…These extreme heat events have substantially affected the growth, development and ultimately, yield of wheat crops (e.g. Collins et al, 2021; Collins and Chenu, 2021; Zheng et al, 2016). With the recent rate of climate change, a further increase in the frequency of these heat events is projected in the near future both in Australia (Ababaei and Chenu, 2020) and globally (Field et al, 2012).…”

Modifying root/shoot ratios improves root water influxes in wheat under drought stress

“…Transpiration efficiency (TE) is a key adaptive trait under semi-arid conditions (Collins et al, 2021) that can be regulated by the stomatal response to water stress and environmental state. In WW treatment both genotypes exhibited similar gsc before VPD reached its peak (i.e., mid-day); under TD, IL20 exhibited greater gsc early in the morning (07:00-10:00 AM) compared with Svevo (Fig.…”

“…Under semi-arid conditions, transpiration efficiency (TE) is a key adaptive trait (Collins et al, 2021), that can be mediated by stomatal responsiveness to environmental cues. For example, maximizing the transpiration rate under a preferable atmospheric state has been suggested as a breeding target for drought-prone maize (Zea mays) agro-system (Messina et al, 2015).…”

Physiological and Genetic Drivers Underpinning Canopy Development are Associated with Durum Wheat Yield in Rainfed Environments

“…For instance, changes in canopy development (e.g., reduction in leaf size or tillering) provide an advantage under terminal drought conditions by shifting water use from pre-to post-anthesis (Borrell et al, 2014; George-Jaeggli, Mortlock, & Borrell, 2017). Limited transpiration rate at high evaporative demand can also conserve water for critical stages later in crop development (Collins, Chapman, Hammer, & Chenu, 2021). There is a fine balance between water supply and demand in crops and as such, the timing of water availability must be matched with phenological development.…”

“…Although rapid canopy development can increase light interception (Regan, Siddique, Tennant, & Abrecht, 1997) and reduce soil evaporation (Lopez-Castaneda, Richards, & Farquhar, 1995), if there is insufficient stored soil moisture or in-crop rainfall, excessive canopy size may prematurely deplete soil water and exacerbate terminal drought (Nuttall et al, 2012). Thus, crop performance under drought conditions depends on complex source-sink dynamics between carbohydrate and water balance, where there are trade-offs between stress resilience and yield (Collins et al, 2021; Rodrigues, Inze, Nelissen, & Saibo, 2019). Given the dynamic nature of the environment, understanding canopy development may help to identify integrative traits that support yield.…”