Abstract
Nighttime warming poses a threat to global food security as it is driving yield declines worldwide, but our understanding of the physiological basis of this phenomenon remains very limited. Furthermore, it is often assumed that such declines are driven solely by increases in nighttime temperature (TNight). Here we argue that, in addition to temperature, increases in nighttime evaporative demand may 'conspire' to penalize yields and end-use quality traits. We propose an ecophysiological framework outlining the possible mechanistic basis of such declines in yield and quality. We suggest ways to use the proposed framework as a guide to future efforts aimed at alleviating productivity losses by integrating crop ecophysiology with modeling, breeding, and management.
Highlights
This phenomenon is more complex than may be assumed, likely to involve interaction between two driving forces: nighttime temperature and evaporative demand
In grapevine (Vitis vinifera), for instance, increasing TNight from 25°C to 35°C resulted in increased leaf respiratory carbon losses reflected by decreases in nonstructural carbohydrates by 0.025 and 0.041 mg g−1 dry weight, respectively, relative to the control treatment of 15°C [40]. Such losses are consistent with metabolite profiling studies in wheat and rice, which revealed an increase in tricarboxylic acid (TCA) cycle intermediates in leaves exposed to high TNight, supporting increased respiration in the photosynthesizing tissue [36,41]
This could be achieved by integrating crop physiology with crop modeling, breeding, end-use requirements, and cropping system management, along four research domains detailed in the Outstanding Questions
Summary
Nighttime warming poses a threat to global food security as it is driving yield declines worldwide, but our understanding of the physiological basis of this phenomenon remains very limited. An overwhelming majority of reports have shown that heat stress due to increases in temperature are driving global yield declines of major crops more than any other environmental stressors [2,3,4,5] This has resulted in major international efforts to better understand the mechanisms of heat stress in crops and initiate global initiatives to mitigate its negative effects on crop productivity (e.g., see reviews in [6,7]). Nighttime warming is reducing crop yields worldwide, threatening global food security This phenomenon is more complex than may be assumed, likely to involve interaction between two driving forces: nighttime temperature and evaporative demand. An ecophysiological framework is proposed as a guide to implement future research efforts to mitigate yield declines Such efforts should integrate physiology with crop modeling, breeding, and management to identify sustainable pathways for mitigation as climate change intensifies. About 4–7% reduction in yield per 1°C increase in TNight was observed for field-grown spring wheat and rice, with treatments imposed during flowering and seed-fill stages [13,14,18]
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