Night Temperature Determines Nearly Half of Wheat Yield Variation Globally

Why It Matters

Warmer nights threaten wheat’s productivity, jeopardizing a staple that supplies 20% of global calories and protein, and underscore the urgency for climate‑resilient breeding and agronomic strategies.

Key Takeaways

• Nighttime temperature rise cuts wheat yield by ~0.5 t/ha per °C
• Average Tmin during grain filling explains 40% of global yield variance
• A 1.2 °C rise across sites drops yields over 10%
• Shorter grain‑filling periods and higher night respiration drive losses
• Adapting wheat to warmer nights could boost global production

Pulse Analysis

Nighttime temperatures are climbing faster than daytime highs, a trend that has slipped under the radar of most crop‑climate research. Wheat, the world’s most widely cultivated cereal, occupies over 220 million hectares and underpins one‑fifth of human nutrition. As global warming intensifies, the silent heat of night hours increasingly stresses wheat physiology, eroding yields even when daytime conditions appear manageable.

The pre‑print leverages four decades of field data from 255 locations, covering the breadth of spring‑wheat production zones. By isolating daily minimum temperature (Tmin) during the grain‑filling window, researchers uncovered a linear relationship: each 1 °C rise in Tmin reduces yield by about 0.5 t ha⁻¹. When combined with solar radiation metrics, Tmin explains more than half of the observed yield variability. The mechanisms are twofold—shortened grain‑filling periods and amplified dark respiration, which together siphon carbon that would otherwise fill the grain.

These findings have immediate implications for breeders, agronomists, and policymakers. Developing wheat varieties with enhanced tolerance to elevated night temperatures could reclaim the 10%+ yield losses projected under modest warming scenarios. Meanwhile, agronomic practices such as adjusted sowing dates, canopy management, and irrigation timing may mitigate nocturnal heat stress. As climate models forecast continued night‑time warming, integrating Tmin considerations into global food‑security strategies becomes essential to safeguard wheat’s role in feeding the planet.