Canopy temperature and heat stress are increased by compound high air temperature and water stress and reduced by irrigation — a modeling analysis

The mechanistic model couples canopy energy balance with soil–plant water transport and was parameterised for wheat. Under well-watered conditions, canopy temperature broadly followed air temperature; once soil water potential became more negative than about −0.14 MPa in the model, further drying caused canopy temperature to rise rapidly. At about −0.62 MPa, modelled canopy temperature could be up to roughly 10 °C above air temperature. Irrigation reduced canopy temperature by sustaining transpiration, but at high air temperatures it often could not keep the canopy below a heat-damage threshold, and its cooling benefit diminished as the background air temperature increased. These thresholds are model outputs for the parameterised system, not irrigation set-points for vegetables.

Conceptual transferability: this paper is valuable for mechanism and system design, but the crop, model or experimental configuration differs materially from Kumer production. Use it to decide what to monitor and test, not to copy its numerical outputs.

For Kumer 1687, the defensible use of this evidence is as a hypothesis and measurement framework to test against its own fields, lots and cold-chain records. A published result becomes a production rule only after local validation.