Abstract

--- - Most plant thermal tolerance studies focus on single critical thresholds, which limit the capacity to generalise across studies and predict heat stress under natural conditions. In animals and microbes, thermal tolerance landscapes describe the more realistic, cumulative effects of temperature. We tested this in plants by measuring the decline in leaf photosynthetic efficiency (FV/FM) following a combination of temperatures and exposure times and then modelled these physiological indices alongside recorded environmental temperatures. We demonstrate that a general relationship between stressful temperatures and exposure durations can be effectively employed to quantify and compare heat tolerance within and across plant species and over time. Importantly, we show how FV/FM curves translate to plants under natural conditions, suggesting that environmental temperatures often impair photosynthetic function. Our findings provide more robust descriptors of heat tolerance in plants and suggest that heat tolerance in disparate groups of organisms can be studied with a single predictive framework. - Plant thermal tolerance studies often focus on single critical thresholds, limiting the capacity to generalise across studies and effectively predict heat stress, whereas, in animals and microbial studies, the thermal tolerance landscape framework represents the more realistic, cumulative effects of temperature. We applied this in plants, measuring the decline in leaf photosynthetic efficiency (Fv/Fm) across multiple temperatures and exposure durations, and then using a dynamic model, we show how Fv/Fm curves can be applied to predict heat stress in plants under natural conditions. Utilising this approach in plants opens the prospect for meaningful predictive comparisons of thermal limits, not only among plants, but also across biological kingdoms.image