Onset and severity thresholds of drought impacts on wheat

Drought often causes tremendous agricultural impacts and economic losses, but drought impacts are difficult to assess and quantify. Improving drought monitoring and early warning systems by linking indicators to impacts can reduce social vulnerability. However, it is still challenging to establish quantitative links between drought indicators and impacts during drought stress. In this study, using experimental observation records during drought in different climatic zones in China, we established the quantitative links between the drought indicator based on soil moisture and the affected biological parameters of wheat (Triticum aestivum L.), determined the thresholds of the onset and severity of the impact of drought on wheat, and found that the onset thresholds had a convergence across climate zones and the severity thresholds were different in different climate zones. This study may provide a new understanding for evaluating drought stress or severity and provide an important reference to better understand the hazard itself and carry out impact-based drought monitoring and early warning.