Diverse responses of multiple crops to drought and salinity stress

Food security is threatened by co-occurring stresses (e.g. salinity and drought) under global climate change. To circumvent major impacts on food production, the vulnerabilities and tolerances to these threats need to be characterized. Traditionally, the tolerance of crops is evaluated in highly controlled small-scale experiments involving only a limited number of crop types. To increase our understanding in actual agricultural tolerances, plant functioning, as observed by functional traits, need to be performed in real-life scenarios for as many crops as possible. Remote sensing is presently the only tool capable of monitoring such plant functional traits simultaneously over large areas.

The aim of this research therefore is to evaluate the crop tolerances to combined drought and salinity stress across various plant functions in real-life conditions. We evaluated drought and salinity tolerance impacts on different types of crops across the entire US continent, using five traits representative of different plant functions. Given crop tolerance highly depended on the moments, we evaluated the dominant stress and the onset among individual and combined effects of drought and salinity for five traits from March to October.

We found strong interaction effects between stress and time using two-way ANOVAs. In general, crops were more sensitive to combined drought and salinity, although they differ significantly between species and moments. Of the individual traits, LAI was triggered first by stresses, followed by FAPAR and FVC, and Cab and Cw were the last to respond to stresses. This implies that plants reduce primary production before reducing water content.

Our study provides a way of evaluating the tolerance of diverse crops to co-occurrence stresses both separately and in combination. Through applications to other vegetation types and stresses, our approach creates a quantitative backbone to inform sustainable food production.