Physiological response cascade of spring wheat to soil warming and drought

Abstract

Climate change is affecting wheat production in Northern Europe; in particular, drought and soil warming during anthesis may cause significant yield losses of the crop. In a search for genotypes tolerant to these stresses, the physiological responses of three spring wheat cultivars to increased soil temperature (3°C above normal) (H), drought (D) and their combination (HD) were investigated. The plants were grown in pots in a climate-controlled greenhouse. Stomatal conductance (gs), photosynthesis (A), leaf water potential (Ψl), and relative water content (RWC) were measured during the treatment period. The responses of these variables to soil drying (for both D and HD) were described by a linear–plateau model, indicating the soil water thresholds at which the variables started to decrease in relation to the control plants. The H treatment alone hardly affected the variables, whereas both D and HD had significant effects. The variable most sensitive to soil drying was gs, followed by A, Ψl, and RWC. Among the three cultivars, earlier stomatal closure during drought in Alora could be a good adaptive strategy to conserve soil water for a prolonged drought, but may not be of benefit under intermittent drought conditions. Later stomatal closure and decline in A for Scirocco under HD and D stresses would be a favourable trait to sustain productivity under intermittent drought. A lower soil-water threshold of gs associated with a later decrease in A for Scirocco implies that the cultivar was less susceptible to HD and D stresses at anthesis.