The Response Mechanism and Threshold of Spring Wheat to Rapid Drought

In order to deeply understand the effect mechanism of rapid drought stress on physiological and biochemical properties crop leaves determine thresholds, potted spring wheat under two water treatments, adequate supply continuous stress, was researched. early stage drought, parameters decreased in stomatal conductance (gs), intercellular CO2 concentration (Ci), maximum electron transfer rate (Jmax), mesophyll (gm), photosynthetic (Pn,) leaf content (LWC), triose phosphate utilization (TPU), transpiration (Tr), carboxylation (Vcmax). Photosynthesis dominated by limitation also limited limitation. The mainly caused reduction transport capacity. late first decreased, then decreased. During extreme With decrease relative soil moisture (RSM), except for Ci, which increased, other physicochemical all showed an S-shaped, decreasing trend. Mild severe thresholds were determined be 56.6% 43.6% RSM, respectively, according curve’s inflection point, corresponding 16.6% about 52.2% average initial amplitude among parameters. This will provide a reference monitoring as well warning wheat.