Dry-hot wind effects on physiology of winter wheat

Weather conditions of dry-hot wind were simulated by artificial control to compare the effects of heavy and light degree of dry-hot wind on winter wheat physiology in field at early and middle grain filling stages. The results showed that the dry-hot wind at middle stage of grain filling had more negative effects than at early stage of grain filling,and the heavy-grade dry-hot wind harmed more than the light-grade one. On the 2nd day after heavy dry-hot wind occurred at middle stage of grain filling,the photosynthetic rate( Pn),transpiration rate( Tr) and stomatal conductance( Co) of flag leaf decreased by 19.4% to 36.6%,44.1% to 58.0%,and 24.3% to41.7%,respectively. For light dry-hot wind,the above index decreased by 9. 7% to 20. 2%,28.2% to 34.0%,and 19. 9% to 31. 8%,respectively. The decreased percentage of SPAD and root flux activity( Gn) also reached the maximum with the heavy-grade dry-hot wind at middle stage of grain filling. There was no obvious stressed effect on winter wheat for light-grade dry-hot wind at early stage of grain filling. At early stage of grain filling,Pnand SPAD of flag leaf could repair to a certain extent after dry-hot wind weather,but the damaged physiological indexes could not be repaired when the dry-hot wind occurred at other stages. Under the condition of Co 0. 1mmol·m-2·s-1,the stressed effects on Trwere more than on Pn.