Effects of drought on photosynthesis of flag leaf and dry matter re mobilization of main ste min different varieties of winter wheat
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DOI:10.7606/j.issn.1000-7601.2009.05.31
Key Words: wheat  drought resistance  dry matter  remobilization  stem  internodes
Author NameAffiliation
WANG Zhenghong State Key Laboratory of Soil Erosion and Dryland Far ming on Loess Plateau Northwest A &F University, Yangling, Shanxi 712100, ChinaAgricultural College Henan University of Science and Technology, Luoyang, Henan 471003, China 
DENG Xiping State Key Laboratory of Soil Erosion and Dryland Far ming on Loess Plateau Northwest A &F University, Yangling, Shanxi 712100, China 
LIU LiSheng State Key Laboratory of Soil Erosion and Dryland Far ming on Loess Plateau Northwest A &F University, Yangling, Shanxi 712100, China 
ZHAO Ziping State Key Laboratory of Soil Erosion and Dryland Far ming on Loess Plateau Northwest A &F University, Yangling, Shanxi 712100, China 
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Abstract:
      Two kinds of winter wheat (Triticum aestivum.L) , Changwu 134 (drought-resistant) and Shan 253 (drought-sensitive) , were applied to study the effects of drought on the net photosynthetic rate and chlorophyll content of flag leaves, and the dry matter remobilization that accumulated at the main stem, constituent internodes at pre-anthesis and its contribution to gain weight per ear.The result showed that the extent of reduction of grain weight per ear in Changwu 134 was significantly less than that of Shan 253 under drought conditions.Both photosynthetic active duration (PAD) and relative steady phase of chlorophyll content (RSP) of flag leaves in two winter wheat varieties were shortened by drought.In contrast with Shan 253, however, drought impact that imposed to changwu 134 was relatively small.Besides peduncle, the decreased degree of dry matter remobilization and contribution rate to grain yield of stem and its constituent internodes of Changwu 134 were significantly lower than those of Shan 253.Under drought condition, the dry matter remobilization rate of peduncle and penultimate of Shan 253 increased significantly the and third internode’s and lower internode’s decreased significantly, but the stem’s had no obvious changes.The dry matter remobilization rate of stem and its other internodes of Changwu 134 were significantly lower than that of control besides peduncle, and the longer distance to the ear, the higher decreased degree.In conclusion, above results could suggest: (a) the dry matter remobilization ability of different internodes was related to their distance to ear under drought condition; (b) the dry matter remobilization that accumulated at pre-anthesis at the main stem was not enough to compensate for yield loss; (c) the extension of active photosynthesis duration was the main reason for wheat’s drought resistance and high yield.