干旱对不同抗旱性冬小麦旗叶光合及主茎干物质转运的影响

Effects of drought on photosynthesis of flag leaf and dry matter remobilization of main stem in different varieties of winter wheat

以冬小麦品种长武134(抗旱性强)和陕253(抗旱性弱)为材料,研究干旱对旗叶净光合速率和叶绿素含量、主茎及其组成节间花前积累干物质的转运及其对穗粒重贡献的影响。结果表明,干旱条件下长武134主茎穗粒重降幅小于陕253;干旱缩短了小麦花后旗叶光合速率高值持续期(PAD)和叶绿素含量缓降期(RSP),长武134受影响程度较小。长武134除穗下节外,其余各节间及茎杆干物质转运量及对籽粒贡献率降幅均大于陕253;干旱提高了陕253穗下节和倒二节干物质转运率,降低了倒三节和下部节干物质转运率,茎杆干物质转运率无明显变化;长武134除穗下节外其余各节间及茎杆干物质转运率均明显低于对照,而且距离穗部越远的节位降低幅度越大。上述结果表明,干旱条件下不同节位干物质转运能力变化与距离穗远近有关,花前茎杆干物质转运并不能补偿籽粒产量的损失,花后旗叶光合功能期延长是小麦抗旱高产的主要原因。

Two kinds of winter wheat （Triticum aestivum. （ drought-sensitive）, flag leaves, and the were applied to study the effects of drough dry matter remobilization that accumulated L）, Changwu 134 （drought-resistant） and Shan 253 t on the net photosynthetic rate at the main stem, constituent and its contribution to gain weight per ear. The result showed Changwu 134 was significantly less than that of Shan 253 under and chlorophyll content of internodes at pre-anthesis that the extent of reduction of grain weight per ear in 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 intemodes 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 intemodes 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 intemodes was related to their distance to ear under drought condition; （b） the dry mat- ter 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.