春小麦籽粒灌浆期旗叶^（14）C－同化物在库端卸出的昼夜变化

DIURNAL CHANGES IN SINK UNLOADING OF (14)￣C- ASSIMILATES FROM FLAG LEAVES OF SPRING WHEAT DUKING GRAIN FILLING STAGE

本试验利用（１４）￣Ｃ示踪法研究了３个春小麦（ＴｒｉｔｉｃｕｍａｅｓｔｉｖｕｍＬ．）品种籽粒灌浆期旗叶同化物库端（穗）卸出的昼夜变化。研究表明，在籽粒灌浆期，旗叶（１４）￣Ｃ－同化物在库端（穗）卸出非常迅速，在标记后２４小时内，植株中５４％～７０％的（１４）Ｃ－同化物分布在穗部，尤其是穗中（１４）Ｃ－淀粉等贮藏性物质含量几乎呈直线上升。虽然如此，但是穗中（１４）￣Ｃ－可溶性同化物却出现积累或饱和状态，这说明库活性是有一定限度的，源（叶等）能为库提供充足的同化物。同一品种旗叶上午同化的（１４）Ｃ－同化物在穗中合成淀粉等的速率快于下午同化的。不论上午饲喂还是下午饲喂（１４）￣ＣＯ２，中８５０２、中８９０４穗部（１４）￣Ｃ－淀粉等含量在饲喂后２４小时内，总的来说均显著高于克７４－２０２，而其穗中（１４）￣Ｃ－可溶性同化物在标记１０小时后、２４小时内显著低子克７４－２０２，这说明它们穗中淀粉等合成速率快于克７４－２０２，故而表现出较强的库活性。收获指数与库活性相关。

The diurnal changes in sink unloading of (14)￣C-assimilates from flag leaves of spring wheat(Triticum aestivum L. )of three cultivars(Zhong 8502, Zhong 8904 and Ke74-202 )duringgrain filling stage were investigated by means of (14)￣C tracer technique. The study skowed that54%～70%of (14)￣C-assimilates of flag leaves was transported to ears after 24h.The amount ofnon-soluble (14)￣C-assimilates(mainly starch)in ears increased nearly linearly with time during24 hours.The increasing trend or soluble (14)￣C-assimilates in the ears indicated that the supplyof assimilates from source exceeded the demand of sink and the sink activity was limited . Theamount Of non-soliuble (14)￣C-assimilates in ears of the two cultlvars Zhong 8502 and Zhong8904, wbich had greater harvest index and grain welght, was significantly greater than thatof Ke74-202,but the amount of soluble (14)￣C-assimilates in ears was opposite,indicating thatthe formers had a greater sink activity.The rate of starch syntkesis with (14)￣C-asssilnilates wasgreater in the morning than that in the afternoon. The harvest index or grain weight may berelated to sink activlty.