小麦不同品种光合速率和14 C同化物分配对源库比改变的影响

 选用千粒重大小不同的小麦品种，研究了去除顶端两个小穗对两类品种(大粒品种和小粒品种)穗部性状、籽粒平均灌浆速率、单穗平均增重速率、植株光合速率及14C同化物运输分配的影响。试验结果表明，去除顶端两个小穗后，两类品种的籽粒平均灌浆速率和单穗平均增重速率(分别表征籽粒库容活性和穗粒库容活性)相应提高，穗粒重表现为补偿性增长。两类品种比较，小粒品种的增长幅度大于大粒品种。穗粒库容活性增强使得小粒品种灌浆中后期的植株光合速率提高，使两类品种分配到籽粒中的14C同化物比例增加。从而表明，无论是植株光合速率还是同化物的运转分配皆受库容活性的调控，调控方式和幅度因品种类型而不同。

Photosynthetic Rate and Distribution of 14C Assimilate in Different Wheat Cultivars in Response to Altered Source Sink Ratio

Wheat cultivars of different grain weight (representing small or large grain cultivars re-spectively) were selected as experimental materials, the effect of removal of top two spikelets on average grain filling rate, average increment rate of ear weight, photosynthetic rate and partitioning of 14C assimilate during grain filling in winter wheat plant were investigated. When the top two spikelets were removed at anthesis, the average grain filling rate and average increment rate of grain weight per ear increased accordingly, resulting in compensatory increase of grain weight per ear. Compared with large grain cultivars, the increase magnitude of small grain cultivars were much higher. Resulting from strenthened sink activity, the photosynthetic rate of small grain cultivars at middle and final stage of grain filling and the partitioning of 14C assimilate into the grain of all cultivars were increased. Conclusively, both the photosynthetic rate and the partitioning of 14C assimilate were controlled by sink activity, but the regulation mode and magnitude were dependent on the types of cultivar.