桐麦间作系统小麦光合生理适应性规律的研究

桐麦间作系统内外的对比研究表明，试验期间系统内小麦平均光能利用率是系统外的１３３．３％，光能利用率在１１时～１３时之间最低．整个时段平均光合速率为系统外对照点的８７．６％，其中，小麦抽穗开花期为９７．９％，灌浆期为８６．３％，成熟期为７８．６％．桐麦间作对小麦光合作用的影响主要在灌浆期与成熟期．光合速率在１１时～１３时之间是最大的，呈单峰曲线．桐麦间作系统对小麦叶面Ｂａｌ Ｂｅｒｙ指数的影响，表现在灌浆期末期和成熟期，在小麦抽穗开花期没有影响．从抽穗开花期到灌浆期和成熟期，小麦光合作用与光量的关系逐渐减小．

Changes of Wheat Photosynthetic Characteristics in the Inter Cropping System of Paulownia Wheat

The comparison study between the wheat crops outside the inter cropping system of Paulownia wheat with that inside the system reveals that, the mean photosynthetical light use efficiency of the wheat crops inside the system was 133.3% of that outside the system, therefore inter cropping system of Paulownia wheat is an effective way to increase the photosynthetical light use efficiency (PUE) of the whole system.PUE was the lowest between 11:00 and 13:00 during a day in the experiment. The mean photosynthetic rate of the wheat crops inside the system was 87.6% of that outside the system; or 97.9%, 86.3% and 78.6% of that outside the system during the stages of flowering, grain filling and maturing, respectively. The influence of trees on wheat crops inside the system was only significant from grain filling to maturity stages.Photosynthetic rate of wheat leaves was maximal between 11 and 13 o'clock and the diurnal variation of leaf photosynthesis was sinusoidal. The influence of trees on the Ball Berry index of the wheat leaves inside the system was insignificant during flowering, but significant during grain filling to maturing, similar to the influences of trees on the leaf photosynthesis of wheat crops. The dependence of leaf photosynthesis of the wheat crops on the absorbed light was weakened from flowering to maturing. This physiological characteristics of wheat crops are the key to the success of inter cropping system of Paulownia wheat.