桐麦间作地能量平衡和水分利用状况及其与产量的关系

RELATION BETWEEN ENERGY BALANCE, WATER USE STATUS AND WHEAT YIELD

农桐间作条件下的能量平衡及水分利用状况都发生了变化。与对照相比,间作第7年林下的净辐射及其各分量均有降低,而显热通量占净辐射的比重(H/R_n)减小,潜热通量(LE)和土壤热通量(G)与净辐射(R_n)之比均高于对照。同时农桐间作减少了水分相对亏缺。泡桐对这些因子的影响与其密度、生长期有关。由于间作地内能量平衡分配合理,利于小麦拔节、抽穗及开花期的生长,但在小麦成熟期、在大密度间作田里,由于净辐射损失严重,小麦生长及产量受到影响。在泡桐行距小于20m时小麦平均产量减少,大于20m时增加。

This study focused on the effects of different spacings of Paulownia elongata on energy balance and yield of intercropped wheat in paulownia-wheat intercropping field. Results showed that the net radiation (Rn) and its components were reduced in the intercropped wheat field compared to the control plots. However, the proportion of sensible heat flux(H) to Rn decreased while those of the latent heat flux(LE) and soil heat flux (G) increased. At the same time, water relative deficit in the intercropped plots decreased. Effects of paulownia trees on these parameters depended on its density, growth stage, the modified energy balance was favorable to wheat growth during jointing, heading and flowering stages in all paulownia spacings. However, the reduced Rn in denser paulownia spacings caused less favorable effect on wheat growth during grain filling and mature stages. the yield of intercropped wheat was found to vary with paulownia density and with the wheat plants' relative distance from the paulownia tree rows. Paulownia did not affect wheat yield in spacings larger than 5×20m but caused a decrease in spacings of less than 5×20m at the 7th intercropping year.