间作时期和种植密度对甜瓜/向日葵间作系统光能利用效率的影响

以单作为对照,通过大田试验研究了间作时期及种植密度对甜瓜/向日葵间作系统土地利用率及光能利用率的影响。结果表明:各间作处理的土地当量比(LER)都大于1,说明甜瓜/向日葵间作显著提高土地利用率。除甜瓜定果期间作外,其他间作处理的光能利用率都显著大于甜瓜单作;除甜瓜45 cm株距间作外,其余间作处理的光能利用率均显著小于单作向日葵。甜瓜/向日葵间作能明显提高间作系统的叶面积指数,种植密度对叶面积指数也有影响。调整间作期能延长单位面积的光合时间,增加干物质累积,提高光能利用率。叶日积与光能利用率之间呈二次抛物线关系,当作物群体密度增大时,叶日积和光合产物累积量都增大,但密度增长到峰值时,叶日积继续增大不能增加光合产物积累量。

Effects of Intercropping Time and Planting Density on Solar Energy Utilization Efficiency of Melon/Sunflower Intercropping System

A field experiment was conducted to investigate the effects of intercropping time and planting density on land and energy utilization of melon/sunflower intercropping system. The results showed that the land equivalent ratios (LER) of the intercropping treatments were greater than one, indicating significantly increased land utilization rate of melon/sunflower intercropping system. The solar energy utilization efficiencies of other intercropping treatment were significantly higher than that of the monocultured melon except in the fruit expanding period, but were significantly less than that of the monocultured sunflower except for the 45cm spaced intercropping treatment which showed similar solar energy utilization efficiency with monocultured sunflower. Melon/sunflower intercropping significantly increased the leaf area index which was also affected by planting density. The adjustment of intercropping time could prolong the photosynthetic period resulting in an increased dry matter accumulation and solar energy utilization efficiency. A quadratic parabolic relationship was found between leaf area day (LAD) and solar energy utilization efficiency. As the crop population density increased, LAD and assimilates accumulation also increased until it reached a peak, afterward the increased LAD could not result in further accumulation of assimilates.