重茬对大豆冠层结构和产量的影响

EFFECT OF CONTINUOUS CROPPING ON CANOPY STRUCTURE AND YIELD OF SOYBEAN

为了深入探讨重茬导致大豆减产的因素及解决重茬带来的生产障碍对策,采用"大田切片法"研究了大豆不同茬口类型(正茬、一年重茬和两年重茬)的冠层结构和产量变化。结果表明:重茬大豆冠层不同层次叶面积均低于正茬大豆,并且分枝数、荚数和荚重有相同的变化趋势,变化幅度随重茬年限增加而加剧。正茬大豆冠层叶片上、中、下层结构分布合理,重茬一年冠层叶片分布上层较多而中、下层较少,重茬两年叶面积在不同层次均有降低。重茬一年和两年分别较正茬大豆减产13.6%和38.6%。群体质量显著降低是重茬大豆减产的主要原因。

Continuous cropping is one of major factors limiting soybean [Glycine max （L.）Merri. ] yield. In order to discuss yield limiting factors of continuous soybean, three cropping types, including normal rotation （NR）, one-year continuous cropping （OCC） and two-year continuous cropping（TCC） were adopted and the canopy structure and yield of three cropping type soybean were studied with the conventional ＂Layer upon layer cut method ＂. Leaf area of continuous cropping soybean at different canopy layer was lower than that of normal rotation soybean and so was the branch number, pod number and pod weight, and the scope intensified with the increasing of the continuous years. Leaves distributed more rational among the upper, middle and lower layers of the canopy under NR. There were more leaves in the upper layer of canopy under OCC. The leaf area at different canopy layers of TCC decreased significantly compared to NR. The yield of OCC and TCC soybean decreased 13. 6%and 38.6% compared to NR, respectively. The results suggest that the decreasing of the population quality is the key reason to the yield reducing of continuous cropping soybean.