大豆和蚕豆苗期根系生长特征的比较

Root growth characteristics of soybean and faba bean at their seedling stage

大豆和蚕豆是西北地区间套作生产中广泛种植的豆科作物,但二者在与禾本科作物间作时差异十分明显,蚕豆相对于大豆具有更强的竞争能力.从大豆和蚕豆的根系入手,研究了大豆和蚕豆在苗期根系生长发育和形态的差异.采用PVC管砂培装置,通过扫描仪扫描根系,用图像分析软件WinRHIZO进行了研究.结果表明,出苗42 d时,蚕豆根表面积是大豆根表面积的2.61倍;出苗14 d时,大豆根系在整个砂层中均有分布,而蚕豆根系只分布在表层;大豆根较细,大部分根的直径为0.25～1.0 mm,相对于大豆而言,蚕豆根较粗,大部分根直径为0.5～1.5 mm.蚕豆根较粗,所以有更大的表面积,而且它的根系分布在上层的比例大于大豆,这些因素决定了它的吸收能力强于大豆,能更好地利用上层土壤养分.这是蚕豆竞争能力强于大豆的原因之一.

Soybean and faba bean are the two main legumes widely intercropped with cereals （e. g., wheat or maize） in western China, but have significantly different performance in intercropping system. Compared to soybean, faba bean has a stronger competitive ability. Considering that underground interspecific interaction makes a significant contribution to the advantage of intercropping system, a pot experiment was conducted to compare the differences in root growth and morphological parameters between soybean and faba bean at their seedling stage. A PVC tube, with 10 cm in diameter and 50 cm in depth, was filled with quartz and used to grow the crops. Root systems were scanned by a scanner, and analyzed by WinRHIZO on days 14, 21,28, 35 and 42 after seedling emergence. The results indicated that on the 42nd day after seedling emergence, the root surface area of faba bean was 2.61 times larger than that of soybean. Soybean roots distributed in the whole layer of quartz on the 14th day, but most faba bean roots only distributed in its top layer. Soybean roots were thinner, and most of them were 0.25 ～ 1.0 mm in diameter, while faba bean roots were thicker, and their diameter was mostly between 0.5～1.5 mm. All of these facts resulted in a higher absorption capacity and nutrient use efficiency of faba bean, which could be one of the reasons that faba bean had a stronger competitive capacity than soybean.