[Root growth characteristics of soybean and Faba bean at their seedling stage]

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 approximately 1.0 mm in diameter, while faba bean roots were thicker, and their diameter was mostly between 0.5 approximately 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.