[Root system development ability of several alfalfa cultivars in the hilly and valley regions of Loess Plateau].

A field study was conducted in the hilly and valley regions of Loess Plateau in Gansu Province to analyze the root system development ability of several alfalfa (Medicago sativa) cultivars. Eight introduced cultivars and one local cultivar were arranged in the same site. The secondary roots of alfalfa cultivars grew mainly from the taproot underground 10-20 cm depth, and there were no secondary roots below 50 cm depth. The total amount of secondary roots of Sandili and Ameristand 201 was the biggest, and that of Longdong alfalfa was the lowest. The volume and biomass of different cultivars were decreased from 0-10 cm depth to below 50 cm depth, except those of Sandili and Ameristand 201 at 20-30 cm depth was bigger than at 10-20 cm depth. The biomass of Ameristand 201 was 170.54 g and bigger than that of others, and that of Longdong alfalfa, which was 22.4% of Ameristand 201, was the lowest. According to cluster analysis on 9 alfalfa cultivars, Sandili, Ameristand 201 and Amerigraze 401 were suitable for planting on the hills and valleys of Loess Plateau due to their root system development ability.