A comparison of adaptive cultivation of eighteen alfalfa varieties in the Qinghai Plateau

Eighteen alfalfa varieties were compared on their performances in Qinghai Plateau in 2009－2010. In the first planting year (2009), the root length, root diameter, number of branches per plant and plant height were 22.6-31.9 cm, 4.1-8.8 mm, 4.1-6.8, and 43.9-80.1 cm, respectively. No significant difference was observed among varieties during the early flowering period in 2009.The highyield period appeared in the second planting year (2010); and the number of branches per plant increased by 1.5-10.5 times. The height of plants at the first mowing in 2010 was 110.7-145.4 cm, which was one time higher than that in 2009. Varieties of Sandeli, Debao, WL232 gave the highest fresh forage and hay yield in 2010, which were between 106 614-121 364 kg/ha and 30 761-34 934 kg/ha, respectively. America Zajiao, Defy32IQ, Sitel, Nongbao, Algonquin ranked 4th-8th with 91 922-102 822 kg/ha of fresh forage and 25 410-29 036 kg/ha of hay forage. These eight varieties had better performances than other varieties, which indicated they were suitable for cultivating in eastern agricultural areas of the Qinghai Plateau.