Study on ecological adaptability of alfalfa introduced from foreign countries in BeUing area

The results from three year’S continuous experimental study on the alfalfas of introductory varieties show that the alfalfa varieties with fall-dormancy grades 2～5 are suitable to be cultivated in north of North-China Plain，meanwhile some counterm easures must he taken to enhance the survival rate in winter；the varieties with falbdormancy grades 6 and 7 can not be spread out；the three varieties Haygarzer，Vector and Key can be harvested from 4 to 5 crops annually，and are suitable to be cultivated in Bering area；the alfalfas survive safely in summer in Beijing area，but some prevention measures must be taken to resist plant diseases and insect pest；the relation between the output and accumulative temperature of alfalfa is linear in that sowing year，and logarithmic in the following years．