Experiment on Breeding of Pinus sylvestris L. var. mongolica Litv. in Arid Desert Area

Pinus sylvestris\% L. var. \%mongolica\% Litv. originates in the sandy lands of northern Greater Hinggan Mountains and Hulunbuir steppe. It is one of the fast growing commercial forests and supprious wind preventing and sand binding species because of its characters of drought resisting, cold tolerating, poor soil bearing, fast growing and long standing. \;It has been introduced to sandy lands of Northern Shaanxi, Ningxia, Ganshu, Qinghai and Xinjing since 1950s. In arid desert areas, the principal influencing factors on breeding of \%P. sylvestris\% are low temperature, low humidity and frequantly blowing gale in spring; hight temperature and aridity, low soil water holding capacity in summer. The key measures for breeding successfully consist of improving soil, mulching breeding bed in spring, irrigation, shadowing, covering for surviving winter, and fertilizing and applying pestcide.