ADAPTABILITY AND USE OF INTRODUCED CULTIVARS OF PYRUS PYRIFOLIA NAKAI IN GANSU PROVINCE OF CHINA

The paper illustrates the geographical, the geomorphologic and the climatic features and Pyrus plant resources of Gansu province of China. It is based on the investigation and study of the growth, fruit habit, phenophase, fruit economic character and the resistances to freezing injury, late frost, drought, salt damage, etc. of 50 cultivars of Pyrus pyrifolia Nakai including 28 pear cultivars of Japan. The paper summarizes and analyses the adaptability of the cultivars of Pyrus pyrifolia Nakai to different ecologic conditions of Gansu province over the last 50 years:

1. The adaptability becomes weaker and weaker from the east part to the west part. The ideal places to plant the cultivars are southern region, the southeast part and the Huanghe valley of the middle part of Gansu province. The selected cultivars of Pyrus pyrifolia Nakai are Nijisseiki (Japan), Kikusui (Japan), Ninomiyahakuri (Japan), Housui (Japan), Shinsui (Japan), Shinseiki (Japan), Atago (Japan), Huangmi (China), Cangxixueli (China), Huangguan (China), Ganli8 (China), Huasu (China), etc. All of these cultivars possess the characteristics of early fruit-bearing, good quality, fruitfulness and high yield in early time, etc.
2. Because of the low temperature, aridity and late frost in the middle part, Hexi corridor and southwest part of Gansu province, the branches are easily damaged during winter and the flower organs are easy to be damaged by late frost. All of these causes affect the development of pear cultivars of Pyrus pyrifolia Nakai in these places.
3. Because of the adequate sun-light, big difference in the temperature between day and night, low humidity, etc. in Gansu province, the fruits of the cultivars of Pyrus pyrifolia Nakai in Gansu province are more colorful, smoother and better quality than the fruits in other provinces of China.
4. Because of the characteristics of early fruit-bearing and good quality, the cultivars of Pyrus pyrifolia Nakai especially pear cultivars of Japan are thought to be the ideal parents to breed good cultivars of pear, to which close attention will be paid in the 21st century.