Studies On Growth Rules And Cultivation Technique Of Loquat In Sunlight Greenhouse In The North China

Loquat is an adeciduas ardor, one of main fruit tree species in the south of our country. It is distributed in all provinces in the south of northern latitude 33. 5° , and can't be cultivated in the open of high latitude. This test takes advantage of microclimate environment in the north greenhouse to introduce fruit tree from the south. Through many years' introduction and trial planting, study and exploration on growth and development rhythm , raising seedlings and cultivation technique of loquat in sunlight greenhouse in the north China are carried on. The test results are as follows:Under cultural environment in sunlight greenhouse in the north, lengthening growth and leaf unfolding of loquat shoots have 4-5 peaks in all year, and thickening growth have 2-3 low peaks in the winter and spring, while 2 high peaks in the summer and autumn. The beginning time of every phenophase is:Spring shoot occurring begins in late January;summer shoot occurring begins in early to middle June;autumn shoot occurring begins in middle August;winter shoot occurring begins in middle to late November;flowering period begins in middle to late October;and bearing period begins in early to middle March. If there are warming facilities in the greenhouse, and the lowest temperature is kept over 10℃ in winter, the beginning time of bearing period is in middle to late February.Young plants of 'Dahongpao' and 'Guanyu' loquat cultivars sprount many shoots .especially summer shoots is the most. Floral rate of shoots is high. Floral rate of shoots and plants of two-year-old 'Dahongpao' loquat are 28. 6% and 83%, floral rate of plants of four-year-old 'Dahongpao' loquat is 100%. The 'Dahongpao' loquat which bears fruit early and has a high yield is suitable for cultivation in sunlight greenhouse in the north China.Loquats in the greenhouse bloom in October to November and bear fruit in December. Three development periods of 'Dahongpao' loquat fruit in sunlight greenhouse is development period of young fruit (from late November to late January) , development period of seed (from late January to early February) , and the period of quick expansion of flesh and fruit ripening (from middle February to early to middle Match) . Development and ripening of fruits onlyneed 3~4 months. Ripening date may be in February to Match before the due date. Loquats have great potential in the winter fruit market. But there is a relatively slow growing point in the development period of young fruit and the period of quick expansion of flesh and fruit ripening. It may be related to environment or it may be the growing feature of loquats before riping. This needs studying further.During the development of 'Dahongpao' fruit in sunlight greenhouse, longitudinal diameter is larger than horizontal diameter, the growing speed of longitudinal diameter is quicker than that of horizontal diameter , average weight of a fruit (25. 08g) is lighter than that of producing area (37.OOg), shape index of fruit is 1.49, and there is only one seed in a fruit. This is different from producing area (shape index of fruit is 0.88, there are one tofive seeds, most of them have three seeds) .Less than three-year-old trees may not be cut, except some too long shoots. With the growth of trees, Open center type of the tree should be used in the south of greenhouse. Stratified crown on the main shaft of the tree be used in the north of greenhouse, stratal numbers should be decided by height of the greenhouse. Thinning-out and decurt pruning can be used to adjust amount of branches. For the declining cultivar, some branches should be lifted up, while for the straight cultivar, widen crotches and whorl decortication can be used.The proper plastic-covering time of loquat cultivated in greenhouse is before early frost, that is in early to middle September. The proper straw curtain-covering time is in middle to lateral October, that is, before the night tempreture drops to 0°C. The proper time of cover—removing and cultivating outdoors is in May.Propogation method of loquat is grafting by co-rootstock. stock seeds should be sown early after collecting them and covered soil should be thin to ensure orderly seedlings. Grafting methods may be cleft, bast cutting and cutting graftage. After grafting, some leaves of stock should be saved to ensure supply of water and nutrition for stion. Shoots of stock can t be cut too early, otherwise, it would affect water transportation of stock, decrease survival percentage of stem grafting, meanwhile make stock die down.