Effect Of Covered With Coloured Plastic Film On The Soil Conditiong Of Root And The Growth Of Onion

Onion (Allium cepa L.) is the world's No. 3 major vegetable crops, and cultivated throughout the world. Onion in most of North China for the autumn-transplanting and summer-harvesing, so mulching will provide adaptive wintering in open field and it performanced better yield. In recent years, with the development of the plastics industry, plastic film developed the more type and functionality. Compared with currently used transparentfilm, colored film also have functions of regulate the environment, suppresing weeds, controling crop growth and resistance to pests and diseases. However, the production of onions using transparent plastic film ordinary, colored plastic film mulching on the growth and development of onion has not been reported. In this paper, using 'Earth' as the test material, and studying the colored plastic film mulching on soil environment and onion growth and development, production quality and physiological characteristics. The main test results are as follows.1. The effect of colored plastic film mulching on rhizosphere soil of onion is significant differences. Transparent plastic film mulching has good ability in increasing soil temperature than other film, and provide suitable soil environment in the winter and plant vigorous growth stage. The temperatures of transparent film is higher than black and silver plastic film in lant vigorous growth stage. But the temperature of transparent plastic film is too high to saving water in the last stage and caused premature of root and plant finally. So transparent plastic water-retention capacity was only better than CK. Because of the weak ability of increase temperature, root of onion covered black film was serious frostbited, and root growth was also affected. Silver plastic film gived the roots winter protection, and also provided a cool moist soil environment, promoted enzyme activity and improved the water and fertilizer situation in the bulb expanding stage. It promoted root growth and increased root activity in the last stage.2. Covering with colored plastic film can significantly improve the growth of onion. There is no significant difference in plant height, stem diameter and fresh weight of organs among the treatments except that of the control was lower during overwintering. The onion plant covered with transparent plastic returned growing earlier and grew more than silver and black plastic mulch in the next spring. But the high soil temperature induced by transparent film restrained the growth in May, so the onion covered with silver plastic film grew better than the treatment of transparent plastic film, but the onion with black plastic film treatment was poor, and the three treatments grew better than the control.3. The effect of the physiological characteristics of the onion which covered with colored plastic film was significant, but the effect is not similar covered diffect film in different periods. Transparent plastic film can significantly improve the leaf chlorophyll content, pn and enzyme activity in prophase. But root of covered transparent film is premature consenescence and it caused plant consenescence in the last stage of growth. Because of silver film provide suitable soil environment, the growth of overground part was promoted. And its enzyme activity and Pn was higher than other treatmnts.4. Two-year experiment results showed that covered with plastic film can significantly increase the onion yield and improve the quality of onion. The yield of onion mulched with silver, transparent and black plastic was 84404.2, 77403.9, and 70603.5kg·hm-2, and higher than the control by 158.90%, 137.42% and 116.56% respectively. Onion covered with transparent plastic film has the highest dry matter content, however, onion covered with silver plastic film has the highest Vc, soluble sugar, and soluble protein content.