Study On Variability Of Vegetable Quality In Different Pianting Condition Of Loess Plateau Abstract

Along with the planting structure's strategic adjusting in China, the production and utilization of vegetable crops have undergone many great changes. The concrete manifestation is that simplely pursuing quantity has transformed into concerning the vegetable nutrition, the taste, the luster, the fragrance as well as the edible safety for human health. This paper mainly studied the variety of vitamin C, soluble sugar, pH and nitrate content in different vegetables (cabbage, green leaf vegetable, legumes, etal) under different cultivating seasons (Spring, Summer, Autumn and Winter ), different cultivating models (open field, arched shed, solar greenhouse), and different climatic conditions (arid and humid-arid continental climate, warm temperate zone half moist monsoon continental climate) in Yang ling and Yan an areas.. Through analyzing the variability of nutrition vegetable quality(security and safety) in the different areas of Loess plateau (Yang ling and Yan an), different seasons, and different cultivating models, the result indicated as follows:1. The vegetable quality of spring was better in Yan an under the open field condition, vitamin C and soluble sugar content were higher. The nitrate content was higher in Yang ling. In these two areas, lower than the nitrate pollution, vegetables nitrate content belonged to the mild pollution, and only a few vegetables were polluted.2. Through analyzing the vegetable quality of spring under sunlight greenhouse, the arched shed and the open air planting conditions in Yan an, the soluble sugar content were as follows, open air planting > the arch shed planting > sunlight greenhouse planting, but for the vitamin C, the open air planting>sunlight greenhouse planting> the arch shedplanting. The vegetable quality under open air planting was better than facility planting. Different planting conditions has different influence to the vegetable security quality, the nitrate content were as follows, the arch shed planting> sunlight greenhouse planting> open air planting. These were mainly because of the massive usage of chemical fertilizer especially the nitrogen fertilizer, which caused the soil nutrient and salinity accumulated, nitrogen use efficiency reduced, the accumulation of soil nitrate severe, and the vegetable quality decreased.3. As the change of planting seasons, the qulity of open air planting cabbage and green leaf vegetable were as follows, both the contents of soluble sugar, vitamin C and the value of pH firstly increased, then decreased. However, the nitrate content firstly decreased, then increased in the open air planting conditions both in Yang ling and Yan an. Most of the soluble sugar, vitamin C content, pH and nitrate content of legumes, eggplant, roots vegetable, cabbage and onion were higher in the autumn than in the summer.4. Under sunlight greenhouse planting conditions and arched shed planting conditions, the soluble sugar and vitamin C content were higher in summer and autumn than in the winter and spring, but the nitrate content was higher in winter in these two areas.