The Effect Of Physical Character Of Substrate On Cucumber Seedling Quality And Growth

In this article, in favor of the conditions of lacking research in the standard of plug seedling raising, 7 compound growing substrates which are different in physical properties are studied for their influence to cucumber seedlings quality in different seasons and cucumber development and growth. The results are as follows:The porosity of the growing substrates is the main factor governing the cucumber seedlings quality. The ventilation property can influence the germination rate. Larger pores, which provide more space for ventilation, will make seedlings grow faster and consistently. Water containing in pores can influence the scale of cotyledons and leaves, while larger pores will also make cotyledons and leaves larger. When total porosity reaches approximately 70% and the ratio of water to air reaches 3-4, the growing substrates will greatly promote the seedlings growth. It will further influence the root activity, chlorophyll content, photosynthesis rate and other physiological indexes. The regressing model of relation between vigorous seedlings and 3 growing substrate indexes: bulk density, ventilating pores and water containing pores are constructed. The regressing model reaches the dominant level. When the seedlings raising are carried out in February, total porosity reaches approximately 70% and the ratio of water to air reaches 3-4, the main problem is water containing pores.In order to study the influence of physical properties of growing substrate to seedling quality under different temperature and light conditions, cucumber seedlings are raised in February, May, September and December respectively. Indexes of light, temperature, germination rate, scale of cotyledons and leaves, vigorous rate, root activity and chlorophyll content are measured. It indicates that the effect of light and temperature contributes more to the seedling quality than physical properties of growing substrate. It will dominantly influence the germination date and scale of leaves. It also shows that the ratio of water to air in 3-4 is fits to all seasons. When just considering the water and air, however, the ratio can be elevated to 5 in the high temperature season.In order to study the influence of the seedling quality to cucumber growth and development, seedlings in all growing substrates are transplanted in greenhouse. It shows that the seedling quality will dominantly influence the plant height, leaf number, the largest scale of leaf and the blossoming date. In all 7 growing substrates, No.1, No.2, No3 and No.4 which contains more vigorous seedlings maintain their predominance in cucumber growth and development: plant height and the largest scale of leaf are dominantly higher than other treatments, the blossoming dates are also bring forward. The earliest one is treatment No.l. The blossoming date of it is 2-6 days earlier than others. Also, the better quality of seedling can greatly enhance the prophase and total yields. The correlation between vigorous seedling rate, growth function and prophase and total yields are significant. These 2 indexes can forecast the yield, so that they can be significant standards to evaluate the cucumber seedling quality.