Studies On Applying Root Restriction Culture In Solar Greenhouse Cucumber

Effect of rooting-zone volume and rooting-zone nutrition on growth, physiological characteristics and yield of organic culture cucumber was studied in solar greenhouse .The main results were as follows:1. Plant height, stem diameter, leaf area, leaf number, root and shoot weight decreased with the decrease of rooting-zone volume. Root restriction raised the plant root/top ratio. Cucumber reaction schedule of root restriction was related to culture period and root restriction degree. In spring stubble, root restriction response of 4L, 8L, 12L treatments cucumber were respectively appeared after 49,64,79 days of setting; and were ahead of schedule 15 days respectively in fall stubble.2. Chlorophyll a, chlorophyll (a+b) and carotene content of cucumber leaves decreased due to rooting-zone volume restriction, but chlorophyll b content had a little influence. Transpiration rate, photosynthetic rate, stomatal conductance of 4L treatment cucumber leaves began to lower than those of the other treatments in middle-fruiting stage, but 8L and 12L treatments showed the difference in last fruiting stage. The root activity of root restriction treatments cucumber reached the peak at initial fruiting stage, and reducing with the times prolonging, more severe of root restriction, more distinct of decline; however, the root activity of CK reached the peak at prosperous fruiting stage. Leaf and stem nitrogen content of cucumber decreased because of root restriction, but phosphorous and potassium content are in the contrary. Root volume and absorption area of organic culture cucumber decreased withthe increase of root restriction degree, but the diversity between 4L treatment and CK are small. Soluble sugar and starch content of cucumber leaves increased with the decrease of rooting-zone volume, it indicated that root restriction enhanced the carbohydrate allocation ratio in cucumber leaves.3. Fruits dry matter content increased because of rooting-zone volume restriction, but nitrate content decreased. Fruits quality of 12L and 8L treatments has little difference, while soluble sugar, soluble protein, vitamin C content decreased in 4L treatment, it indicated that extremely root restriction could decrease fruits quality. Early yield of cucumber increased as rooting-zone volume restriction. In spring stubble, yield per plant of 4L treatment decreased obviously after 79d of setting, but yield per plant of 8L treatment had no distinct difference with CK and 12L treatment; so we can use 8L rooting-zone volume to produce early ripe cucumber in spring. In fall stubble, yield per plant had no evident difference among four treatments after 79d of setting; therefore, 4L rooting-zone volume can satisfy the solar greenhouse cucumber cultivation demand. 4.Substrate compositions had minor effect on cucumber which rooting-zone volume is 8L, but 8L rooting-zone volume treatments had evident difference with 4L treatment. In the precondition of sufficient nutrition supply, although rooting-zone nutrition has a little effect on growth and development of cucumber, it cannot fundamentally amend the influence of root restriction.