Studies On The Key Technology Of Nutrient Solution Seedling Of Cucumbers

Cucumber (Cucumis sativus L.) is one of the important vegetable crops widely cultivated all around the world. Cucumber seedling transplantation was mainly used in production, so seedlings require ideal environmental conditions and higher technology; therefore,. At present, a widespread use of factory plug seedlings realized factory production and commercialization of the supply of vegetable seedlings; however, there were still some problems such as:the small nutrition volume, fertilizer and water difficult to precisely control, matrix ratio difficult to grasp. To solve these problems, the Beijing Vegetable Research Center developed a new type of nutrient solution seedling system. In the system, we got rid of the limitation of plug seedling substrate, and a nutrient solution seedling factory similar to plant factory was established with the nutrient solution as the medium to cultivate the seedlings, and the temperature, oxygen, nutrients and other environmental factors during the breeding process could precisely regulated. The nutrient solution culture technique was applied in cucumber seedling and the seedling system of cucumber nutrient solution was established which could provide a reference for other vegetables without matrix nutrient solution nursery. The main findings are as follows:1. This paper compared the effects of two seedling-raising methods on the growth and development of cucumber. Cucumber cultivars were ’Lu Bo No.6F1’(summer) and ’Zhong Nong No.26’(spring and winter). The results indicated that, compared with substrate seedling, nutrient solution seedling has totally changed the ways of supplying water and nutrient to seedlings, meanwhile the germination rate, plant height, stem diameter, cotyledon size, leaf size, dry weight and seedling index of nutrient solution seedlings were significantly higher. After transplanting, the plant morphology was significantly different from those of substrate seedlings. Compared with the substrate seedlings, nutrient solution seedlings were significantly changed, specifically the early blooming period advanced4d, the average pod number per plant, yield per plant, and periods yield per unit area increased by36.7%,33.0%,60.3%and19.0%. It suggested that nutrient solution seedling significantly increased the germination rate, biomass accumulation, seedling index and the yield of cucumber after transplanting than substrate seedling.2.’Zhong Nong No.26’was used as test material to study effects of different nutrition solution concentrations on the growth of cucumber seedlings under nutrient solution seedling. The results showed that the seedling had lower plant height, thinner stem diameter, lower biomass, weaker resistance, lower root volume and seedling index in lower concentration treatment (0.5and1.0times nutrition solution). Under higher concentration (2.0times nutrition solution) treatment, the growth of the seedlings was inhibited during the earlier growing stage, although the growth speed was accelerated in the late growth stage, the seedling index was lower, In1.5times nutrition solution treatment, the plant had a relatively reasonable performance, presenting good promoting effects such as better biomass, seedling index, root activity, growth rate and resistance. Therefore,1.5times nutrition solution is the optimal concentration for nutrient solution seedling culture without substrate.3. Cucumber cultivar’Lu Bo No.6F1’ was used to study the effects of different ways of oxygen supply on the growth of cucumber seedlings under nutrient solution seedling. The results showed that the growth of cucumber seedlings was significantly better in recycling treatments (7.5cm and6.0cm) than the hydrostatic treatments (7.5cm and6.0cm), but no significant difference with the control (CK). Compared to the control (CK), no significant difference was observed on the photosynthetic pigment content and photosynthetic activity of seedlings in the recycling treatments (7.5cm and6.0cm) and hydrostatic treatment (7.5cm), moreover, the above indexes in the hydrostatic treatment (6.0cm) was significantly lower than the control. There was no significant difference on root activity among all the treatments. Therefore, the recycling treatments (6.0-7.5cm) and hydrostatic treatment (7.5cm) were better choice in cucumber nutrient solution seedling.4. Cucumber cultivar’Lu Bo No.6F1’ was used to study the effects of rhizosphere cooling on the growth of cucumber seedlings in nutrient solution seedling in summer. The result was showed that:compared to the normal treatment, the temperature reduced7℃in the nutrient solution under cooling treatment, which the plant height, hypocotyl length significantly decreased by11.0%and10.6%, and reduced the formation of leggy seedlings. As the temperature was more suitable in the cooling treatment, stem diameter, cotyledon area, true leaf area, fresh weight, dry weight, seedling quality index, root volume, chlorophyll a and total chlorophyll content in the leaf were significantly higher than the normal treatment. Rhizosphere cooling treatment promoted growth significantly in the later growth stage but little in the early stage. Therefore, the treatment of rhizosphere cooling is entirely feasible in nutrient solution seedling, and could reduce leggy seedlings in summer.’Zhong Nong No.26’ was used as test material to study the effects of rhizosphere heating on the growth of cucumber seedlings in nutrient solution seedling in winter. The results showed that the heating treatment increased the temperature of nutrient solution, promoted the growth of seedlings. Dry matter, seedling index, photosynthetic capacity were significantly enhanced, but the growth of root was slowed, the root-shoot ratio was reduced. All in all, the treatment of rhizosphere heating is entirely feasible in nutrient solution seedling in winter.