Study On The Cultivation Of Strong Seedlings And Nutrient Management Mode Of Cucumber In Substrate Cultivation

The interaction of environmental conditions such as temperature,humidity and illumination are important factors leading to overgrowth of cucumbers seedlings,and they are also important reasons for seriously affecting the quality of seedlings in plug trays.In this study,the effects of different CCC application methods and irrigation water temperature treatments on the development of seedlings in cucumber cavity trays were compared and analyzed,and the effects of different nutrient management modes on the growth of cucumber seedlings,salt accumulation in the root zone and the microbial community in the root zone were explored,with a view to screening out the best control method for cucumber seedlings in cavity trays and the nutrient management mode for cucumber cultivation with high water and fertilizer utilization efficiency.The research results are as follows:1、The results showed that both the application of CCC and the reduction of irrigation water temperature significantly reduced the plant height of seedlings.Under the irrigation water temperature of 10℃,the strong seedling index was increased by 45.61%compared with the spraying treatment.Under the same CCC application method,lowering the irrigation water temperature could inhibit the growth of cucumber seedlings to a certain extent,but it would reduce the SPAD value of the leaves and cause some damage to the leaves.In a comprehensive analysis,the treatment of CCC concentration of 200 mg·L^-1,irrigation with water and irrigation water temperature of 22℃can effectively inhibit the growth of cucumber seedlings,and the best effect of seedling strengthening,which is a suitable control measure for cucumber seedling strengthening.2、Under closed system,the single plant yield was increased by 2.46%,5.31%and9.00%,respectively,in the 3 d change of nutrient solution treatment（T1）compared to the other treatments.The closed system yield was 25.80%lower than open system.During the whole growth period,the EC value of cucumber root region increased with the prolong of growth period.The contents of total nitrogen,total phosphorus,Ca²⁺and Mg²⁺in the root zone solution of open system（CK）increased with time,while K⁺remained at a relatively stable level.In the closed system（T4）,the contents of total nitrogen and K⁺decrease with time,while the contents of total phosphorus and Ca²⁺increase first and then decrease,while the content of Mg²⁺increases.With the prolongation of growth period,the imbalance of ion ratio in closed system becomes more and more serious,and with the decrease of nutrient solution replacement frequency,the imbalance of ion ratio becomes more and more serious.In a comprehensive analysis,the nutrient solution change once every 5 d is the suitable nutrient solution management mode for closed system,which has the best production efficiency.3、The abundance and diversity of microorganisms in the inorganic substrate were influenced by the EC value,and the abundance and diversity of bacterial communities in the root zone were higher in the open system than in the closed one,while the abundance and diversity of fungal communities in the root zone were higher in the closed system than in the open one.Among them,the highest bacterial richness in the root zone was found in the 7 d nutrient solution change treatment,and the highest fungal richness was found in the open system and replace nutrient solution when exhausted treatment;while the highest bacterial and fungal diversity was found in the 5 d nutrient solution change treatment.Mineral nutrients N,K and Ca were correlated with bacterial community abundance in the root zone,especially K.The effects of each environmental factor on the composition of fungal communities in the root zone were not significantly different.