Study On Different Cropping Patterns Of Cucumber Cultivated In Green House And Its Mechanism Of Repairing Soils

With the continuous development of vegetable production, the problem of continuously cropping obstacles is more and more serious, and it has become one of the major factors of restricting sustainable development.Thus, it is imminent to solve the problem of continuous cropping obstacles . It is exactly effective ways and measures for Mixed intercropping, crop rotation and the development and application of soil remediation agents to solve this problem.In this study, the cucumber crop was selected to be as the research object, which was larger to be cultivated and even intolerance to continuous cropping obstacles in protected vegetables; Chemical Ecology theory - Allelopathy was as guidance, the methods of molecular biology techniques-DGGE was as a means, the inter-relationship between inter-cropping crops (companion crop) - soil - the main crops was as the main line, six items of studies had been carried out, such as the impacts for different inter-cropping patterns on cucumber growth and soil environments, the impacts for different crop root exudates on cucumber seedling growth and soil environment, the impacts for different crop stubbles on cucumber growth and soil environments, the allelopathic effects for different crop root exudates on cucumber seed germination and the Fusarium and the GC-MS analysis of different crop root exudates, the allelopathic effects for the decomposition material of different crop stubbles on cucumber seed germination and the Fusarium and the GC-MS analysis of the decomposition material of different crop stubbles, the repairing effects for the complex mixture of wheat root exudates and stubble decomposition material on continuously cropping soils and so on, to try to clarify the close relationship between the inter-crop (companion crop ) - soil - the main crop, and to explore the mechanism of repairing soil, some progresses had been made, the main results were as follows:1. The impacts for different inter-cropping patterns on cucumber growth and soil environment.In this study, wheat, soybeans, oats were selected to intercrop with cucumber, to explore the effects for different inter-cropping patterns on cucumber growth and soil environment. The results showed that: the three inter-cropping patterns decreased significantly soil bulk density, and increased total porosity of soil; each treatment significantly reduced the accumulation of soil salinity within the entire growth period, the treatment of wheat-cucumber had the biggest drop of the EC in later growth period, dropped 38.96% compared to the control; the organic matter contents of cucumber-wheat and cucumber-soybean were significantly higher than control; the treatments significantly improved the composition of microbial flora, increased the number of bacteria and actinomycetes, reduced the number of soil-borne pathogens; the treatment of cucumber-wheat dropped the number of Fusarium oxysporum by an average of 69.44%; each treatment significantly promoted the growth of cucumber and improved production, the treatment of cucumber-wheat had the best combined effects on mitigation to continuously cropping soil., reached for the purpose of easing the continuously cropping soils.2. The impacts for different crop root exudates on cucumber seedling growth and soil environments.The10×15cm nutrition bowls larger were selected to use for loading the 500g soil of continuously cropping cucumber, the broadcast method was selected to use for sowing the seeds of cucumber. three concentrations of wheat, soybean and oat root exudates were irrigated into the soil of continuously cropping cucumber, , the effects were studied for the root exudates of three crops and different concentrations on the soil environments and the growth of cucumber seedlings. Our results showed that the root exudates of three crops decreased significantly soil bulk density, and increased total porosity of soil; each treatment significantly reduced the accumulation of soil salinity within the entire growth period, the treatment of wheat-cucumber had the biggest drop of the EC in later growth period ; the organic matter contents of cucumber-wheat and cucumber-soybean were significantly higher than control; the treatments significantly improved the composition of microbial flora, increased the number of bacteria and actinomycetes, reduced the number of soil-borne pathogens; wheat root exudates on high concentrations were in favor of increasing the number of bacterial species and decreasing of fungal species in the soil;100% concentration of wheat root exudates significantly promoted the growth of cucumber seedlings.3. The impacts for different crop stubbles on cucumber growth and soil nvironments.By pot experiments, the crop stubbles of wheat, soybean and oat had been applied the soil of continuously cropping cucumber by the amounts of 0.5%, 1% and 2% (Note: oat stubble only by 0.5% of consumption) , we studied the effect of different crop stubbles and different amounts of stubbles on the soil of continuously cropping cucumber. The results showed that the three crop stubbles decreased significantly soil bulk density, and increased total porosity of soil; each treatment significantly reduced the accumulation of soil salinity within the entire growth period, the treatment of 2% of wheat stubble had the biggest drop of the pH in later growth period ; the organic matter contents of most of the treatments were significantly higher than control; the three crop stubbles of significantly improved the composition of microbial flora, increased the number of bacteria and actinomycetes, reduced the number of soil-borne pathogens; the treatment of 2% of wheat stubble significantly promoted the growth of cucumber and improved production, the output was increased 34.23 percent compared to the control.4. The allelopathic effects for different crop root exudates on cucumber seed germination and the Fusarium and the GC-MS analysis of different crop root exudates.In this test, we studied the allelopathic effects for different crop root exudates on cucumber seed germination and the Fusarium and made the GC-MS analysis of different crop root exudates.The results showed that the three types of root exudates had different allelopathic effects on cucumber seed germination. High concentrations of root exudates from wheat promoted cucumber seed germination, whereas low concentrations inhibited it. A similar pattern was observed among exudates from soybean, but the opposite trend was observed using exudates from oat roots. The three types of root exudates also had different effects on cucumber seedling growth. The integrated allelopathy index (RI) showed that most root exudates promoted seedling growth. Only the 100% concentration of oat root exudates inhibited seedling growth. Compared with the other treatments and the control, the 50% concentration of wheat root exudates showed the strongest growth promotion effect (RI = 3.333), followed by the 100% concentration of wheat root exudates (RI = 2.488). Our results showed that higher concentrations of wheat root exudates positively affected cucumber seed germination and seedling growth.GC-MS analysis showed that the CH2Cl2 extracts of wheat root exudates mainly included hydrocarbons, amines, esters, amides, ketones and other substances, these substances had very different content levels, one of 2,3-Dimethoxyamphetamine (2 , 3 - dimethoxy-amphetamine) was the highest, reaching 23.70 percent, followed by 3-Ethoxyamphetamine (3 - ethoxy-amphetamine), the content reached 13.16%, other substances were very low in root exudates.The amine and amide of these substances also reported in the literature uncommon.5. The allelopathic effects for the decomposition material of different crop stubbles on cucumber seed germination and the Fusarium and the GC-MS analysis of the decomposition material of different crop stubbles.In this test, we studied the allelopathic effects for different crop root exudates on cucumber seed germination ,seedling growth and the Fusarium and made the GC-MS analysis of different crop root exudates.The results showed that the three decomposition materials of crop stubbles had different allelopathic effects on cucumber seed germination and seedling growth. Decomposition of wheat stubble significantly increased cucumber seed germination rate, Whether in high or low concentrations, decomposition materials of wheat promoted cucumber seed germination, high concentrations of decomposition materials of wheat promoted greatly, low concentration promoted the role of small. soybean stubble decomposition significantly improved cucumber.seed germination rate, and along with lower concentration, promoted role increased; oat stubble decomposition significantly inhibited germination of cucumber seeds in high concentration, the higher the concentration, the stronger the inhibition. Three decompositions of crop stubbles had significant impacts on the growth of Fusarium colonies.GC-MS analysis showed that the CH2Cl2 extracts of wheat stubble decomposition mainly included phenols, amines, alcohols, amides, aldehydes, esters and other substances, these substances had very different content levels, one of 3-Ethoxyamphetamine (3 - ethoxy-amphetamine) was the highest, reaching 34.34 percent, followed by 1,3-Dioxolane-4-methanol (1,3 - dioxo-pentane -4 - methanol) and 3-Methoxyamphetamine (3 - methoxy-amphetamine), the contents reached 27.53% and 26.28%, other substances were very low, the amine and amide of these substances also reported in the literature uncommon.6. The repairing effects for the complex mixture of wheat root exudates and stubble decomposition material on continuously cropping soils.In this study, we first selected wheat crop in accordance with chemical ecology theory (allelopathy), and substantially extracted the root exudates and stubble decomposition of wheat crop as the main components of soil remediation agent, used advanced molecular biology techniques and methods to make scientific complex. The results showed that the different mixtures had different restorations of role on the soil, the treatment of STP2 was best, the mixture could effectively improve the community structure of rhizosphere microbial diversity, improve soil physical and chemical properties, improve the utilization of soil nutrients, dropped cucumber blight disease index by 78.21 percent, reduced the value of soil EC by 47.73%, at the same time,it could improve soil organic matter content, increase soil moisture, and promote the growth of the cucumber.