Effects Of 26 Continuous Cropping Rounds Of Cucumber On Medium Elements And Trace Elements Of Soil And Plant In Solar Greenhouse

With the specialization and intensive development of facility vegetable industry in China,the obstacle of continuous cropping of facility soil is becoming more and more serious,which has become the main limiting factor of sustainable development of facility vegetable production.Cucumber is one of the main vegetable crops in protected cultivation in China.At present,the effects of long-term continuous cropping of protected vegetables on soil and plant medium elements and trace elements are not clear.Therefore,this experiment took’Jinyou 30’cucumber as experimental material to study the effects of 2～26 continuous cropping of cucumber on the contents of medium elements and trace elements in plant and soil in solar greenhouse,and to clarify the variation characteristics of medium elements and trace elements in soil,as well as the absorption and distribution characteristics of medium elements and trace elements in cucumber plant,so as to provide theoretical basis for the scientific fertilization of vegetables and the study of soil obstacles in solar greenhouse.The main results are as follows:1.With the increase of continuous cropping,the plant height increased first,then decreased,and then increased.However,there were no significant differences in plant biomass,yield and soil p H except for individual stubble.The soil p H value varied from 6.77to 7.03,and there was no acidification.The EC value of soil increased first and then decreased,and reached the highest in the 16th crop.The content of available N,available P and organic matter increased gradually.Compared with the second crop,the 26th crop increased by 59.12%,34.55%and 26.17%respectively,while the content of available K decreased slightly.2.The content of soil exchangeable Ca fluctuated from 703.54～833.75mg·kg^-1in 2～26cucumber continuous cropping.The content of total Ca increased significantly,resulting in a significant decrease in the proportion of exchangeable Ca in total Ca,which decreased by53.23%compared with the second crop.Compared with the second crop,the content of exchangeable Mg in the 26th crop decreased by 25.77%,but the content varied from220.32～312.44mg·kg^-1.The proportion of exchangeable Mg in total Mg decreased slightly.3.The contents of available Fe,Mn,Cu,Zn,B and Mo in soil were significantly affected by 26 continuous cropping times.The content of available Fe increased gradually and decreased gradually after the 16th crop reached the highest level.The content of available Fe varied from 29.87～53.87mg·kg^-1.The content of available Mn increased gradually in the second to the 12th crop,and reached the highest level in the 12th crop,and then fluctuated.The content of available Mn ranged from 13.20～33.50mg·kg^-1.The content of available Cu increased gradually in the 12th stubble and then decreased gradually.The content of available Zn increased by 87.35%in the 26th crop compared with that in the second crop.The content of available B was at the middle level in the middle stage of continuous cropping,and the rest were in a relatively lack state.The content of available Mo increased by 221.42%in the 26th crop compared with the second crop.Except for the early stage of continuous cropping.4.The correlation analysis showed that the soil alkaline N,available P,organic matter,available Zn,available Mo,total N,total P,total Ca were positively correlated with successive cropping.The effective copper in soil was positively correlated with the successive cropping.The soil exchangeable Mg,total Fe and total Mn were negatively correlated with the successive cropping.The total Zn in soil was negatively correlated with the successive cropping.The main component analysis of continuous cropping soil and plant growth was carried out.After comprehensive evaluation,it was found that the 18th crop had the highest comprehensive score and the second lowest,and the change characteristics of each 6 crops would rise first and then decrease at the beginning of the 8th crop.5.The correlation analysis of continuous cropping crops and plant nutrient accumulation showed that there was a significant positive correlation between total P accumulation and continuous cropping crops,a significant negative correlation between total Mo accumulation and continuous cropping crops,a significant negative correlation between total B accumulation and continuous cropping crops;at the same time,plant N,K,Ca,Mg,Fe,Mn,Cu,B accumulation was fluctuating as a whole change.The accumulation of P and Zn showed a trend of first increasing and then decreasing.The Mo accumulation of the whole plant showed no significant difference except for individual crops.In addition,the accumulation of nutrient elements was mainly concentrated in leaves and fruits,while stem and root only accounted for a small part of them.In conclusion,the long-term continuous cropping of cucumber in solar greenhouse will affect the plant growth,yield,soil nutrient content and the proportion of nutrient elements.With the increase of continuous cropping,the comprehensive level of soil and plant will increase and then decrease every six crops as a cycle,which also affects the absorption of nutrient content and the distribution of nutrients in plants distribution.