Effects Of Controlled-release Urea And Urea Dosage On Growth And Soil Microenvironment Of Oriental Melon

At present,problems such as lower vegetable quality and yield,excessive nitrate content,waste of resources and pollution of the ecological environment caused by the abuse of nitrogen fertilizer in vegetable production are becoming more and more serious.Reasonable nitrogen application has become a research hotspot for scholars,and in recent years,with the emergence of new fertilizers and its application and development in production,whether it can effectively replace the traditional fertilizer to achieve the amount of fertilizer reduce and increase the efficiency is worth our study.This paper chooses the oriental melon ‘Yumeiren' as test material,and sets nine treatments on the basis of soil testing and formulated fertilization,including a non-nitrogen control(CK),50%urea(T1),50% controlled-release urea(T2),50%urea + bio-fertilizer(T3),50%controlled-release urea + bio-fertilizer(T4),30%controlled-release urea +20% urea + bio-fertilizer(T5),100%urea(T6),100% controlled-release urea(T7),150%urea(T8).The effects of different treatments on plant growth,nitrogen uptake,fruit yield,quality and microbial functional diversity of oriental melon were determined.The results were described as follow:1.Plant height,diameter and leaf number of oriental melon went up with the increase of nitrogen level during the vegetative growth period,while the fertilizer application with the biological fertilizer treatment(T3~T5)showed some advantages.And growth indicators of T3 treatment were all significantly higher than other treatments at the early stage of reproductive growth.However,the excessive application of nitrogen fertilizer(T8)inhibited the growth of plants,and the fresh weight and total dry matter accumulation of each plant showed a tendency to increase first and then decrease as the amount of nitrogen applied at fruit maturity.Under the same nitrogen application level,the total chlorophyll content of the top three leaves of the melons treated with common urea(T1,T3,T6,T8)was significantly higher than that of the controlled-release urea(T2,T4,T7).2.When the amount of nitrogen applied increased,the amount of nitrogen uptake was also increased at the fruit expanding stage,and the uptake of nitrogen,phosphorus and potassium in each plant was increased first and then decreased with the increase of nitrogen application in the mature period.The nutrient accumulation and distribution of organs showed as follows: fruit> leaf> stem> root.In terms of soil nutrients,the content of available N in the soil was significantly positively correlated with the amount of nitrogen applied,but there was no significant difference between the same level of nitrogen application.In the 50% reduction N application,the differences in total N,available P,and available K between the reducedand controlled-release nitrogen fertilizer combined with the application of bio-fertilizer treatment(T4)and the 100% nitrogen treatment(T6 and T7)were not significant.3.Under the 100% nitrogen application level,the yield of single plant of melon under controlled release urea treatment(T7)was significantly higher than that of normal urea treatment(T6).And compared with the T7 treatment,the yield per plant of the reduced nitrogen application(T3 and T4)did not decrease significantly,but increased.With the increase of nitrogen application rate,apparent utilization rate of nitrogen fertilizer and agronomic efficiency were significantly reduced,and the difference between T1~T4 treatment and appropriate(100%)and excess(150%)nitrogen application treatments reached significant levels.The more significant are T3 and T4.4.Compared with 100% nitrogen application,the reduced nitrogen application did not significantly affect the quality of ripe melon fruits.The content of soluble sugar,VC and aroma of 50% controlled-release urea combined with biofertilizer treatment(T4)were both higher than other treatments.At the same time,the content of nitrate in fruits treated with T4 was the lowest,which was only 162.38 mg/kg.5.Compared with the application of normal urea treatment,the AWCD values of applied controlled-release urea treatment(T2,T4,T5,T7)were higher,and T4 treatment had the highest utilization of the six kinds of carbon sources.And its diversity index was significantly higher than 150% nitrogen treatment(T8).In addition,soil urease,catalase,and FDA hydrolase activity of T4 treatment was highest in all treatments and significantly higher than T8 treatment.Taken together: reducing nitrogen fertilizer combined with bio-fertilizer can help to promote the growth of melon,improve the quality of ripe melon fruit,increase the yield of single melon and improve the soil microbial activity,in which the 50%controlled-release urea and the application of bio-fertilizer have better performance.