Responses Of Leaf Traits,Soil Nutrients And Fruit Quality Of Zizyphus Jujuba Mill.cv ’Lingwuchangzao’ To Nitrogen Application

Zizyphus jujuba Mill.cv ’Lingwuchangzao’ is one of the excellent characteristic economic tree species in Ningxia.As an excellent fresh jujube variety,it is very popular among consumers.However,due to the unreasonable application of nitrogen fertilizer in ’Lingwuchangzao’ field,it has caused a series of environmental pollution and food safety problems.Nitrogen application has become a key factor restricting the yield and quality of ’Lingwuchangzao’.In response to the above problems,this study took 7-8 years old grafted ’Lingwuchangzao’(rootstock is Zizyphus jujuba Mill.var.spinosa(Bunge)Hu ex H.F.Chow)as materials,and treated CK(nitrogen application rate 0kg/hm2),N1(nitrogen application rate 150kg/hm2),N2(nitrogen application rate of 300kg/hm2),N3(nitrogen application rate of 450kg/hm2),N4(nitrogen application rate of 600kg/hm2),study the leaf characteristics,soil nutrients and fruit quality annual cycle of ’Lingwuchangzao’ under different nitrogen application rates Change the law,explore the response law of leaf traits,soil nutrient and fruit quality of ’Lingwuchangzao’ to nitrogen application,establish the relationship between leaf properties,soil nutrient and fruit quality,and provide theoretical support and technical guidance for fertilization of’Lingwuchangzao’,And provide a stable foundation for the development of related research.The main findings are as follows:(1)’Lingwuchangzao’ hanging and chlorophyll content have a sharp increase in the fruit expansion stage-fruit white maturity stage;the total nitrogen content of the leaves is maintained at 0.97%-1.99%throughout the entire period.During the growth period,there is roughly a downward trend;the total phosphorus content of leaves is maintained at 0.11%-0.66%,and the total potassium content of the leaves is maintained at 0.79%-4.14%and fluctuates throughout the growth period.Larger,there is a clear upward trend in the total potassium content of leaves during the period from the coloring period to the mature period.(2)The total nitrogen content of the soil is maintained at 0.03%-0.18%during the entire growth period,which first rises and then decreases,reaching the peak in the white maturity period;the soil available phosphorus content is maintained at 2.07-144.9mg/kg,and the change trend is mostly as follows "W",reached the valley value during the fruit expansion and coloring period.After the white maturity period,the soil available phosphorus content of ’Lingwuchangzao’ decreased significantly.At this stage,’Lingwuchangzao’ has a high demand for phosphate fertilizer and should be supplemented in time;The content of available potassium is maintained at 64.57-847mg/kg,which is expressed as "W",reaching the valley value in the young fruit stage and the coloring stage.(3)Fruit longitudinal diameter,transverse diameter,single fruit weight and fruit soluble sugar content showed an upward trend during the main phenological period;fruit organic acid showed a downward trend and then upward trend;fruit Vc content showed a downward trend.(4)The comprehensive performance of ’Lingwuchangzao’leaf traits,soil nutrients and fruit quality under different nitrogen treatments is:N2(nitrogen application rate of 300kg/hm2)>N4(nitrogen application rate of 600kg/hm2)>N3(nitrogen application rate of 450kg/hm2)>N1(nitrogen application rate 150kg/hm2)>CK(nitrogen application rate Okg/hm2).(5)When the nitrogen application rate is 300kg/hm2,the leaf total phosphorus,fruit transverse diameter,single fruit weight,fruit soluble sugar content,and fruit Vc content of ’Lingwuchangzao’ at maturity are increased by 41.6%,8.4%,16%,respectively compared with CK.3.6%,16.9%.At the same time,the organic acid content of the fruit is 6.3%lower than that of CK.The amount of nitrogen application can significantly increase the quality of‘Lingwuchangzao’,and it can be popularized in Lingwu area.(6)The total nitrogen content of soil and the total nitrogen content of the leaves of’Lingwuchangzao’ in the young fruit stage,white maturity stage and mature stage are all significantly positively correlated.The synergistic effect between soil nitrogen and leaf nitrogen is very obvious;leaf traits at each stage,The effect of soil nutrients on the promotion of fruit quality is greater than the inhibition.Fertilization is crucial to the formation of good fruit quality of‘Lingwuchangzao’.