Effects Of Different Mulching Methods And Nitrogen Levels On Vegetative Growth And Fruit Quality Of Apple Trees

The Loess Plateau is the optimum region of apple in China,where the temperature difference between day and night is large and the illumination is abundant.However,Its disadvantages will reduce the economic effects of apple,which have the small amount of precipitation and uneven spatial and temporal distribution,coupled with severe soil erosion.In this experiment,the dwarfing apple in Weibei dry land of Shaanxi Province was taken as the research object.Through field observation and indoor analysis,this thesis discussed the different mulching treatments and different nitrogen levels on tree growth and the quality of fruit,analyzed the growth and development of fruit tree roots and the relationship between tree growth and quality of fruit,and provided the basis for the fertilizer management under the mulching.The main results are as follows:1.Mulching improved the physiological characteristics of leaves,including the leaf area,chlorophyll content,leaf nitrate reductase activity and Leaf nutrient elements,and reduced the proportion of long shoots,meanwhile increased the length of shoot,medium short shoot proportion,trunk and branches thickness proportion,and then improved the branch group structure.Among them,the best treatment effect is double mulching;Nitrogen rates also improved the physiological characteristics of leaves,Including the leaf area,chlorophyll content,leaf nitrate reductase activity and Leaf nutrient elements,meanwhile promoted the formation of tree branches,increased shoot length and the proportion of long shoots,reduced trunk thickness.Among them,the effect of low and medium nitrogen treatment(0.25 ~ 0.5kg/plant)was the most conspicuous,and high nitrogen treatment can produce inhibitory effects.2.Mulching affected the flowering of trees,increased significantly fruit yield,fruit weight,vertical and horizontal diameter,sugar-acid ratio,content of vitamin C and K element.Meanwhile,improved the partial factor productivity of fertilizer(PFP)and nitrogen fertilizer(PFPN),and promoted the transformation of the fruit's starch into sugar.The efficiency is more significant with double mulching;Nitrogen application promoted flower bud differentiation,improved fruit quality and yield,and delayed the starch conversion of fruit.The effect of low and medium nitrogen treatment(0.25~0.5kg/plant)was the most conspicuous.However,the middle and high nitrogen treatments(0.5~0.75kg/plant)significantly reduced PFP and PFPN,therefore,excessive nitrogen application would lead to the waste of nitrogen fertilizer,which had the most economic effects on low nitrogen treatment(0.25kg/plant).3.Correlation analysis showed that apple tree vigor and branch group structure are strong related with root length,root activity,root surface area,root active absorption area,root biomass,root morphology,physiological parameters in the 0 ~ 60 cm soil layer?It can be fund that mulching affects the growth and root activity of root system from 0 to 60 cm by regulating the soil environment of orchard,thus affecting the growth and development of tree and fruit quality.Therefore,the fertilization technique for drought resistance and high yield in apple,dual mulching for straw + row grass or + row grass binding nitrogen levels(0.25~0.5kg/ plant),was reconmmended as an efficient farming technique and had an important application prospect production in the dry land of Loess Plateau.