Effects On Growth,Yield And Nuts Quality Of Walnuts From Different Fertilizer Treatment

The cultivation history of walnut is long in China, which is widely distributed and deeply recognized for its nutrition. The prospects for developing of high-quality walnut economy in the future is hopeful and broad, because the current domestic walnut production and market is far to no space. However, in the actual production process of walnut, there are some factors seriously affected the walnut yield and quality; for instance, improper fertilization, pest breeding, extreme climate and mismanagement. What’s more, the excessive using of chemical fertilizers and pesticides have caused great harm to the development of walnut industry, even generated severe problems on the ecological environment and food safety, such as land compaction, soil depletion, groundwater contamination, chemical fertilizers and pesticides enrichment. The current study is to fully develop the ecological and economic benefits of walnut trees by improving the traditional fertilization method.In order to understand the effect of combined application of various fertilizers on walnut phenophase growth, yield and nut quality, the young and mature ‘Xiangling’ walnut trees were used as experimental materials with the method of randomized block fertilization. The main research were seven parts and showed as follows,(1) Phenophase observation: leaf(germination, bud cracking, leaf-expansion), male flowers(the initial stage, the flower stage and the end stage), female flowers(the initial stage, the flower stage and the end stage) as well as the pollination period;(2) Growth survey: length and diameter of new shoots, growth of trunk circumference, leaf area;(3) Leaf nutrient element measurement: nitrogen, phosphorus, potassium, calcium;(4) Fruit index: fresh fruit weight, dried fruit weight, kernel weight, peel rate, kernel yield and oil yield;(5) Oil component analysis: linoleic acid, oleic acid, linolenic acid, palmitic acid, palmitoleic acid, stearic acid;(6) Kernel protein content determination;(7) Kernel trace elements measurement: calcium, iron, zinc, potassium, phosphorus.Based on the comprehensive analysis of the experimental results, preliminary conclusions were drawn as follows:(1) The application of a variety of fertilizers can prolong the duration of male and female flowers, can effectively improve the effective pollination and fruit setting rate and generate positive effect on the quality and yield of walnut.(2) Combination application of various fertilizers is conducive to the growth of ‘Xiangling’ walnut trees. The effects generated by combination application of various fertilizers on the young walnut trees were more obvious than on that of the mature ones. The length and diameter of new shoot growth were increased by 7.17% and 11.2% compared with that of the control(no fertilizer treatment, CK1), respectively.(3) Mixed use of various fertilizers can promote the absorption of trace elements in ‘Xiangling’ walnut trees, among which the effect created by usingbio-organic fertilizer is more significant than others. For the mature trees, simultaneous application of chemical, bio-organic and organic fertilizers(T3) make themselves posses higher content of N(0.740%), P(0.033%), K(0.506%) and Ca(1.601%) than only application of the chemical fertilizer(CK).(4) The application of a variety of fertilizers can improve the quality of ‘Xiangling’ walnut with reduced peel rate, thin shell, big nut, and delicious texture. The yield increasing effect of the young walnut tree was more significant than the mature ones, which was 142% of that generated in 2015. The application of organic fertilizer showed a obvious effect on increasing the kernel yield, but the application of bio-organic fertilizer is helpful to increase the oil content of walnut kernel. For the young tree, combined application of chemical, bio-organic and organic fertilizer(T3) make themselves posses higher content of kernel yield(1.66%) and oil yield(2.59%) than those of the trees treated by no fertilizer(CK1).(5) The content of unsaturated fatty acids, protein and trace elements of the ‘Xiangling’ walnut were affected by applying various fertilizers. The linoleic acid content of ‘Xiangling’ walnut oil under combinating application of chemical fertilizer and bio-organic fertilizer treatment(T2) was 2.46% higher than that under only application of chemical fertilizer treatment(CK). The protein content of ‘Xiangling’ walnut under T3 treatment was 2.85% higher than that under CK.In conclusion, combined application of the chemical fertilizer, organic fertilizer and bio-organic fertilizer can improve the nutrient composition of the soil, can promote the absorption of nutrients, can be benefit for the expansion the crown of walnut trees, meanwhlie, can advance the nut yield and quality.