The Study Of Returning Apple Branches Degradation And Their Effect On Soil And The Respiratory Metabolism Of Root-stock

Fruit tree branches are rich in organic matter and various inorganic nutrients,such as cellulose,lignin,protein,carbohydrate,and fat,are valuable agricultural resources.It is estimated that the area of apple cultivation in China is 2.5 million hectares.Many of the shoots pruned each year are abandoned,resulting in the waste of resources.Abandoned apple shoots were used as returning materials,the closely relationship of "branches-soil-roots" in apple orchard was studied in this research.Through analyzing the changes of structure and nutrient in apple branches and soil quality,and comparing the effects of dynamic soil environment on root behavior,this paper evaluated the ecophysiological effect of apple shoots returning in orchard and provide theoretical basis for the recycle of biological resources in the field of fruit cultivation.Main research results are as follows:1.Observation and analysis technologies such as Scanning electron microscope(SEM),X-ray diffraction,Fourier transform infrared spectroscopy(FTIR)were used to study the degradation of apple branches.It was found that cellulose content in shoots significantly reduced after being returned for 3 year,decreased from 39.04%to 9.71%,the molecular structure of lignin were destroyed,chemical bonds were ruptured,and the plasmodesmata were depredated,cell wall structure for supporting was also damaged after three-year returning.Plant residues of the nutrients were released back into the soil.The relative contents of P,K and Ca declined 34.12%,39.44%,and 27.90%respectively.For degradation of lignin the screening and identification of microbes showed that the important lignin degradation microbial is a kind of Trichoderma.2.Branches returning can stabilize soil temperature,improve soil moisture,and then improve the physical properties of soil.Principal component analysis,Pearson correlation analysis and soil quality index(SQI)comprehensive analysis methods,combined with fuzzy mathematics,were adopted to evaluate the effects of returning apple branches on comprehensive soil quality.The results showed that abandoned apple branches returning had a significant effect on soil quality in top layer,which was increased by 8.75%compared with the control,although no obvious pattern of change was observed in the 20-40 cm soil layer.Over time,plant-residue degradation played a crucial role in improving soil chemical properties of soil quality.Humification of apple shoots in the soil,enhanced the soil microbial activity,and improved the ability of soil microorganism using different carbon sources.At the same time,it rose the function diversity of soil microbial community,which was conducive to the stability of soil ecosystem.3.With the extension of branches returning time,glycosides contents in the soil were accumulated,and the average growth of 0-20 cm soil layer reached 3.24 mg-kg-1 while the average annual variation of 20-40 cm was 1.16 mg·kg-1.The increasing contents caused no obvious damage to the apple plants enter the stage of harvest.Simulation concentration to process seedlings,root glycosides worsened during the increasing of concentration in the plant rhizosphere environment,root cell antioxidant enzyme system crashes,not enough to remove H2O2 and O2-production of large numbers of free radicals,eventually restrain the growth.So returning should choose adult tree to cover,rather than a biennial young tree.4.One-year Malus baccata(L.)Borkh.seedlings were planted in the soil from apple orchard after returning branches which aimed to compare the effect of different time and different soil depths on root system behavior.Obvious effect was found in top layer soil both in optimization of root system and in enhancing mitochondrial function,however,the inhibitory effect became more obvious in later stage.Compared with control,Crushing blending treatment slowed the senescence process of seedlings and the decay of mitochondrial function,which consequently helped the root system to absorb soil available nutrients in time.The late growing season,complex Ⅰ,complex Ⅱ,complex Ⅲ,complex IV and alternative oxidase,ATP synthase activity were higher than comparison of 1.14,1.21,1.02,1.28,1.20,and 1.40 times.Potted experiment played a significant effect on root behavior than the experiment in the field.