Study On The Mechanism Of Continuous Cropping Obstacle Of Passion Fruit In Guizho

Passiflora edulis is native to North America and is a plant of the genus P.edulis in the Passifloraceae family,which has a large socio-economic value in terms of food and medicinal uses.With the increasing demand for P.edulis in the market,the planting situation of P.edulis producing areas has occurred frequently year after year.It was found that successive cultivation of P.edulis in the same plot would result in successive crop barriers,such as the decline of yield and quality,the change of soil microbial community structure,the decline of soil site quality,etc,however,at present,the occurrence law and regulation mechanism of P.edulis continuous cropping obstacle are not clear.In this paper,field sampling and control experiments were used to study the soil physical and chemical properties,enzyme activity,microbial community structure and the effects on the growth,yield and quality of P.edulis after continuous cropping for 0 ～ 5 years(represented by T0,T2,T3,T4 and T5).At the same time,the effects of different organ extracts and soil extracts of P.edulis on Seed Germination and seedling growth were studied.To explore the reasons for the obstacle of P.edulis continuous cropping and analyze its formation mechanism,so as to provide technical support for the healthy development of P.edulis industry in Guizhou.The main results are as follows:(1)After continuous cropping of P.edulis,its plant growth and development were slow,the yield and quality decreased significantly,and there were obvious continuous cropping obstacles.(2)Crop succession decreases soil capillary porosity and total porosity and increases soil bulk,indicating that crop succession increases soil cohesiveness and that soil p H increases year by year and gradually tends to be neutral,but gradually deviates from the suitable p H range for P.edulis cultivation.Soil fast-acting phosphorus,alkaline nitrogen,total nitrogen,total phosphorus and organic matter all show a trend of increasing and then decreasing,reaching a maximum at T3,while fast-acting potassium shows a yearly increase.It shows that continuous cultivation of P.edulis has a significant impact on the physical and chemical properties of the soil,resulting in soil consolidation,deviation of soil p H from the suitable zone for P.edulis cultivation and nutrient imbalance,which affects the yield and quality of P.edulis.(3)Continuous cropping caused different degrees of changes in peroxidase activity,acid phosphatase activity,sucrase activity and urease activity in inter-root soils of P.edulis.The change of enzyme activity in rhizosphere soil affected the absorption of different nutrient elements by P.edulis,induced continuous cropping obstacles,and decreased the yield and quality of P.edulis.(4)Based on the analysis of high-throughput sequencing results,it was found that continuous crop has altered the abundance and diversity of soil microorganisms in the interrhizosphere of P.edulis,with a significant increase in the abundance of pathogenic genera such as Mortierella,Fusarium and Bacillus,and significant differences between microbial community structure groups,resulting in an ecological imbalance of inter-rhizosphere microorganisms.(5)The continuous cultivation of P.edulis succession leads to a decline in soil stand quality,and there is a linear relationship between the yield of P.edulis and stand quality,with the better the stand quality the higher the yield.Total nitrogen content,alkaline nitrogen content,fastacting phosphorus content,abundance of the genus Arthrobacter,bulk density,peroxidase activity,abundance of the genus Fusarium,abundance of the genus Bacillus,total potassium content,abundance of the genus norank＿f＿＿norank＿o＿＿Subgroup＿2 and abundance of the genus Slantcap mushroom had a greater effect on yield.Bulk density,total nitrogen content,total potassium content,Fusarium abundance and Bacillus abundance were the five soil factors that had the greatest impact on the yield of P.edulis.(6)The continuous crop of P.edulis has a strong chemosensitive autotoxic effect,and its seed germination,germination index,seedling height and biomass are all inhibited to some extent by different organs and inter-root soil extracts.The inhibitory effect was gradually increased with increasing concentration of the extract.The effects of different organs and interroot soil extracts on the germination of P.edulis seeds and seedling growth were different,and the chemosensory inhibition of seed germination was ranked as leaf > fruit > inter-root soil >stem.The chemosensory inhibition of seedling growth by infusions from different organs and inter-root soil of P.edulis was ranked as stem>leaf>inter-root soil>fruit...