Abstract:【Objective】Pear is a billion dollar characteristic forest fruit industry in southern Xinjiang，and Korla fragrant pear is the main cultivated variety. In recent years，the main trunk dense planting pear orchard has developed rapidly and entered the peak fruiting period. With the increase of tree age，problems such as weak tree resistance，easy death，and unstable yield have become prominent in dense planting pear orchards.Fertilization methods affect the distribution of fruit tree roots and nutrient utilization，and are closely related to tree resistance and yield. Fertilization in mature and densely planted pear orchards is often carried out at the edge of the tree crown，about 1 meter away from the main trunk，by opening a strip-shaped ditch for fertilization. As the tree ages，further research is needed to determine whether this fertilization method is reasonable under dense planting conditions. Study the spatial characteristics of root system and soil physicochemical properties of densely planted mature Korla pears under long-term strip fertilization，providing a basis for scientific and efficient water and fertilizer management in densely planted pear orchards. 【Methods】Using profile excavation method and WinRHIZO root analysis system，the root morphology of 11 year old pear orchard was analyzed at a distance of 50-200 cm between rows and tree trunks，and at a depth of 10-110 cm. Soil organic matter，available nutrients，soil bulk density，porosity，saturated water content，field water holding capacity and other soil physical and chemical properties were measured. 【Results】 The results showed that the length and surface area of pear roots were mainly dominated by absorbing roots，accounting for 92.57% and 62.62%，respectively; The root volume is mainly transported by roots，accounting for 52.98%. In the horizontal direction，the root length and root surface area density are highest near the fertilization ditch，accounting for 32.32% and 27.06% respectively; The proportion of root length and root surface area in the soil layer at a depth of 30-50 cm in the vertical direction is the highest，accounting for 26.33% and 25.99%，respectively. The average root length density in the area with a depth of 10-90 cm and a horizontal distance of 140 cm is 0.62 mm/cm3，accounting for 75.56% of the total root length in the sampling area. It is a densely distributed area of pear root system. There are differences in the enrichment areas of different nutrients in long-term strip fertilization. Organic matter and available phosphorus accumulate at a distance of 1 meter from the main stem in the fertilization ditch，and exhibit layered distribution characteristics. The content of organic matter and available phosphorus in deep soil is extremely low，with soil organic matter and available phosphorus content at a depth of 10-30 cm being 2.62 times and 16.28 times higher than that at a depth of 90-110 cm，respectively; The distribution of alkaline nitrogen and available potassium from the fertilization ditch towards the main stem direction is significantly higher than that towards the inter row direction. The content of alkaline nitrogen and available potassium in the soil at 50-80 cm is 1.35 times and 1.21 times higher than that at 140-170 cm，respectively; Alkaline hydrolyzable nitrogen and available potassium accumulate in deep soil layers，with the alkaline hydrolyzable nitrogen content at depths of 90-110 cm being 2.28 times higher than that at depths of 10-30 cm. There is a significant difference in the physical properties of soil between fertilization ditches and rows at a depth of 10-50 cm. Compared with the fertilization ditches，the soil bulk density significantly increases at the main stem 150 cm away from rows that are subjected to mechanical compaction for a long time，while porosity，saturated water holding capacity，and field water holding capacity decrease. The nutrient content of roots and soil is closely related to spatial location. The correlation coefficients between V and VI grade roots and soil depth are 0.45 and 0.62，respectively，showing a significant positive correlation and extremely significant positive correlation. The correlation coefficients between I and IV grade roots and horizontal distance are -0.55 and -0.45，respectively，showing a significant negative correlation; The correlation coefficients between organic matter and available phosphorus and soil depth are -0.73 and -0.74，respectively，showing a highly significant negative correlation. The correlation coefficient between alkaline nitrogen and soil depth is 0.55，showing a significant positive correlation. The correlation coefficient between available potassium content and horizontal distance is -0.66，showing a highly significant negative correlation. There is a highly significant positive correlation between grade I-II root systems and available phosphorus，with correlation coefficients of 0.70 and 0.64，respectively.【Conclusion】In summary，under long-term strip fertilization，organic matter and phosphorus nutrients in densely planted pear orchards accumulate in and near the fertilization ditch，and the soil porosity and water holding capacity at the inter row mechanical compaction site decrease. The spatial differences in the distribution of organic matter and available nutrients，as well as the differences in soil physical properties between the fertilization ditch and mechanical compaction site，are unfavorable factors for the root extension and growth of mature densely planted Korla fragrant pear orchards.
PDF （）