| Korla fragrant pear is the main cultivated pear variety in Xinjiang.However,due to the drought and less rain in Xinjiang,the soil is barren and the water and moisture conservation is poor.The long-term clean tillage system will lead to the decrease of orchard biomass,the decrease of soil fertility year by year,and the weakening of tree vigor,which seriously affects the quality and yield of fragrant pear.In this study,the differences of soil physical and chemical properties,branches and leaves physical and chemical properties,fruit quality,sugar content and sugar metabolism related enzyme activities in different periods of pear growth and development between clear tillage area and natural grass area were compared.RT-PCR technology was used to determine the expression of sugar metabolism-related enzyme genes in the process of grassing,and the differences in changes were analyzed to provide a scientific basis for improving the fruit quality of Korla fragrant pear:（1）Natural grass cultivation can improve soil physical and chemical properties and increase the content of mineral elements in leaves and branches.Natural grass can increase the content of soil water content, organic matter（31.6%）,alkali-hydrolyzable nitrogen（52.95%）,available phosphorus（23.22%）and total potassium（40.02%）in 0-20cm soil layer of pear orchard,and increase the content of alkali-hydrolyzable nitrogen（52.95%）and total potassium（62.35%）in 20-40cm soil layer.Natural grass can increase soil total potassium content（62.35%）in 40-60cm soil layer and reduce soil p H and electrical conductivity.The total nitrogen,total phosphorus and total potassium of pear branches increased significantly by 23.86%,14.77%and 32.15%after natural grass planting.Total nitrogen,total phosphorus and total potassium in leaves increased significantly by 46.45%,23.38%and 26.67%.The mineral nutrition of pear branches and leaves changed with the change of soil physical and chemical properties,and increased with the increase of soil mineral elements.（2）Natural grass cultivation can improve the comprehensive quality of Korla pear before harvest.Natural grass can increase the single fruit weight（16.97%）,soluble protein（16.11%）,soluble solids（17.36%）, Vc(2.26mg.g-1FW).Natural grass can reduce chlorophyll a（45.72%）,chlorophyll b（34.16%）,carotenoids（59.35%）,total chlorophyll a+b（49.16%）.The content of chlorophyll b in pear flesh decreased by 24.53%.After natural grass,the glucose content of pulp increased by 32.33%,the fructose content increased by 20.46%,and the fructose content was the highest.The fructose content in peel increased by 17.79%.Grass cultivation also significantly increased the activity of hexokinase（HK）and fructokinase（FK）.After natural grass planting,the expression levels of GK,PFK and FK genes were significantly increased by 9.83U/g,4.01U/g and 1.87U/g,and the expression level of PFK gene in peel was significantly increased by 2.52U/g.（3）The storage of natural grass cultivated Korla fragrant pear decreased during postharvest storage.The single fruit weight,transverse diameter,soluble solids,soluble protein,hardness and vitamin C content decreased with the extension of storage,and the longitudinal diameter and fruit shape index basically did not change.At the end of storage,the soluble solids and hardness of Korla Fragrant Pear in natural grass area were significantly reduced by 10.34%and 17.94%,respectively.There was no significant difference in other qualities between the two groups during storage.There was no significant change in the chlorophyll content of the pulp in the grass-growing area.The chlorophyll a and carotenoids in the peel were 20.00%and 85.76%higher than those in the clear tillage area,respectively.The fructose content of the pear pulp was the highest during all storage processes.The glucose and sorbitol contents in the pulp were 23.03%and13.46%higher than those in the clear tillage area.There was no significant difference between the clean tillage area and the grass area during the storage of the peel sugar component.The activity of fructose kinase（FK）was the highest during storage.At the end of storage,the activities of phosphofructokinase（PFK）and hexokinase（HK）in pulp were 19.69U/L and 23.16U/L higher than those in clean tillage area,and the activity of GK in peel was 2.07U/L higher than that in clean tillage area.At the end of storage,there was no significant difference in the expression of genes related to glucose metabolism. |
