| This test in aksu red flag slope orchard,six orchards,ten apple orchard fruit as test materials,selection of high quality and the typical "Fuji" varieties as experimental material,through the weather and soil nutrients in the area,the fruit external quality,internal quality,sugars,sugar metabolism related enzymes,mineral elements were determined,and the produced microstructure in pulp tissue paraffin section observation.The influence of various indexes on the formation of "sugar core" was further analyzed to provide the theoretical basis for cultivation management to improve apple quality and the appearance of "sugar core".As the pillar industry of the fruit industry in aksu region,"sugar core" fruit is also the biggest "selling point" of Fuji apple.It is of great importance to control the appearance of "sugar core" and provide the reference of the optimal picking time for fruit farmers.The research results are as follows:(1)Temperature is one of the main factors in the formation of “Sugar core” in Aksu area.When the daily minimum temperature of the place reaches 0°C and the temperature difference between day and night is greater than 15°C,the sugar in the fruit accumulates during the day and cannot be converted at night.And metabolism,leading to an increase in sugar in the fruit,prone to "sugar core" phenomenon.(2)The occurrence rate of "sugar core" is also closely related to the soil nutrients in the area.According to the results,the soils with high pH value in the soil have low incidence rate of "sugar core",and the area with high organic matter content is beneficial to the appearance of "sugar core".The content of mineral elements N and B is high.The region is also more prone to the phenomenon of "sugar core".(3)Different parts of the harvest time,time," Sugar core " occur rate and fruit external quality,internal quality,sugars,sugar metabolism related enzymes and the content of mineral elements have correlation,test results showed that the red flag,ten orchards Sugar core appeared earlier,began on October 1 and " Sugar core " rate were higher than six.Single fruit weight,fruit hardness and is of certain influence to the formation of " Sugar core ",soluble solids,soluble sugar content in fruit,can promote the formation of the fruit " Sugar core ",in the fruit sugar acid ratio and solid acid ratio is larger,the better the taste and flavor of the fruit.Among them,sucrose and sorbitol content are the most important influencing factors in fruits.With the increase of sucrose and sorbitol content in fruits,when sucrose content reaches 40mg/g and sorbitol content ranges from 9 to 11mg/g,the formation of " Sugar core " in fruits can be accelerated.(4)With the extension of the picking period,AI,NI,SS and SPS in the fruit catalyze the mutual transformation of sucrose,glucose and fructose in the fruit,and SDH can catalyze the formation of sorbitol in the fruit.SPS increased sharply after October 28,when the sucrose in the fruit increased,the enzyme activity in the direction of AI and SS decomposition increased,and a large amount of sucrose was decomposed into glucose and fructose;SDH increased rapidly on October 15 and catalyzed 6-Phosphate sorbitol reacts with NADP+ to form 6-PG and NADPG.The content of each sugar component in the mature fruit is: fructose>sucrose>glucose>sorbitol.The fruit formation "sugar core" is related tothe activity of sucrose-related enzymes,and the most important is the activity of SDH.When the SDH activity reaches the maximum value,the "sugar core" in the fruit begins to form in large quantities.(5)Paraffin section observation showed that the cells of "sugar core" and "non-sugar core" were intact,but there were significant differences in cell size and gap between the two.After staining with xylene,the cell wall of the cell presents a complete outline.The cell of the "sugar core" is dense and has many black substances.Considering that when the fruit reaches maturity,the sorbitol in the fruit is continuously transmitted to the inside of the fruit through the vascular bundle.Due to the large temperature difference between day and night in the Aksu area,the sorbitol accumulated during the day cannot be metabolized and transformed in time,accumulating in the intercellular space,making the cell wall transparent,leading to the appearance of "sugar cores" in the fruit,mostly around the vascular bundle. |
