A planting method that can effectively reduce the browning of the flesh of southern Hunan oil nai

Abstract

The invention discloses a planting method that can effectively reduce the browning of Hunan oil nai pulp, comprising the following steps: a. In summer, April-May, twist the long branches of the tree body; b. Delay bagging, bagging after the second physiological fruit drop and the late stage of fruit expansion; c. After harvesting the fruit in July-August, pull the long branches to ensure that there are no upright long branches in the crown; d. Reduce the amount of nitrogen fertilizer used in autumn basal fertilizer, increase the amount of organic fertilizer used, and supplement the trace element fertilizers such as boron, zinc, calcium, and magnesium; e. From the young fruit stage to the late stage of expansion, spray the leaves with liquid sugar alcohol calcium fertilizer 4 to 5 times, and each spraying interval is 10 to 15 days. The method of the present invention can effectively reduce the browning of Hunan oil nai pulp, is simple to operate, and is easy to promote.

Description

Technical Field

[0001] The invention relates to a fruit planting method, in particular to a planting method capable of effectively reducing the browning of Xiangnan oil nai fruit pulp. Background Art

[0002] Nai Li is a cultivated variety of Chinese plum with a long history of cultivation. It is widely planted in southern Hunan. At present, the main variety planted is the yellow-fleshed oil nai, which uses mature fruit bagging technology. Generally, it is bagged when the fruit drops for the second time in early May. The fruit surface is golden in color, matures early, and is sold at a higher price, which can achieve better economic benefits.

[0003] Since 2019, with the extremely high temperatures in June and July, the flesh of the nai plums planted in southern Hunan has become soft, the tissue has become spongy, and the area near the core has turned brown after bagging at maturity, which has made them lose their commercial value and caused huge losses. In 2020, the browning rate of nai plums in Rucheng County was found to be over 80%, and 20% of the orchards had browning flesh throughout the orchard, causing serious economic losses.

[0004] There is no mature scientific research report on the cause of browning of the flesh of naan during its growth period. In recent years, fruit farmers and researchers have tried to reduce the browning of naan by spraying calcium fertilizer on the leaves, but the effect is not obvious.

[0005] Browning of the flesh of naan is a physiological disease. High temperature is the main external cause of browning of the flesh of naan during its growth period. The effect of controlling the browning of the flesh of naan by a single measure is not obvious. Therefore, it is necessary to develop a planting method that can effectively reduce the browning of the flesh of naan in southern Hunan to reduce the browning rate of the flesh of naan. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a planting method which can effectively reduce the browning of the flesh of southern Hunan oil nai, so as to effectively reduce the browning rate of the flesh of oil nai.

[0007] In order to solve the above technical problems, the planting method of the present invention which can effectively reduce the browning of Xiangnan oil nai pulp comprises the following steps:

[0008] a. In summer, from April to May, twist the tree's overgrown branches;

[0009] b. Delayed bagging: bagging after the second physiological fruit drop and in the late stage of fruit expansion;

[0010] c. After harvesting the fruits in July and August, pull the overgrown branches to ensure that there are no upright overgrown branches in the crown;

[0011] d. Reduce the amount of nitrogen fertilizer used in autumn basal fertilizer, increase the amount of organic fertilizer used, and add fertilizers containing trace elements such as boron, zinc, calcium, and magnesium;

[0012] e. From the young fruit stage to the late fruit expansion stage, spray liquid sugar alcohol calcium fertilizer on the leaves 4 to 5 times, with an interval of 10 to 15 days between each spraying.

[0013] In the step d, 12 parts by weight of urea, 11 parts of monoammonium phosphate, and 65 parts of potassium nitrate are used to prepare a low-nitrogen, high-potassium compound fertilizer with N﹕P﹕K=15﹕7﹕30, and 0.5 to 1 kg is applied to each tree; 50 kg to 100 kg of organic fertilizer is applied to each tree; 400 g of boron, zinc, and other trace element fertilizers are supplemented to each tree, and 2 to 3 kg of calcium magnesium phosphate fertilizer is supplemented; the N of urea is ≥46%; the N﹕P﹕K of monoammonium phosphate is 12﹕61﹕0; the N﹕P﹕K of potassium nitrate is 13.5﹕0﹕46.

[0014] In the step e, the calcium content in the liquid sugar alcohol calcium fertilizer is ≥18%, and the sugar alcohol content is ≥11%. When spraying on the leaves, it is diluted 1500 to 2000 times and sprayed evenly.

[0015] When raising seedlings, use Zhongtao Kangzhi No. 1 as the rootstock for grafting.

[0016] The orchard adopts a grass cultivation mode between the rows. Purple-flowered glossy-leaved vetch is sown in October with a sowing density of 1.5kg / mu. After the purple-flowered glossy-leaved vetch dies naturally the following year, sweet potato seedlings are planted between the rows in May of the following year with a planting spacing of 50cm×50cm.

[0017] Before flowering and during the fruit expansion period, water-soluble fertilizer is irrigated externally on the roots. The water-soluble fertilizer is made by mixing 60 parts by weight of seaweed extract, 10 parts by weight of humic acid, 35 parts by weight of amino acids, 64 parts by weight of potassium fulvic acid, 1 part by weight of trace elements, and 10 parts by weight of water. The roots are irrigated externally 2 to 3 times using a fertilizer gun or drip irrigation. The potassium fulvic acid contains 52 parts by weight of fulvic acid and 12 parts by weight of potassium oxide.

[0018] Set up a mist device in the orchard and spray in the early morning or evening, with each spraying lasting 1 to 2 hours.

[0019] In late June, when the temperature in the orchard is higher than 32℃, the tree crowns are covered with black 6-needle shade nets. Three days before harvest, the shade nets are removed from the tree crowns.

[0020] About 7 days before the fruit matures, spray exogenous melatonin and ascorbic acid on the leaves once; the purity of exogenous melatonin is more than 98%, first dissolved in anhydrous ethanol and then prepared with water, and the spraying concentration is 1mmoL / L; the purity of ascorbic acid is more than 99%, directly dissolved in water, and the spraying concentration is 4mmoL / L.

[0021] In the above step b, the fruit bags are white single-layer light-transmitting bags or yellow outer and white inner single-layer light-shielding fruit bags.

[0022] The method of the present invention adopts the technical means of delaying bagging, twisting and pulling the long branches, reducing the use of nitrogen fertilizer, increasing the use of organic fertilizer, spraying liquid sugar alcohol calcium fertilizer on the leaves from the young fruit stage to the late expansion stage, etc., so as to avoid the temperature in the fruit bag being too high in the high temperature season of May and early June, reduce the transpiration of the tree body in the high temperature weather in summer, enhance the tree vigor, balance the nutrition to improve the sugar content and quality of the fruit, supplement the nutrition on the leaves to increase the calcium content in the fruit to improve the resistance of the fruit to high temperature, thereby effectively reducing the browning rate of the flesh and overcoming the defects of the prior art.

[0023] The method of the invention is simple to operate, stable and reliable, and is easy to promote and use.

[0024] The above technical solution is the result of long-term research and experiment by the applicant's scientific research team. The experiment site is Erdu Village, Wenming Yao Ethnic Township, Rucheng.

[0025] Delaying the bagging time, bagging after the second physiological fruit drop and in the late stage of fruit expansion, can avoid the high temperature season in May and early June, prevent the temperature in the fruit bag from being too high, and effectively reduce the browning rate of the flesh.

[0026] Previously, most fruit farmers started bagging in early May and finished bagging in early June. Because bagging was too early, some fruits fell, wasting unnecessary labor and money. In addition, bagging too early could easily lead to excessively high temperatures in the fruit bags, causing the flesh to brown. When bagging in May, the highest temperature in the fruit bags can reach 43.1°C, the average temperature is as high as 29.9°C, the fruit bagging rate can reach 11%, and the flesh browning rate can reach 16%. Postponing bagging until June can reduce the average temperature in the fruit bags by 2.4°C, the fruit bagging rate can be reduced by 8%, and the fruit browning rate can be reduced by 5%. See Table 1.

[0027]

[0028] For further improvement, white single-layer light-transmitting bags or yellow outer and white inner single-layer light-shielding fruit bags can be used, which can not only lower the temperature inside the fruit bags, but also reduce the infection of pests and diseases and increase the commercial quality of the fruit.

[0029] In Wenming Yao Ethnic Township, Rucheng County, a test of bagging different fruit bags was conducted. The results are shown in Table 2. The single fruit weight and soluble solids of the unbagged fruit were higher than those of the bagged experimental group. The soluble solids content of the experimental group with white fruit bags was higher than that of the double-layer shading bag. The solid-acid ratio of the unbagged and white fruit bags was significantly higher than that of the double-layer bagged experimental group. We can also see that after the double-layer shading bag was used, the proportion of fruit browning was seriously aggravated. The browning rate of the flesh of the unbagged fruit increased significantly from 6% to more than 16% in the shading bag.

[0030] The browning rate of unbagged nai plum flesh is significantly lower than that of bagged ones. The reason is that the temperature inside the fruit bag increases after bagging. High temperature will cause a sharp increase in the browning rate of nai plum flesh, and the impact of double-layer bags is higher than that of single-layer bags, and single-layer bags are higher than unbagged ones. If the fruit is not bagged, the fruit is not blocked from the sun, and more photosynthesis products accumulate, which will significantly increase the quality of the fruit, improve the sugar content and flavor, and reduce the browning rate. However, in order to ensure the cleanliness and color of oil nai fruit, the industry still requires bagging. Therefore, the applicant proposed a technical solution for delayed bagging.

[0031]

[0032] In summer, from April to May, the tree's leggy branches are twisted to ensure that there are no upright leggy branches in the crown. This can not only reduce the tree's transpiration in high temperature weather in summer and reduce the browning rate of fruit, but also promote the differentiation of flower buds on the leggy branches and transform them into fruiting branches, which is beneficial to increase the tree's light transmittance, make the flower buds plump, increase the fruit sugar content, increase the fruit yield in the following year, and reduce the amount of winter pruning, avoid the waste of tree nutrients, and save labor costs.

[0033] After harvesting the fruits at the end of July and the beginning of August, the long branches in the crown are pulled to ensure the normal differentiation of flower buds on the upright branches, reduce the amount of pruning in winter, avoid excessive thinning of long upright branches in winter, waste a lot of tree nutrients, and avoid a large number of upright branches emerging from the cuts the following year, wasting nutrients in the second year. The reduction of long branches in summer can avoid the transpiration of high temperature on the fruits of Nai Li, and reduce the sponginess and browning rate of fruit tissue. See Table 3.

[0034]

[0035] In autumn, the amount of nitrogen fertilizer used is reduced, the amount of organic fertilizer used is increased, and medium and trace element fertilizers such as boron, zinc, calcium, and magnesium are supplemented. A low-nitrogen and high-potassium compound fertilizer with a N:P:K=15:7:30 ratio is prepared by weight of 12 parts of urea, 11 parts of monoammonium phosphate, and 65 parts of potassium nitrate. 0.5 to 1 kg is applied to each tree; 50 to 100 kg of organic fertilizer is applied to each tree; 400 g of medium and trace element fertilizers such as boron, zinc, and 2 to 3 kg of calcium, magnesium, and phosphate fertilizers are supplemented to each tree. This can reduce the amount of nitrogen fertilizer used, enhance tree vigor, balance nutrition, improve fruit sugar content and quality, and further reduce the browning rate of fruit.

[0036] In late September and early October in autumn, dig a 30cm deep trench at the drip line of the tree canopy and apply basal fertilizer in the trench. The basal fertilizer is mainly organic fertilizer. Apply 25kg of commercial organic fertilizer or 50kg of organic fertilizer from farmyard compost per plant, 1kg of low-nitrogen and high-potassium compound fertilizer, 100g of medium and trace element fertilizers such as boron and zinc per plant, and 5kg of calcium, magnesium and phosphate fertilizer per plant, which can significantly reduce the browning rate of Nai Li fruit in the following year. See Table 4.

[0037]

[0038] From the young fruit stage to the late expansion stage, spray liquid sugar alcohol calcium fertilizer on the leaves 4 to 5 times, with an interval of 10 to 15 days between each spraying. The calcium content in the liquid sugar alcohol calcium fertilizer is ≥18%, and the sugar alcohol is ≥11%. When spraying on the leaves, dilute it 1500 to 2000 times and spray it evenly. It can supplement nutrients through the leaves, increase the calcium content in the fruit, improve the fruit's resistance to high temperatures, and further reduce the browning rate of the flesh. The applicant's team conducted a preliminary experiment on spraying sugar alcohol calcium from young fruits to the late expansion stage of Naili, and designed intervals of 30d, 15d, and 10d. It was found that an interval of 1 month can slightly reduce the browning rate of the flesh, but the effect is not as significant as the intervals of 10d and 15d. There is not much difference in the effect of spraying sugar alcohol calcium with an interval of 10d and an interval of 15d, but an interval of 10d will lead to an increase in labor and increase production costs. The applicant recommends that the interval between spraying sugar alcohol calcium is 10 to 15 days, and some low-altitude production areas will start harvesting fruits in mid-to-late July, so the number of spraying sugar alcohol calcium is 4-5 times.

[0039] Spraying 1500 times of calcium glycoside liquid on the leaves 4 to 5 times during the fruit young stage to the late stage of fruit expansion from May to July can significantly increase the fruit hardness, increase the fruit weight, improve the fruit quality, and reduce the fruit browning rate. See Table 5.

[0040]

[0041] As a further improvement, when raising seedlings, use Zhongtao Kangzhen No. 1 as the rootstock for grafting and raising seedlings. The rootstock is pure, pest-free, and fully mature Zhongtao Kangzhen No. 1 seeds for sand storage and cultivation. Since Zhongtao Kangzhen No. 1 has good drought resistance, it is beneficial to improve the resistance of the tree, increase the tree's resistance to high temperature, drought and disease, and help further reduce the browning rate of the flesh.

[0042] Ordinary peach and Anti-root No. 1 were selected to graft golden plum, and the growth and resistance of the grafted seedlings were observed. The results showed that the use of medium peach Anti-root No. 1 to graft plum had good affinity, smooth grafting joints, vigorous tree vigor, fast growth, and could significantly increase the trunk thickness and yield, and reduce the browning rate of plum flesh. See Table 6.

[0043] Table 6 Comparison of different rootstocks grafted with golden plum

[0044]

[0045] As a further improvement, the orchard adopts a grass cultivation mode between rows, sowing purple-flowered glossy-leaved vetch in October, with a sowing density of 1.5kg / mu; wait for the purple-flowered glossy-leaved vetch to die naturally the following year, and plant sweet potato seedlings between rows in May of the following year, with a planting spacing of 50cm×50cm. In this way, the orchard surface coverage can be increased, the soil temperature can be reduced, the soil moisture and nutrients can be maintained, and the adaptability of the root system of the nai plum to the high temperature in summer can be enhanced, which is conducive to further reducing the browning rate of the flesh.

[0046] After interplanting sweet potato leaves and purple-flowered glossy vetch between the rows of the nai plum garden, the number of weeds and the surface temperature can be significantly reduced, the surface soil moisture can be increased, the soil pH can be adjusted, the content of soil organic matter, nitrogen, phosphorus, potassium, calcium and magnesium can be increased, and the yield of nai plum can be increased. See Table 7 and Table 8.

[0047]

[0048]

[0049] As a further improvement, before flowering and during the fruit expansion period, water-soluble fertilizer is irrigated outside the roots. The water-soluble fertilizer is made by mixing 60 parts by weight of seaweed extract, 10 parts of humic acid, 35 parts of amino acids, 64 parts of potassium fulvic acid, 1 part of trace elements, and 10 parts of water. The fertilizer gun or drip irrigation is used for 2 to 3 times of irrigating outside the roots. The potassium fulvic acid contains 52 parts by weight of fulvic acid and 12 parts of potassium oxide. This is beneficial to increase the vitality of the root system, increase the number of beneficial microorganisms in the soil, improve the resistance of the tree, and reduce the browning rate of the fruit.

[0050] As a further improvement, a misting device is set up in the orchard to spray in the early morning or evening, with each spraying time of 1 to 2 hours. This is beneficial to lower the overall temperature of the orchard and avoid excessive temperature inducing browning of the fruit flesh.

[0051] As a further improvement, in late June, when the temperature in the orchard is higher than 32°C, the tree crown is covered with a black 6-pin sunshade net, and the sunshade net is removed from the tree crown 3 days before harvest. This is beneficial to lower the temperature in the tree crown and fruit bag, and reduce the browning rate of the fruit. At the same time, removing it before harvest can avoid the reduction of fruit sugar content due to too long shading time.

[0052] In June 2021, a tree crown covering shade net experiment was carried out at the Duohao Fruit and Vegetable Cooperative Demonstration Base in Wenming Yao Ethnic Township. The tree crown was covered with 8-meter-wide 6-needle new material shade net. On July 28, 30 fruits were collected from the top and the inner part of the fruit tree for analysis. The results showed that after covering the shade net, the browning rate of the top fruit of the plum tree was reduced by 36.11%, and the browning rate of the inner fruit was reduced by 30.56%. Covering the shade net can significantly reduce the browning of plum fruit. See Table 9.

[0053]

[0054] As a further improvement, about 7 days before the fruit matures, spray exogenous melatonin and ascorbic acid on the leaves once; the purity of exogenous melatonin is more than 98%, first dissolved in anhydrous ethanol, then prepared with water, and the spraying concentration is 1mmoL / L; the purity of ascorbic acid is more than 99%, directly dissolved in water, and the spraying concentration is 4mmoL / L. This is beneficial to delay the aging of tree leaves and fruits, induce the activity of active oxygen scavenging enzymes in the fruit, avoid aging caused by oxidative damage to the fruit, and then reduce the browning rate of the fruit. DETAILED DESCRIPTION

[0055] The method of the present invention is described in detail below.

[0056] The planting method of the present invention, which can effectively reduce the browning of Xiangnan oil nai fruit pulp, adopts the following technical means:

[0057] When raising seedlings, use Zhongtao Kangzhen No. 1 as the rootstock for grafting and raising seedlings. The rootstock is pure, disease-free, and fully mature Zhongtao Kangzhen No. 1 seeds for sand storage and cultivation.

[0058] In summer, from April to May, the tree's overgrown branches are twisted.

[0059] Before flowering and during the fruit expansion period, water-soluble fertilizer is applied externally to the roots. The water-soluble fertilizer is made by mixing 60 parts by weight of seaweed extract, 10 parts of humic acid, 35 parts of amino acids, 64 parts of potassium fulvic acid, 1 part of trace elements, and 10 parts of water. The fertilizer gun or drip irrigation is used for external irrigation 2 to 3 times. Potassium fulvic acid contains 52 parts by weight of fulvic acid and 12 parts of potassium oxide.

[0060] Delaying the bagging time, bagging after the second physiological fruit drop and in the late stage of fruit expansion, can avoid the high temperature season in May and early June and postpone bagging to after June.

[0061] You can choose to use white single-layer light-transmitting bags or single-layer light-shielding fruit bags with yellow outside and white inside. These can not only lower the temperature inside the fruit bags, but also reduce the infection of pests and diseases and increase the marketability of the fruit.

[0062] From the young fruit stage to the late stage of fruit expansion, spray liquid sugar alcohol calcium fertilizer on the leaves 4 to 5 times, with an interval of 10 to 15 days between each spraying. The calcium content in the liquid sugar alcohol calcium fertilizer should be ≥18%, and the sugar alcohol should be ≥11%. When spraying on the leaves, dilute it 1500 to 2000 times and spray evenly.

[0063] Set up a misting device in the orchard and spray it in the early morning or evening for 1 to 2 hours each time. This will help lower the overall temperature of the orchard and prevent excessive temperature from inducing browning of the flesh.

[0064] In late June, when the temperature in the orchard is higher than 32℃, the tree crowns are covered with black 6-needle shade nets. Three days before harvest, the shade nets are removed from the tree crowns.

[0065] About 7 days before the fruit matures, spray exogenous melatonin and ascorbic acid on the leaves once; the purity of exogenous melatonin is more than 98%, first dissolved in anhydrous ethanol and then prepared with water, and the spraying concentration is 1mmoL / L; the purity of ascorbic acid is more than 99%, directly dissolved in water, and the spraying concentration is 4mmoL / L.

[0066] After harvesting the fruits in July and August, pull the overgrown branches on the tree to ensure that there are no upright overgrown branches in the crown.

[0067] In autumn, reduce the amount of nitrogen fertilizer used as base fertilizer, increase the amount of organic fertilizer used, supplement with boron, zinc, calcium, magnesium and other trace element fertilizers, use 12 parts of urea (N≥46%), 11 parts of monoammonium phosphate (N﹕P﹕K=12﹕61﹕0), 65 parts of potassium nitrate (N﹕P﹕K=13.5﹕0﹕46) to prepare a low-nitrogen and high-potassium compound fertilizer with N﹕P﹕K=15﹕7﹕30, apply 0.5 to 1kg per tree; apply 50kg to 100kg of organic fertilizer per tree; supplement each tree with 400g of boron, zinc and other trace element fertilizers, and 2 to 3kg of calcium, magnesium and phosphate fertilizers.

[0068] In late September and early October in autumn, dig a 30cm deep trench at the drip line of the tree crown, apply base fertilizer in the trench, apply 25kg of commercial organic fertilizer or 50kg of organic fertilizer fermented in farm compost per plant, apply 1kg of low-nitrogen and high-potassium compound fertilizer, 100g of boron, zinc and other trace element fertilizers and 5kg of calcium, magnesium and phosphate fertilizer per plant.

[0069] The orchard adopts a grass cultivation mode between the rows. Purple-flowered glossy-leaved vetch is sown in October with a sowing density of 1.5kg / mu. After the purple-flowered glossy-leaved vetch dies naturally the following year, sweet potato seedlings are planted between the rows in May of the following year with a planting spacing of 50cm×50cm.

Claims

1. A planting method that can effectively reduce the browning of Xiangnan oil nai pulp, characterized in that The steps include: a. In summer, from April to May, twist the tree's overgrown branches; b. Delayed bagging: bagging after the second physiological fruit drop and in the late stage of fruit expansion; c. After harvesting the fruits in July and August, pull the overgrown branches to ensure that there are no upright overgrown branches in the crown; d. Reduce the amount of nitrogen fertilizer used in autumn basal fertilizer, increase the amount of organic fertilizer used, and add trace element fertilizers such as boron, zinc, calcium, and magnesium; e. From the young fruit stage to the late stage of fruit expansion, spray the leaves with liquid sugar alcohol calcium fertilizer 4 to 5 times, with an interval of 10 to 15 days between each spraying; In the step d, 12 parts by weight of urea, 11 parts of monoammonium phosphate, and 65 parts of potassium nitrate are used to prepare a low-nitrogen, high-potassium compound fertilizer with N﹕P﹕K=15﹕7﹕30, and 0.5 to 1 kg is applied to each tree; 50 kg to 100 kg of organic fertilizer is applied to each tree; 400 g of boron and zinc trace element fertilizers and 2 to 3 kg of calcium magnesium phosphate fertilizer are supplemented to each tree; the N of urea is ≥46%; the N﹕P﹕K of monoammonium phosphate is 12﹕61﹕0; and the N﹕P﹕K of potassium nitrate is 13.5﹕0﹕46.

2. The method according to claim 1, characterized in that: In the step e, the calcium content in the liquid sugar alcohol calcium fertilizer is ≥18%, and the sugar alcohol content is ≥11%. When spraying on the leaves, it is diluted 1500 to 2000 times and sprayed evenly.

3. The method according to claim 1, characterized in that: When raising seedlings, use Zhongtao Kangzhi No. 1 as the rootstock for grafting.

4. The method according to claim 1, characterized in that: The orchard adopts a grass cultivation mode between the rows. Purple-flowered glossy-leaved vetch is sown in October with a sowing density of 1.5kg / mu. After the purple-flowered glossy-leaved vetch dies naturally the following year, sweet potato seedlings are planted between the rows in May of the following year with a planting spacing of 50cm×50cm.

5. The method according to claim 1, characterized in that: Before flowering and during the fruit expansion period, water-soluble fertilizer is irrigated externally on the roots. The water-soluble fertilizer is made by mixing 60 parts by weight of seaweed extract, 10 parts by weight of humic acid, 35 parts by weight of amino acids, 64 parts by weight of potassium fulvic acid, 1 part by weight of trace elements, and 10 parts by weight of water. The roots are irrigated externally 2 to 3 times using a fertilizer gun or drip irrigation. The potassium fulvic acid contains 52 parts by weight of fulvic acid and 12 parts by weight of potassium oxide.

6. The method according to claim 1, characterized in that: Set up a mist device in the orchard and spray in the early morning or evening, with each spraying lasting 1 to 2 hours.

7. The method according to claim 1, characterized in that: In late June, when the temperature in the orchard is higher than 32℃, the tree crowns are covered with black 6-needle shade nets. Three days before harvest, the shade nets are removed from the tree crowns.

8. The method according to claim 1, characterized in that: About 7 days before the fruit matures, spray exogenous melatonin and ascorbic acid on the leaves once; the purity of exogenous melatonin is more than 98%, first dissolved in anhydrous ethanol and then prepared with water, and the spraying concentration is 1mmoL / L; the purity of ascorbic acid is more than 99%, directly dissolved in water, and the spraying concentration is 4mmoL / L.

9. The method according to claim 1, characterized in that: In the above step b, the fruit bags are white single-layer light-transmitting bags or yellow outer and white inner single-layer light-shielding fruit bags.

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