What are the measures for increasing yield and improving quality in greenhouse peach cultivation

Greenhouse peach cultivation has developed rapidly in recent years because it ripens the fruit early, fills the off-season gap in the fruit market, and commands higher prices. However, it also suffers from low fruit set rates, low yields, and declining quality, which urgently need to be solved. Through continuous exploration in production, we have summarized the following management measures for everyone's reference.

1. Selecting superior varieties: The quality of the variety and whether the selection is correct directly determines the success or failure of greenhouse peach cultivation, so high-quality peach trees should be selected for the greenhouse to avoid unnecessary losses. Through observation and evaluation in recent years, the following varieties are preliminarily proposed for protected cultivation. 1. Nectarine varieties include: Ruiguang No. 1, 3, 5, Zaohongzhu, Hongbaoshi, Shuguang, Huaguang, Yanguang, Wuyuehuo, Zaomeiguang, Zaohongxia, Danmo, Zaohong No. 2 and other sweet nectarine varieties; 2. Common peach varieties include: Annong Shuimi, Zaoxialu, Yuhualu, Qingfeng, Jingchun, Beijing No. 2, Xiahui No. 1, Chunfeng, Chunyan, Chunhua, Bumu Zaosheng, Shazi Zaosheng, etc.; 3. Flat peach varieties include: Zaolu Pantao, Xinhong Zao Pantao, Zaohuang Pantao, etc., all of which are ideal varieties for protected cultivation. Their common characteristics are weak trunk habit, fast growth, easy flower formation, early maturity, large fruit, beautiful shape and color, excellent quality, and tolerance to storage and transport.

When selecting varieties, one should also consider that the chilling requirement should be low, choose varieties with abundant pollen and high self-pollination fruit set rates as much as possible, and pay attention to configuring 2-3 pollinator varieties with similar flowering periods.

2. Temperature management:

Only by managing temperature well can flower quality be ensured and fruit set and fruit development be promoted. Raising the temperature must only be carried out after the peach tree's chilling requirement has been met.

1. From the start of warming to before flowering. During this period, the warming rate should be slow and the temperature should not be too high, otherwise budding will be uneven. During the day, 18-20°C is appropriate; at night, 5-7°C, and it must not go below 5°C.

2. Flowering period. At night it must not go below 6°C; during the day it should be above 15°C, with a maximum not exceeding 25°C. Too low a temperature will affect pollen tube growth. On cloudy and rainy days or during low temperatures, attention should be paid to heating. At this time, attention should also be paid to the air humidity in the greenhouse, with 50%-60% being appropriate. When insufficient, water should be sprayed on the soil to increase humidity; if humidity is too low, the stigma becomes too dry and pollen tubes cannot germinate; if too high, ventilation should be used to reduce humidity.

3. Fruit enlargement period. During this period, the temperature should be high. At low temperatures, fruit enlargement is poor and there are many small fruits. Therefore, the night temperature should not be below 12°C, and during the day it should be 25-27°C. In the late fruit enlargement period, during the day it should be 28°C, and at night 15-17°C.

3. Fertilizer and water management:

Base fertilizer can be applied after leaf fall in autumn at an amount of high-quality, well-decomposed barnyard manure per mu. Topdressing is generally done 3 times per year, respectively before flowering, during the pit-hardening stage, and during the fruit coloring stage. During the growing period, combined with pest and disease control, foliar fertilizer can be sprayed: 0.3% urea 2-3 times, and 500 times monopotassium phosphate 2 times.

Watering can be done after each topdressing, and overwintering water should be applied before the soil freezes. Small amounts of water should be applied frequently, that is, the amount of water each time should not be too large, while the frequency can be appropriately increased. During the fruit coloring stage, irrigation must be controlled to prevent fruit cracking, and soil moisture content should be controlled at 50%-60%. Watering time should be chosen on sunny mornings, when the water temperature is close to the soil temperature and will not cause a large temperature drop.

4. Fine flower and fruit management:

1. Flower thinning. It is best done at the bud stage, and should be light thinning, only removing overly dense small flowers and small buds; 2. Pollination. There are no insects in the greenhouse and no ventilation, so artificial pollination or placing bees in the greenhouse must be done to ensure the fruit set rate; 3. Fruit thinning. Generally completed in 3 rounds, that is, 3 weeks after full bloom when peach fruits are the size of corn kernels, the first rough thinning is done; 4 weeks after flowering, remove twin fruits, deformed fruits, small fruits, shriveled and underdeveloped fruits, etc., and retain an appropriate fruit load.

5. Coloring management:

1. Bagging. Done after fruit set is finalized, its main purpose is to prevent pests, diseases, and fruit surface contamination, reduce chlorophyll content in the fruit peel, induce anthocyanin formation, and increase coloring speed and degree. The timing of bag removal is determined according to the fruit's ground color, the weather during the coloring period, and the type of bag. Generally it is done 10 days before harvest; if it is cloudy and rainy, it should be done slightly earlier. Because the growth periods of fruits in the upper and lower parts of the canopy are not consistent, lower branches should have bags removed 2 days later.

2. Branch thinning and branch tying. In the greenhouse, high temperature and high humidity lead to many water sprouts, which affect light in the lower part. Usually 2 weeks before harvest, remove upright branches on the back and overly dense branches. For drooping fruiting branches, tie them with string to the arch frame or central column, but the tying height should be at least 40-50 cm from the greenhouse roof to prevent sunburn.

3. Laying silver reflective film. After bag removal, lay silver reflective film under the canopy or on the north wall of the greenhouse, which can make full use of scattered light, diffused light, and reflected light to promote coloring of fruits inside the canopy and in the middle and lower parts.

4. Leaf removal. About 10 days before harvest, remove 3-4 shading leaves around each fruit. However, do not turn the fruit, otherwise it will cause damage to the fruit surface around the stem end or fruit drop; 5. Removing the greenhouse film. About 10 days before harvest, if it is not cloudy or rainy, the greenhouse film should be gradually removed. This can increase light and take advantage of the large temperature difference outdoors to improve fruit quality.

6. Spraying rare earth. According to reports, spraying rare earth at a concentration of 500 mg/L during the flowering and fruit enlargement stages can significantly increase the sugar content and soluble solids content in the fruit, and can also increase fruit size.

6. Supplementing carbon dioxide:

Carbon dioxide is an important raw material for crop photosynthesis. Because the greenhouse is in a semi-closed state, its composition is very different from that in nature. The carbon dioxide concentration in the greenhouse is (80-200)×10-6, while in nature it is 340×10-6. Carbon dioxide is severely deficient. In peach trees, this affects photosynthesis, causing reduced yield and fruit that is bland and tasteless, so carbon dioxide content must be supplemented. Methods that are easy to implement in production include: 1. Applying more organic fertilizer. Apply 50-75 kg of crop straw per plant, bury it into the soil, and within 1 month the average carbon dioxide concentration in the greenhouse is (600-800)×10-6; 2. Opening ventilation ports. Open ventilation ports on the south side of the facility 1 m above the ground to exchange carbon dioxide with the atmosphere; 3. Applying solid carbon dioxide. During key periods of peach tree development, use 17-20 kg per mu to meet the urgent needs of the peach trees; 4. Burning liquid petroleum, white kerosene, etc. to generate carbon dioxide, or using sulfuric acid at an appropriate concentration to react with carbonate to produce carbon dioxide; 5. Growing mushrooms. Growing mushrooms in idle areas of the greenhouse can produce carbon dioxide through microbial activity, and at the same time can increase growers' income.

7. Pest and disease control:

Because greenhouse-grown peach trees are isolated from the outside, pests and diseases are lighter than in open-field cultivation. The main pests and diseases harming greenhouse peaches are aphids, red spiders, peach brown rot, gray mold, and bacterial shot hole disease. Generally, before covering the greenhouse, spray once with 5°be lime sulfur mixture or 500 times Guoshukang solution. After petal fall, spray again with 20% methomyl 1500 times + fenvalerate 3000 times + 50% mancozeb 800 times solution. After that, spray 2-3 more times with insecticides and fungicides according to the occurrence of pests and diseases. To prevent humidity from increasing, smoke agents can also be used to control pests and diseases, such as aphid-killing smoke agent, Qingfeng No. 2 smoke agent, gray mold No. 2 smoke agent, etc.