Detailed Explanation of Key Cultivation Techniques for Kate Apricot in Simple Plastic Greenhouses

The protected cultivation of Kate apricot in simple plastic greenhouses reaches maturity 30 to 40 days earlier than open-field cultivation, and economic benefits increase by 15 to 20 times.

1. Structure of the simple plastic greenhouse. The greenhouse built is a north-south arched greenhouse, with a span of 10 m, a length of 60 m, a ridge height of 2.5 m, and a shoulder height of 1.5 m. Reinforced concrete columns are used as uprights, and bamboo poles are used for the arches and suspension beams. There are 5 rows of uprights in total, with 2.5 m between the main upright rows. The spacing between uprights in the edge rows is 1 m, and the spacing between uprights in the middle 3 rows is 3 m. Above the middle 3 rows of uprights, one suspension beam is installed for each, and between every two uprights, a 20 cm hanging post is placed on the suspension beam every 1 m. The arches are mounted on the edge uprights and hanging posts every 1 m. The greenhouse film uses drip-free film, and adjacent film widths overlap each other. A film-pressing line is used to press tightly at the center of every 2 arches. During ventilation, it is sufficient to open a gap at the overlap of the two film widths at the shoulder of the greenhouse.

2. Cultivation and management techniques. Soil conditions. The experimental site is sandy loam soil with a good drainage and irrigation system, an organic matter content of 0.60% to 0.78%, and a pH value of 7.1 to 7.3. Variety arrangement. The main cultivar is Kate apricot, with Italian No. 1 used as the pollinizer, at a ratio of 5:1. Planting density. Planned close planting is adopted. At planting, the plant-row spacing is 1.0 m x 2.5 m. As the canopy continues to expand, when the canopy becomes closed, every other plant is thinned out, changing the plant-row spacing to 2 m x 2.5 m. Training and pruning. A small central-leader delayed-open form or natural open-center tree form is selected. For ease of management, the trunk height can be raised appropriately, but not more than 50 cm. Select 3 to 6 vigorous branches as main branches. Tree height should be controlled to 30 to 35 cm below the greenhouse film. Pruning is mainly done during the growing season. Before budbreak, reasonable notching and scoring are carried out at branch-deficient positions. During the budbreak stage, remove overly dense buds and water sprouts in a timely manner, and bend main branches or large fruiting branches with too-small angles to 60 to 70 degrees. When new shoots grow to 15 to 20 cm, promptly cut the tips and pinch them to limit growth and improve light conditions in the tree. After harvest, remove drooping branches, overly dense branches, crossing branches, and overlapping branches, and cut back overly weak branch groups. In autumn, continue to bend branches to open angles and pinch overlong autumn shoots to promote branch maturity. In winter, light pruning is the main practice, removing overly dense branches, diseased and pest-damaged branches, and thin weak branches, and cutting back overly tall and overly large fruiting branch groups. Except that long fruiting branches exceeding 50 cm in length should be short-cut, generally medium and short fruiting branches are not short-cut. Time for covering and uncovering the greenhouse. The suitable time for covering the greenhouse is late December. At the end of April, when the daily average temperature reaches above 15 degrees C and the fruit is close to maturity, uncover the greenhouse. Temperature management. Cover the tree with film 20 to 30 days before covering the greenhouse, which can keep the soil temperature relatively high after covering and avoid adverse effects on tree growth and development caused by high air temperature and low soil temperature. Generally, covering with film 20 to 30 days before covering the greenhouse can increase the early soil temperature after covering by 2 to 3 degrees C. For the temperature in the simple plastic greenhouse, the requirement is 10 to 20 degrees C at the budbreak stage, 12 to 23 degrees C at the flowering stage, 15 to 24 degrees C at the young fruit stage, 12 to 28 degrees C at the fruit enlargement stage, and 22 to 32 degrees C at the fruit ripening stage. Temperature regulation can be achieved by uncovering and covering straw mats and opening and closing ventilation openings. Soil, fertilizer, water, and humidity management. After covering the greenhouse, apply 0.5 to 1 kg of NPK ternary compound fertilizer per tree, water thoroughly at the same time, and spray the canopy with 5% urea to improve the tree's nutritional level and the relative humidity in the greenhouse. During the flowering stage, spray 0.3% borax. After fruit set, at the pit-hardening stage, and at the fruit enlargement stage, spray Kenyi active bio-organic fertilizer 3 times consecutively to enhance stress resistance, increase the fruit-setting rate, and reduce physiological fruit drop. At the fruit enlargement stage, in combination with watering, apply 0.20 to 0.25 kg of potassium sulfate per tree to increase fruit size and improve fruit quality. In August and September, apply 50 kg of organic fertilizer per tree to improve the physical and chemical properties of the soil and increase the level of stored nutrients in the tree.

Flower and fruit management

① Artificial pollination. The relative air humidity in the greenhouse is high, pollen does not disperse easily, and there are few pollinating insects, so the natural fruit-setting rate of Kate apricot is low. Therefore, artificial supplementary pollination should be carried out. After flowering, from 8 to 11 a.m. each day, use a writing brush to pollinate flower by flower;

② Strict fruit thinning. If Kate apricot sets too much fruit, the tree vigor is very likely to weaken. The amount of fruit retained should be determined according to tree age, tree vigor, and the strength of fruiting branches. Generally, long fruiting branches retain 3 to 4 fruits, medium fruiting branches retain 2 to 3 fruits, and short fruiting branches retain 1 to 2 fruits or no fruit. Fruit thinning is generally carried out about 20 days after flowering. Application of growth regulators. Because Kate apricot in plastic greenhouses has a high planting density and grows quickly, controlling vigorous growth and promoting flowering becomes the key to protected cultivation. Using paclobutrazol to control the canopy has a relatively good effect. Method of use: for young vigorous trees, spray 300-fold 15% paclobutrazol solution twice in mid-to-late July. Pest and disease control. One week after covering the greenhouse, spray 5 degrees Be lime sulfur mixture once, and before budbreak spray 3 degrees Be lime sulfur mixture to control overwintering pests and diseases. At the bell flower stage, spray once with Yashiyicijing plus Nisuolang to eliminate aphids and red spider mites. During the growing season, depending on the pest and disease situation, spraying 1 to 2 times with insecticides and fungicides is sufficient.