Key Technical Points for Spring Management of Apricot Trees in Greenhouses

In winter-warm greenhouses, the fruit development period of apricot trees runs from mid-February to the end of April. This period is divided into three main developmental stages. The first stage is the first rapid growth period of the apricot tree and the new shoot growth period, lasting 28-34 days; the second stage is the pit-hardening period, lasting 8-12 days; the third stage is the second rapid growth period of apricot fruit and the new shoot growth period, lasting 20-30 days.

Management work for the first stage: After flowering, apply 0.5 kg of nitrogen fertilizer and 1 kg of phosphorus fertilizer per tree. Within two weeks after flowering, spray 0.3% urea once every 7 days. After leaf expansion, spray Jingzhun or Yashijing at 3000-5000 times dilution. After flowering, promptly ring-cut the vigorous branches of vigorous trees, 3-5 cuts per branch, with spacing of 2-3 cm. Within two weeks after flowering, spray 3 times with fruit-setting agent, 0.1% boric acid, 25 ppm gibberellin plus 0.3% monopotassium phosphate, glucose, and 300 times dilution of anti-drop color-enhancing agent to improve fruit-setting rate. Remove improperly positioned buds. When new shoots grow to 25 cm, pinch the tips, around late February to early March. Thin out small fruits at the base of fruiting branches, deformed fruits, twin fruits, and fruits damaged by pests or diseases. The maximum temperature inside the greenhouse should be 20°C-25°C, not lower than 7°C at night, with the suitable temperature being 15°C-18°C, relative humidity less than 6%, and the optimal ground temperature being 14°C-19°C. Try to increase the carbon dioxide concentration inside the greenhouse and prevent the greenhouse temperature from fluctuating sharply.

The second stage requires mastery of two key aspects: 1. Fruit setting. Leave one fruit on flower-bunch fruit branches, 1-2 fruits on short fruit branches, 2-3 fruits on medium fruit branches, and 4-6 fruits on long fruit branches. 2. Temperature and humidity control. The maximum temperature should not exceed 28°C, the daily average temperature should be 18°C-22°C, and the ground temperature at 10 cm depth should be controlled at 20°C-24°C.

The third stage requires attention to three points: 1. Fertilizer and water management. Spray 0.2%-0.3% urea plus 0.2%-0.3% monopotassium phosphate once every 7-10 days, for 2-3 consecutive sprays. 2. Summer pruning. When new shoots exceed 20 cm, pinch the tips. When scaffold branches grow to about 50 cm, bend the branches to open the angle. Promptly thin out vigorous shoots on the upper side and densely growing branches to open up the light path. Perform ring-cutting and twisting on some new shoots to promote flower bud differentiation and fruit coloration. 3. Environmental regulation. Maintain daytime temperature at 26°C-28°C, not exceeding 30°C, and nighttime temperature at 10°C-25°C to increase the day-night temperature difference. Maintain humidity at 50%--60%. Supplement carbon dioxide as much as possible, and pay attention to supplemental lighting. Under the premise of not exceeding the maximum temperature, raise the greenhouse temperature as much as possible.