Management of Apricot Trees in Greenhouses During the Growing Season and Pollination Precautions

Apricot (scientific name: Armeniaca vulgaris Lam.) is a deciduous tree. It grows on the ground, and the plant is hairless. The leaves are alternate, broadly ovate or round-ovate, with bluntly serrate margins; near the apex of the petiole there are two glands; the pale pink flowers are solitary or 2-3 together, white or slightly red. The drupe is round, oblong or flattened-round; the skin is mostly white, yellow to yellow-red, and the sun-facing side often has a red blush and spots; the flesh is dark yellow, sweet and juicy; the stone surface is smooth without pits, and the stone margin is thick with grooves. The kernel is mostly bitter or sweet. The flowering period is March-April, and the fruiting period is June-July. It is cultivated in many parts of China.

1. Fertilizer and water management: When the new shoots grow to 15 cm long, apply quick-acting chemical fertilizer, alternating with foliar spraying. Apply 50 g of urea per plant, and spray the leaves with a 0.3% urea solution or a 0.4%-0.5% monopotassium phosphate solution, spraying once every 10-15 days for 3-4 consecutive times. After August, mainly use phosphorus and potassium fertilizers, and spray the leaves with a 0.3% monopotassium phosphate solution 2-3 times. At the end of September and the beginning of October, apply farmyard manure and compound fertilizer, with 500 kg of chicken manure and 75 kg of potassium sulfate compound fertilizer per greenhouse. After covering the greenhouse, apply 100 g of urea per plant before budbreak, and after flower drop until the fruit enlargement stage apply 100 g of potassium sulfate compound fertilizer per plant once, while also spraying a 0.3% urea solution and a 0.3%-0.4% monopotassium phosphate solution every 10-15 days. Irrigate 3 times during the growing season: the first time about 20 days before covering the greenhouse, the second time after flowering depending on soil conditions, and the third time at the pit-hardening stage.

2. Environmental regulation inside the greenhouse: Cover the greenhouse with straw mats in early December. First pull up 1/3 of the straw mats, then pull up 1/2 of the straw mats, until all the straw mats are pulled up during the day in mid-December, when full warming begins, and cover the straw mats at night to keep warm. Cover the ground with plastic film 15-20 days before the greenhouse is warmed, so that the soil temperature rises slowly first, and when the greenhouse is warmed, the soil temperature and air temperature are coordinated. After flower drop, remove the plastic film to prevent high temperatures from damaging the roots.

Pollen collection

2-4 days before artificial pollination, collect flower buds that are about to open and normally developed from selected varieties with high pollination compatibility, or cut flowering branches from pollinizer trees and insert them into water bottles for water culture. Take the collected flower buds indoors, open the petals with tweezers, remove the anthers, spread them on smooth paper, and place them in a room at 20-25°C and 30%-70% humidity to dry in the shade. When the anthers crack, they can release pollen; for water-cultured flowering branches, when the anthers mature, gently tap the branches so that the pollen falls onto the paper. After collecting the pollen, sift out debris, store it in a bottle, and keep it in a ventilated, dry place for later use. The number of buds collected or the amount of flowering branches collected can be determined according to the number of flowers to be pollinated, the amount of pollen, or the variety. Because apricot pollen quantity is relatively small, generally one flower bud can pollinate three flowers.

Pollination timing

For whole-tree pollination of apricot, generally when about 25% of the flowers are open, the stigma is bright in color, and there is a large amount of mucus. The time is generally in the morning of the day the flowers open, when there are no water droplets and the stigma is fresh and moist; pollination is best then, and the fruit-setting rate is also relatively high.

Pollination methods

1. Spot pollination method: Add 3-5 times the amount of talcum powder or starch to the collected pollen, mix thoroughly, then dip a small amount of pollen with a brush or soft rubber tip and lightly smear it on the stigma. Each dip of pollen can pollinate 10-25 flowers. Focus on full spot pollination for plants with few flowers and for early-opening flowers and late-opening flowers, so as to improve the fruit-setting rate and ensure yield.

2. Spray method: Take 10-12 g of the collected dry pollen, add 5 kg of water and 250 g of white granulated sugar, mix and stir to prepare a suspension for later use. Before spraying, add 5 g of boric acid, mix thoroughly, and immediately spray with a hand-held sprayer. Spray 1-2 times when 60% of the flowers on the whole tree are open. The whole tree should be sprayed evenly, without missing any part or repeatedly spraying too much, so as to make full use of the pollen.

In addition to artificial pollination, keeping honeybees or mason bees in the greenhouse where apricot trees are planted for supplementary pollination is also a good choice for increasing the fruit-setting rate.