Environmental Management Techniques for Protected Apricot Cultivation

1. Regulation of temperature and humidity: Hang 3 thermometers inside the shed on the east and west sides and in the middle respectively, at about 1.5 m above the ground. An ordinary thermometer and maximum and minimum thermometers can be placed respectively. During the bud-forcing stage, record the temperature once each day at 8:00, 12:00, 14:00 and 20:00. During the flowering stage, observe once every 1-2 hours. To measure the air humidity inside the shed, a wet-and-dry bulb hygrometer can be used. The suitable temperature and humidity for each phenological stage are shown in the table below:

Regulation of temperature is mainly achieved by opening and closing the ventilation openings. Before flowering and during the flowering stage, if the temperature does not meet the requirements, temporary heating measures can be used. Relative air humidity is regulated by measures such as ventilation, covering with plastic film, changing the temperature and controlling irrigation.

2. Supplementary lighting: Apricot is a light-loving tree species. Within the allowable temperature range, light inside the shed should be increased as much as possible. The straw curtains should be removed early and put down late to increase the lighting time. Choose drip-free film with good light transmittance and clean off dust in time. In addition, the following methods can also be used for supplementary lighting.

(1) Using incandescent lamps to increase light: At the highest point of the shed ridge, hang one incandescent lamp of more than 60 watts about every 4 m, at a height of about 2 m above the ground. After covering with straw curtains in the evening, turn on the lamps immediately, and turn them off at 22:00-24:00. Supplementary lighting is also needed on cloudy days. Iodine-tungsten lamps have a better effect.

(2) Hanging reflective screens: Hang a 2 m wide polyester aluminized film as a reflective screen on the rear wall at the north side of the solar greenhouse, reflecting sunlight that strikes the rear wall to the front, which can significantly improve the lighting conditions inside the shed.

(3) Laying reflective film on the ground: One month before fruit ripening, lay polyester aluminized film under the canopy to reflect light shining on the ground to the lower part and inner canopy of the tree, which can improve the photosynthetic capacity of leaves and promote fruit coloring.

3. Regulation of carbon dioxide concentration: In order to make the carbon dioxide concentration inside the shed reach or exceed the natural state and facilitate normal photosynthesis of apricot trees, the carbon dioxide concentration inside the shed should be regulated. There are mainly the following 3 methods:

(1) Ventilation and air exchange: In winter (November to February of the following year), ventilation is generally carried out at about 9:00 on sunny mornings, postponed by 1 hour on cloudy days, and can be appropriately advanced in spring. This method is the main way to regulate carbon dioxide concentration.

(2) Using a carbon dioxide generator: Using the principle that dilute sulfuric acid and ammonium bicarbonate react chemically to release carbon dioxide, place a relatively large plastic container inside the shed as a carbon dioxide generator. First put in ammonium bicarbonate, then add dilute sulfuric acid in portions. The bubbles produced during the reaction are carbon dioxide. When diluting sulfuric acid, be sure to slowly pour 1 part concentrated sulfuric acid into 3 parts water, stirring thoroughly with a plastic or glass rod while pouring. Never pour water into concentrated sulfuric acid, to prevent sulfuric acid from splashing and injuring people. The carbon dioxide concentration inside the shed needs to be 1000-1300 ml/cubic meter on sunny days and 500-1000 ml/cubic meter on cloudy days. This method is not suitable at low temperatures or on cloudy days.

(3) Applying solid carbon dioxide: Increase its concentration by applying solid carbon dioxide fertilizer in advance. Each mu of greenhouse can be applied with 40 kg of solid carbon dioxide, with a valid period of 90 days and a high-efficiency period of 40-60 days. Generally, it is used 5 days before flowering. The method is: first open a strip-shaped trench 2 cm deep, then evenly apply the solid carbon dioxide and cover with soil, but do not firm it. Solid carbon dioxide can also be buried underground together when covering with plastic film.