Cultivation Techniques for Large Flat Apricot in Semi-Arid Regions

The large flat apricot is an economic forest tree species unique to China, characterized by strong adaptability, early fruiting, long lifespan and high comprehensive utilization value. In Kalaqin Town, Jianping County, located in the semi-arid region of northern Liaoning, an orchard was established as early as 1985 in Dayingzi Village, covering an area of 300 mu; it is now growing well, in its full-bearing period and has achieved high economic returns. Since 2002, Kalaqin Town has planted another 456 mu of large flat apricot in Kanzhangzi Village, but due to drought and low rainfall, poor soil and low-level planting techniques, the survival rate in the first year was less than 40%, and it took another two to three years of replanting to reach the standard; however, the apricot orchard had poor uniformity, low yield and poor returns. In view of this, we summarized past experience and lessons, and through practice explored techniques suitable for planting large flat apricot in arid regions to increase the survival rate. The report is as follows:

1. Select high-quality seedlings. Selecting high-quality seedlings is the key to the success or failure of orchard establishment. High-quality large flat apricot seedlings refer to first-grade or above grafted seedlings of the "two roots and one trunk" type. The standard for first-grade seedlings is a seedling height of 80-90 cm, aboveground trunk diameter of more than 0.8 cm, root length of 20-25 cm, no fewer than 5 lateral roots larger than 5 cm, and no disease, with the graft union healing well.

2. Timely and standard site preparation. ① Change the timing of site preparation. The northwestern region of Liaoning is a severely arid area, with an average annual precipitation of only 465 mm, strong winter wind and sand, and winter precipitation of less than 15 mm. According to past practice, pits were mostly dug during site preparation in the previous autumn. After digging, through a winter of wind and sun, all the excavated soil had dried out, and the soil around the pits had also dried thoroughly to a depth of more than 20 cm. When planting in spring, which coincides with the spring drought, it is very difficult to ensure moisture. Increasing irrigation volume would, first, raise planting costs, and second, the more water applied, the lower the soil temperature, which is not conducive to seedling recovery. Digging pits in spring can overcome the above drawbacks, and the survival rate can reach more than 95%. Therefore, autumn pit digging should be changed to spring pit digging, and the specific time should preferably be about one week before planting.

② Site preparation standards and technical regulations. For plots with a soil layer more than 1 m thick, dig pits with a diameter of 60 cm and a depth of 60 cm; for plots with thin soil, dig pits with a diameter of 80 cm and a depth of 100 cm, placing topsoil and subsoil separately. Apply 30-50 kg of high-quality farmyard manure and 1.5 kg of superphosphate per plant, in alternating layers of manure and soil, and backfill the pits entirely with topsoil; if insufficient, supplement with surrounding topsoil or imported soil, tamping while backfilling. Finally, leave a planting level 20 cm below the orchard surface, and irrigate each plant with about 30 kg of water.

3. Planting time. Kalaqin has dry, windy winters and is also prone to freeze damage, so spring planting is preferable, and the best time should be mid-to-late April. Too early, the soil temperature is low, sprouting is slow, and seedlings are prone to dieback; too late, because the trunk and buds of the seedlings sprout earlier than root activity, the survival rate is low.

4. Treatment of seedlings. For seedlings transported over long distances, cover them with tarpaulin during transport to prevent dehydration. Before planting, soak the whole plant for 24 hours, then trim the root wounds smooth, dip them in 400 mg/kg rooting powder for 2-3 minutes, and then coat them with mud slurry before planting.

5. Planting techniques. ① Plastic bag planting technique. Take a plastic bag with a diameter of 40-50 cm and a height of about 30 cm (a convenience bag may be used). First put in a little cooked soil, place the seedling root system into the bag and spread it out, continue adding soil, and at the same time gently lift the plastic bag so that the soil is filled firmly, until the soil surface in the bag is level with the graft union of the seedling. Then tear two holes about 5 cm in diameter at the bottom of the bag facing the large lateral roots, so that the root system can later grow out through the holes and water can exchange inside and outside the bag. Then carefully place the bag into the planting pit, backfill topsoil until level with the soil in the bag, and water thoroughly in two applications (giving priority to thoroughly watering the soil in the bag). Finally, after the water settles, gather the bag opening, cover with soil to about 15 cm above the graft union, tamp firmly, and build a tree basin. The plastic bag can be gradually broken down in the second year when fertilizing. This technique was tested in 2003 in Zhujiawopu Village, Kalaqin Town, and the survival rate reached 95%.

② Small-mouth bottle planting technique. Take a small-mouth bottle (preferably a 500 mL medical drip bottle) and fill it with water, place it on one side of the planting pit, fix it with soil at a 40-degree tilt from the vertical direction, insert one long lateral root of the seedling into the water bottle down to the bottom, and at the same time carefully fill with 20 cm of soil, pour one bucket of water, and after the water infiltrates, cover with soil to 15 cm above the graft union and tamp firmly. Where conditions permit, it is best to also cover with 1 m square plastic film (press the edges and center of the film firmly with soil, forming a shape lower inside and higher outside to facilitate rainwater infiltration). This method was tested in 2004 in Dayingzi Village, Kalaqin Town, and the survival rate was 94%.

6. Management techniques after planting. ① Mulching the tree basin with film. After planting and watering thoroughly once, the tree basin should be covered with plastic film, size 100 cm x 90 cm, with the edges pressed firmly with soil, and the hole where the trunk passes through sealed firmly with soil. This helps rapidly raise the soil temperature.

② Trunk heading and bagging. After planting, the trunk should be headed above a plump bud at 60-70 cm, side branches should be cut off if already branched, and a plastic bag with a diameter of 5 cm and a length of 40 cm should be used for bagging, with the lower opening and the middle of the bag tied tightly. When the new leaves grow to the size of a thumbnail, tear the bag open on cloudy days or in the evening for ventilation, and remove the film bag after 4-5 days.

③ Strengthen soil, fertilizer and water management. In early June, apply nitrogen fertilizer once, 50 g per plant, making 3-4 holes 20 cm deep at 15-20 cm from the trunk, place the fertilizer in them, water thoroughly and then seal the holes. When fertilizer and water are sufficient in the planting pits, weeds grow vigorously and should be removed in time; covering the cut weeds in the tree basin and covering with a thin layer of soil can effectively prevent weeds from competing with young large flat apricot trees for water and fertilizer.