Cultivation Methods for Loquat in Greenhouses in Northern China

Loquat is rich in nutrients and has a unique flavor; its flowers, fruit, leaves and roots can all be used medicinally, but it does not store or transport well, and it is a specialty fruit tree of southern China. At present, the Institute of Forestry and Pomology of the Beijing Academy of Agriculture and Forestry Sciences has introduced the early-maturing loquat variety Zaozhong No. 6 and cultivated it in a greenhouse, avoiding the low temperatures of Beijing's winter and enabling loquat to grow in the Beijing area. This variety is extremely early-maturing, has strong stress resistance and adaptability, performs well in yield, and shows no obvious alternate bearing. Its cultivation techniques are described below.

1. Botanical characteristics: Zaozhong No. 6 fruits early, with a high natural fruit-setting rate and no need for manual intervention. It begins to bear fruit 2 years after planting, with a yield of 0.5-1 kg per tree; 3 years after planting it bears fruit fully, with a yield of 4-5 kg per tree. The fruit is obovate, with an average single fruit weight of 40.5 g and a maximum fruit weight of 45 g. The fruit contains an average of 6.2 seeds, and the edible rate is 76.8%. After bagging, the peel and flesh are orange-red, with few rust spots; the peel is medium-thick and not easy to peel. The flesh is tender and tastes sweet and sour. In unbaged fruit, 95% of the fruit develops sunscald spots, covering an area of more than 50%. The fruit is smaller than that grown in the open field, but the flavor is better. In the greenhouse environment, new shoots grow 4 times a year, in early February, May, August and November respectively; the start of the flowering period is advanced to early August, and the flowering period lasts more than 2 months.

2. Main cultivation techniques:

1. Planting. Plant in the greenhouse in north-south rows, using close planting, with a row spacing of 2×1 m and 5 trees per row. Plant on a sunny day in spring, choosing 1-year-old seedlings.

2. Temperature management. Cover the greenhouse with plastic film in early November, begin heating around November 20 to ensure the minimum nighttime temperature does not fall below 10℃, stop heating around March 20, and at the same time take care that the midday temperature is not too high; ventilate promptly to keep the greenhouse temperature from exceeding 30℃, and remove the film and covers in May.

3. Light management. Young seedlings like scattered light; after planting, install shade netting for shade when the light is strong. But mature trees require sufficient light. Direct sunlight easily causes sunscald, so appropriate close planting is necessary, and shade netting should be installed for shade in summer.

4. Water and fertilizer management. Loquat prefers an environment with moist air and abundant water. During fruit development and new shoot growth, apply light watering; during fruit ripening, control water appropriately to avoid adverse consequences such as fruit cracking, reduced fruit quality and delayed ripening.

Loquat is a fruit tree with a very high fertilizer requirement, has no obvious dormant period, and produces 3-5 flushes of shoots per year, so its fertilizer demand is large. Young trees are fertilized 5-6 times a year, once every 2 months, mainly with nitrogen fertilizer, applying light fertilizer frequently. Mature fruiting trees are fertilized 4 times a year. The first time is from mid-July to mid-August before flowering, applying 5-10 kg of livestock and poultry manure per tree. The second time is from late November to early December, applying 4-5 kg of farmyard manure, 0.8-1 kg of compound fertilizer, 0.8-1 kg of calcium magnesium phosphate fertilizer and 0.3-0.5 kg of urea per tree. The third time is during the fruit expansion period, when the demand for potassium is greatest, 2.7 times that of nitrogen. In January of the following year, during the rapid fruit expansion period, apply quick-acting fertilizers mainly of potassium and phosphorus, and carry out foliar feeding. The fourth time is the post-fruit fertilizer, in late March of the following year, applied before harvest or within 1 week after harvest, mainly with nitrogen fertilizer plus some organic matter fertilizer.

5. Flower and fruit management. Loquat has a relatively long flowering period; in the greenhouse, the first flowers are mainly used, which not only gives larger fruit with good quality, but also enables loquat to set fruit early and ripen early. In the greenhouse, thin the fruit as early as possible, first removing deformed fruit, diseased or insect-damaged fruit, or poorly developed young fruit, leaving 5-6 fruit per cluster. When thinning, try to keep the fruit hidden among the leaf clusters. After the final fruit thinning, bag the fruit with special grape bags. Start from the top of the tree, then work downward toward the outer canopy; the paper bags can be tied with straw or fastened with paper clips, and when bagging be sure to make the bag bulge to allow ventilation.

6. Training and pruning. Do not prune heavily during the young tree stage; mainly use branch bending, carried out from one month to one and a half months before the first flowers, to promote flower bud differentiation and ensure early yield of loquat. After loquat harvest, prune the fruiting trees, mainly by thinning branches, with the aim of ventilation and improving light conditions, gradually training the loquat tree into a modified central leader form.

7. Pest and disease control. The main diseases that easily occur in the greenhouse are sunscald and leaf tip scorch. Therefore, while using facilities such as shade netting to prevent sunscald, strengthen soil improvement and fertility management to improve disease resistance. The main insect pests include red spider mites and aphids, which can be controlled with high-efficiency, low-toxicity pesticides.