Key Points and Detailed Methods of Papaya (Chaenomeles) Seedling Raising Techniques
Papaya is the dried near-ripe fruit of the rose family plant Chaenomeles speciosa (Sweet) Nakai, also known as wrinkled-skinned papaya, mainly produced in Shandong, Anhui, Sichuan, Hubei, Yunnan, Shaanxi and other provinces. It has functions such as relieving cough and spasms, clearing summer heat and promoting diuresis, relaxing muscles and activating collaterals, and harmonizing the stomach and resolving dampness. In recent years, a series of products such as papaya beverages, papaya wine, preserved fruit, canned goods and cosmetics have been developed, and demand in domestic and international markets exceeds supply. The prospects for developing the papaya industry are very broad. The papaya seedling propagation techniques are introduced as follows:
1. Seed collection and seed treatment
Select fruit trees in full bearing period that are free of pests and diseases. Around mid-September each year, when most of the outer skin of the papaya fruit turns yellow, picking may begin. Remove the seeds, discard empty and shriveled seeds, then soak them in a 0.1-0.3% potassium permanganate aqueous solution for about 1 hour, rinse clean with clear water, and either sow directly or store in sand until sowing the following spring. The sand storage method is to mix seeds with clean sand at a ratio of 1:3, and store them in the open in a wind-sheltered, shady, dry place, with a pit depth of about 50cm. If there are too many seeds, bamboo sticks or corn stalks should also be used to make “ventilation holes.” The sand moisture should be such that it forms a ball when held in the hand without dripping water. Cover with about 30cm of clean sand on top. During storage, check 2-3 times each month. If mold or heating occurs, promptly move them to another pit for storage. Around mid-March of the following spring, when two-thirds of the seeds have cracked open, sowing may begin.
2. Nursery site selection and pre-sowing preparation
The nursery site should preferably be a plot of brown earth or yellow earth with convenient transportation, sufficient water sources, good drainage and irrigation, and loose, fertile soil. Before sowing, finely prepare the soil, and apply per mu 10 kg of imported carbofuran, 5 kg of carbendazim, and 15 kg of compound fertilizer.
3. Sowing
Papaya usually adopts the flat-bed drill sowing method, with a sowing rate of 30-40 kg per mu, bed width 120-150cm, row spacing 20cm, furrow depth 8-10cm, soil covering thickness 3-4cm, and path width 20-25cm. After sowing, irrigate with enough bottom water.
4. Field management
Field management of papaya seedlings mainly consists of loosening the soil, weeding, watering, and fertilizing. As long as the seeds and soil are properly disinfected and the seeds are fully mature, pest and disease control is generally unnecessary. Weeding should be done “early, when small, and thoroughly.” Avoid drought, loosen the soil regularly, and fertilize about one month after emergence. Use the furrow fertilization method once every half month, applying about 15 kg of urea per mu each time, for a total of 4-5 applications. Stop fertilizing after the Beginning of Autumn to promote lignification of the seedlings.
5. Seedling grafting
Traditionally, planted seedlings are often seedling-grown stock, which not only bears fruit late (generally starting to bear fruit in five to six years) and has low yield, but also suffers variety degeneration and relatively low economic benefit. Now most plantings use grafted seedlings, which begin bearing fruit in the third year. Several varieties selected and bred in Shandong in recent years, such as Changjun, Guohua, and Luyu, have strong adaptability, high yield (after reaching full production, yield per mu can reach more than 5000 kg, with income of nearly ten thousand yuan), and excellent quality, and can be developed and promoted on a large scale. Grafting time is generally from late August to early September, usually using the single-bud side grafting method without exposing the bud. In the following spring, check that healing is complete, cut off 2-3cm from the grafting site, promptly remove sprouts and tillers, and strengthen management. In the same year, the seedlings can grow to about 1.5m. For the small number that do not survive, use the same method in spring to graft replacements.