Detailed Explanation of Eggplant Grafting Methods and Management Key Points
Eggplant, also known as "qie", with the alternate name "luosu", is one of the few purple vegetables and is also a very common home-cooked vegetable on the dining table. In some areas of Jiangsu, Zhejiang, and Anhui, people call it luosu, while in Guangdong and Guangxi it is called aigua. It is an annual herbaceous plant of the Solanaceae family, genus Solanum, and is perennial in the tropics. Its fruit is edible, mostly purple or purplish-black in color, though there are also light green or white varieties, and the shapes include round, oval, pear-shaped, and various others.
Growing Environment of Eggplant
Temperature: Eggplant prefers high temperatures. The suitable temperature for seed germination is 25-30 °C. During the seedling stage, the suitable daytime temperature for development is 25-30 °C, and 15-20 °C at night. Below 15 °C, growth is slow and flower drop occurs. Below 10 °C, metabolism becomes disordered.
Light: Eggplant has relatively high requirements for both light duration and intensity. Under conditions of long sunshine and high intensity, eggplant grows vigorously, flower bud quality is good, fruit yield is high, and coloring is excellent.
Water: Before the first fruit sets, water demand is low. After the eggplant grows rapidly, it needs more water. Around the harvest of the second fruit, water demand is greatest, and water needs must be fully met. Eggplant likes water but fears it too; when the soil is wet and aeration is poor, root rot is easily caused, and high air humidity makes diseases more likely.
Soil: It is suitable for cultivation in soil rich in organic matter with strong water and fertilizer retention capacity. Eggplant has relatively high requirements for nitrogen fertilizer. When nitrogen is deficient, flower bud differentiation is delayed and the number of flowers decreases markedly. Especially during peak flowering, if nitrogen is insufficient, short-styled flowers increase, and plant development is also poor. Under low nitrogen fertilizer conditions, the effect of phosphate fertilizer is not very significant, and potassium absorption increases sharply in the later stage.
Eggplant Grafting Methods and Management Key Points
I. Grafting Methods
1. Cleft grafting
Japanese Torubamu rootstock should be sown 25-35 days earlier (25 days earlier if sown after germination, 35 days earlier if direct sown); Japanese wild red eggplant and Congo wild eggplant should be sown 10 days earlier; Korean CRP should be sown 20 days earlier if sown after germination, and 25 days earlier if direct sown without germination; Korean CYP and Anyang ArQ used as rootstock should be sown 3-5 days earlier. When the rootstock grows to 6-8 true leaves and the scion grows to 5-6 true leaves, when the stem is semi-lignified and the stem diameter is 0.3-0.5 cm, grafting is most suitable. Keep 2 large and robust true leaves on the rootstock, cut horizontally 3-5 cm above the ground at a point above the second true leaf, remove all other upper leaves, and then make a vertical cut with a blade. Make a vertical cleft in the middle of the rootstock stem with a thickness of 0.8-1 cm, then remove the lower part of the scion from the semi-lignified point, generally cutting off the cotyledons and the 2 true leaves above them, keeping the upper 2-4 true leaves; cut the stem into a wedge shape, with the wedge size matching the rootstock cut (wedge length 0.6-0.8 cm); then insert the scion into the rootstock cut, align them, tie with a narrow plastic strip or clip with a grafting clip, and then plant into the grafting seedling bed.
2. Approach grafting
The scion should be sown 5-6 days earlier than the rootstock. When both the rootstock and scion have grown 2-3 leaves, perform approach grafting. Select two seedlings of the rootstock and scion that are similar, make a diagonal cut with a blade 1 cm below the first true leaf on both the rootstock and scion, with the cut 0.4-0.5 cm long and half the stem diameter deep; the scion is cut upward and the rootstock is cut downward, then align the cuts of the scion and rootstock together, secure with a grafting clip, and transplant into the grafting seedling bed. The root systems of the rootstock and scion should be kept somewhat apart to facilitate cutting the scion roots after survival.
II. Grafted Seedling Management
The most critical factors for the survival of grafted eggplant seedlings are temperature and relative air humidity. When raising grafted seedlings for winter-spring eggplant (late September to early October), because the weather is cold, it is advisable to set up an electric heating hotbed or cover the seedling bed with a small arch tunnel inside a winter-warm plastic greenhouse to further preserve heat and moisture. The period for cultivating grafted seedlings of autumn-winter and overwintering eggplant occurs in midsummer and early autumn. In the greenhouse, setting up a grafting seedling bed and a small plastic arch tunnel for shading, rain protection, moisture retention, ventilation, and temperature regulation is sufficient.
Grafted seedlings should be planted and covered with a small arch tunnel immediately after grafting. When planting, set them in the seedling bed at 10 cm square spacing, then water immediately (do not let water soak the graft union); after the water seeps in, cover with soil (the soil cover must not bury the graft union, and the grafting clip should be exposed above the ground). After the whole bed is planted, cover with a small arch tunnel, and cover with plastic film to protect from rain (summer and autumn) or seal tightly to preserve heat (winter). For 3 days after grafting, maintain the temperature inside the small arch tunnel at 25 °C-30 °C during the day and relative air humidity above 95%. Shade appropriately from 10 a.m. to before 3 p.m.; after 3 days, begin ventilation and gradually expose to light; after 5-7 days, the grafted seedlings survive; after 10 days, the scion roots are cut. After about 35-45 days, the grafted seedlings are transplanted and set in the winter-warm plastic greenhouse.