What Types of Watermelon Are There, Can They Be Grafted, and Greenhouse Cultivation Technique Reference

Watermelon is one of everyone's summer favorites, with many varieties and sweet, delicious juice. It can cool you down and relieve summer heat; the seeds contain oil and can be eaten as a snack food; the rind is used medicinally and has the effects of clearing heat, promoting urination, and lowering blood pressure. So what types of watermelon are there? What about watermelon greenhouse cultivation techniques and grafting techniques?

I. What types of watermelon are there?

1. Early Spring Red Jade watermelon

Early Spring Red Jade is an F1 hybrid extremely early-maturing small red-fleshed watermelon. Planted in spring, it is harvested in May and matures 35 days after fruit set. Planted in summer and autumn, it is harvested in September and matures 25 days after fruit set. This variety has a long oval appearance, clear stripes on a green background, and steady plant growth. The rind is 0.4-0.5 cm thick, the flesh is bright red, crisp, tender, and refreshing, the central sugar content is above 12.5, and a single fruit weighs 2.0 kg. It keeps well and has good market quality.

2. Black Beauty watermelon

Black Beauty watermelon is oval in shape, with a relatively small fruit and pure black rind, hence the name Black Beauty.

3. Seedless watermelon

Based on genetic characteristics, seedless watermelons can be grown artificially. They are round, with no seeds in the flesh, and must be bred every year.

4. Striped rind watermelon

Striped rind watermelon is oval, with large fruit and a rind alternating light green and dark green.

5. Te Xiaofeng watermelon

Te Xiaofeng watermelon is round, with a striped rind and yellow flesh.

6. Mibao watermelon

Mibao watermelon is spherical, with dark green rind, a waxy bloom on the surface when ripe, and red flesh that is crisp, sweet, and juicy.

7. Lebao watermelon

Lebao watermelon is round, with dark ink-green rind and red flesh that is dense and crisp.

II. Watermelon greenhouse cultivation techniques

1. Variety selection

There are many cultivated varieties of watermelon. Watermelon varieties suitable for early spring greenhouse cultivation are required to be both early-maturing and high-quality, and also to have characteristics such as easy fruit set, disease resistance, high yield, and suitability for market demand. Based on summaries from recent years, the main varieties suitable for greenhouse cultivation include Jinmei Large Fruit, Zhizun, Lidu, and others.

2. Rootstock selection

Watermelon rootstock is required not only to have good, stable compatibility with watermelon grafting, but also to have good disease resistance and no adverse effect on watermelon quality. According to observations in recent years, gourd rootstock performs poorly against acute watermelon wilt and can easily cause incalculable losses, while pumpkin rootstock performs relatively better. Therefore, pumpkin rootstock is now basically used for watermelon. At present, the better rootstocks include Zhuangsi, Pumpkin No. 2, Pumpkin Changbai Daban, and others.

3. Seed treatment

Rootstock seeds and watermelon seeds are treated the same way. Soak the seeds in warm water at 25-30°C for 48 hours. After soaking, wash the seeds several times in clean water and rub them repeatedly to wash off harmful substances on the seed surface. Then wrap them well in fine cloth and place them in a constant-temperature cabinet at 27-30°C for sprouting, or insert a thermometer and place them on a heated kang for sprouting. The sprout length is best when the seeds have just turned white.

4. Sowing technique

The sowing period for greenhouse watermelon is best around December 20 on the solar calendar. Place the sprouted rootstock seed in the middle with the embryo bud facing down, then cover with floating soil (fine sandy loam) with 1.5-2 cm of soil. Under normal circumstances, about 5 days after sowing the rootstock seeds, watermelon seeds can be sprouted. Watermelon seeds can be sprouted in a sand box.

5. Grafting technique

Grafting time: Grafting can be carried out after the cotyledons of the rootstock seeds have flattened out, which is also the best time for grafting.

Grafting method: Use the top insertion method. During grafting, remove the rootstock growing point, use a bamboo skewer at the rootstock cut, insert it diagonally downward at 45 degrees along the line connecting the cotyledons into the hypocotyl below the cotyledons, to a depth of 0.5-1 cm, with the tip of the bamboo skewer reaching the cortex on the other side of the hypocotyl below the cotyledons. Then immediately take out the scion seedling, place it on the index finger and cut it at 45° with a blade. After trimming the scion seedling, immediately pull out the bamboo skewer and insert the scion seedling along the direction of the bamboo skewer hole.

Grafting management: Keep the temperature at 25°C, and keep the low temperature at 24°C. For the first three days after grafting, keep it closed without ventilation or air exchange, so that the air humidity reaches saturation. One week before planting, lower the ground temperature to 15-13°C and the air temperature to 23°C during the day and 13°C at night, with the nighttime minimum not lower than 10°C, to harden the seedlings and bring the young seedlings close to the environmental temperature after planting.