How to pollinate watermelon artificially in greenhouse in rainy days

Watermelon is monoecious and pollinated by insects. Under natural conditions, it is generally pollinated by insect pollinators such as bees in order to set fruit normally. Watermelon in greenhouse in spring usually has female flowers from late March to early April. At this time, the outside temperature is low and there are fewer insects, so the greenhouse still needs to be relatively closed. Watermelon often cannot set fruit normally due to lack of pollination media, and the natural fruit setting rate is low. Generally, artificial pollination measures should be taken to improve the fruit setting rate.

1, select the appropriate variety. Watermelon cultivated in greenhouse in early spring should be of good quality, resistant to weak light and easy to sit under high and low temperature conditions. Suitable varieties of small fruit mainly include early spring ruby, Chunguang, Texiaofeng, Black Beauty, Huang Xiaoyu and so on. The intermediate fruit varieties are Zaojia, Xin Jing 1 and Shenmi.

2. Choose a good place to sit on the melon festival. The location of the melon festival depends on the variety and weather conditions. When the main vine of small fruit watermelon has 18-20 nodes, the second female flower on the node 10- 12 or the first female flower on the sub-vine is selected for pollination. Watermelon with medium fruit has 20-25 nodes on the main vine. Select the second female flower of node 13- 15 or the first female flower on the vine for pollination. When the plant growth is weak, the melon can be delayed appropriately; On the contrary, the melon festival can be advanced.

3. Choose female flowers and male flowers. The quality of female flowers has a great influence on fruit development, which requires that female flowers have long and thick fruit stalks, large ovaries, normal appearance, light green and shiny peel, dense villi and good development. Male flowers are required to be healthy and disease-free, fully mature and have more pollen. It is best to choose male and female flowers that bloom on the same day nearby for artificial pollination, so that the fertilization rate is the highest. The male and female flowers that open on the first day and the male and female flowers that open on the second day still have fertilization ability after pollination; Female flowers that have been in bloom for 2 days are sterile.

4. Determine the pollination time. The best pollination time of watermelon in greenhouse is 7-9 am on sunny days, when the physiological activities of female stigma and male pollen are the most vigorous. The time is too early, the pollen has not dispersed, and it is not suitable for pollination; After 10 hour, with the rapid increase of temperature in the shed, the pollen vitality gradually decreased and was completely lost around noon. Pollination can be delayed in rainy days, or the male flowers that can bloom the next day can be taken back in the afternoon and placed indoors in dry and warm conditions, and then pollinated by the female flowers after opening the next morning. Pollen survival rate is low in rainy and cold weather, so pollination should generally be avoided in this weather. Generally speaking, the female flowers with yellow pistils before sunset the day before can be pollinated the next morning.

5. Artificial pollination. Flower transfer method: pick the open male flowers, remove the petals with tweezers or turn them back to expose the stamens, then gently lift the female flowers to expose the stigma, and gently rub the stamens on the stigma of the female flowers to make the stigma covered with pollen. Pollen should be coated evenly, otherwise deformed melons are easy to appear. Generally, a male flower can pollinate 2-3 female flowers. Brush dipping method: pick the male flowers that opened that day, concentrate the pollen in a clean container, then dip the pollen with a soft brush, aim at the stigma of the female flowers, and gently smear it several times until the stigma has obvious yellow pollen. After pollination, the date of pollination is marked by putting a tag or inserting sticks of different colors beside the pollinated flowers, which is convenient for harvesting mature melons in batches according to the number of days after pollination or the accumulated temperature required for watermelon fruit development.

6. Check the pollination effect. On the afternoon of the second day after pollination, if the flower stalk of the female flower is elongated or bent and the ovary is obviously enlarged, it indicates that pollination is successful; If the stem is still straight up or forward, it means that it is not successful, and the third female flower of the main vine or the second female flower of the secondary vine should be artificially pollinated again.

In addition, when watermelon blooms in greenhouse, we should keep sufficient light and high night temperature. After artificial pollination, the temperature is low at night, which is easy to cause fruit drop or affect fruit expansion. About 7 days after pollination, the melon is still and can be irrigated with fertilizer and water. When the young melon grows to the size of an egg, each plant should choose the well-developed young melon 1 plant (about at the leaf of the main vine 12- 14), and the main vine can be slightly sprained in the first three sections to control the overgrowth and promote the expansion of the melon.