Growing Seedlings And Pollination Of Watermelons

2024 Author: Sebastian Paterson | [email protected]. Last modified: 2023-12-16 13:47

Read the previous part. ← Watermelon hybrids for our climate

Pollination of watermelons

Now about the pollination of watermelons. As I mentioned, watermelon has both male and female flowers.

A female flower immediately has a small fruit, it must be pollinated on the first or second day after the flower blooms.

To pollinate the female flower, the male flower is plucked, the petals are carefully removed and the anthers are applied several times to the stigma of the female flower. The best temperature conditions for normal fertilization are + 18 … + 20 ° С in the morning and + 22 … + 25 ° С in the afternoon.

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If on the eve of pollination the night temperature was below + 12 ° C, manual pollination does not work. It is necessary to pollinate in the early hours, because in the morning hours (from 6 to 10 o'clock) the pollen and stigma are most active, therefore, the best fertilization of the ovary occurs. Watermelon berry growth will begin only after pollination.

The first male flowers open in 7-12 days after the start of branching, and female flowers - in 10-15 days. The length of the growing season of the variety depends on the period of disclosure of female flowers, the time of disclosure of male flowers does not affect it. Female flowers are located mainly on the main stem and branches of the first order. If we consider the flowers of watermelon from the point of view of biology, then everything is somewhat more complicated here, since there exist: a male, purely female flower, without stamens and a pistil hermaphrodite. NI Vavilov also believed that watermelons have incomplete hermaphrodism.

If we talk about the number of fruits per plant, then cultivated varieties of watermelons usually develop 2-4 and a maximum of 5-8 fruits per plant. However, there are several times more female flowers on a plant (from 15 to 60). The number of male flowers reaches 400-600, and even more flowers on small-fruited varieties. So the amount of fruit that can be obtained from one plant is tied to the variety.

Wrongly, some believe that watermelons are pollinated only by bees and bumblebees. Watermelon pollinators can be up to 150 different species of insects. It turned out that ants visit watermelon flowers before all other insects - at the first moment of their disclosure, at about 6 am. They help to get an early harvest, so there is no need to destroy ants.

Not everything is so smooth with the bees. Insects visit male flowers more often, since pollen serves as an excellent food for insects, because more than a hundred useful substances are found in it, including proteins, fats and many vitamins. In order for a full-fledged pollination of a watermelon to take place, a bee must visit a female flower up to 30 times. All pollination methods can be considered to be good. The watermelon flower is, of course, not the flowers of the scented tobacco, which are only pollinated by moths, but the flowers of the watermelon are not very attractive to bees compared to flowers of other crops or weeds.

Therefore, the neighborhood of watermelon with honey plants should be avoided, and honey weeds should be destroyed during the flowering period. And manual pollination must be carried out correctly. For full pollination, the pistil should get from 500 to 1000 pollen grains. If less pollen is ingested, twisted (ugly) fruits may form.

The pollination process is not easy. Once on the stigma of the pistil, the pollen grain begins to germinate. A long pollen tube develops from the vegetative cell (its growth is stimulated by the pistil auxins), which grows along the tissues of the column to the ovary and then to the ovule. At this point, two sperm are formed from the generative cell, which descend into the pollen tube. The pollen tube enters the ovule through the pollen duct, its nucleus degenerates, and the tip of the tube ruptures, releasing male gametes.

The sperm enter the embryo sac. One of the sperm fertilizes an egg to form a zygote. The embryo of a new plant organism is formed from the diploid zygote. The second sperm fuses with the central diploid nucleus or with two polar nuclei, forming a triploid cell, from which the nutritive tissue, the endosperm, subsequently arises. Its cells contain a supply of nutrients necessary for the development of the plant embryo.

After fertilization, the ovule grows and turns into a seed, and as a result of the growth of the ovary of the pistil, a fruit is formed. The walls of the ovary become the wall of the fetus - the pericarp, inside which there are seeds. Why did I dwell on the theory of pollination in such detail? The fact is that if pollination does not occur, and it takes place inside the flower in two stages, and at a certain temperature, then you will not have watermelons.

And the sooner this process takes place, the earlier the harvest will be, so this is a very important stage. And here much depends on the effect of heterosis of the hybrid in this direction, because early maturing heterotic hybrids can ripen 30 days after pollination, and ordinary varieties - after 45-50 days. So pick the right hybrid for yourself.

Seedlings will speed up the harvest

A few notes about the peculiarities of growing watermelon seedlings. In general, the seedling method helps to avoid damage to watermelon seedlings by wireworms, which can destroy up to 60-70% of seedlings. This is a reminder for those who like to plant everything without seedlings, and even with untreated seeds.

The composition of the soil-soil mixture for seedlings is as follows: peat - 76%, compost - 10%, sand - 10%, biohumus - 4%. Such a standard universal composition is recommended by the Botanical Garden, they always have good soils on sale. You can use other compositions, but the presence of vermicompost is desirable. You can add sawdust to the soil, but not conifers, coconut substrate, the main thing is that the substrate does not thicken after watering and does not form a crust. Watermelon organically dislikes dense soils.

Sow one seed at a time in pots filled with 2/3 wet substrate to a depth of 1.5-2 cm. The rest of the soil is added gradually throughout the entire period of growing seedlings. This promotes the formation of additional roots in plants.

After the end of sowing, the pot is watered with a small amount of water. The next watering is carried out after the emergence of shoots. During the entire growth of the seedlings, it is watered when the substrate dries up. Daily watering may become necessary as the seedlings reach transplantable age.

During germination, the temperature must be maintained within + 25 … 30 ° C. When seedlings appear, the temperature is reduced within 6-9 days to + 16 … 18 ° C. During the period of plant growth, the temperature should be + 20 … 25 ° С during the day, and + 16 … 18 ° С at night. Seedlings should not be more than 24-28 days old before planting. Seedlings are fed 1-2 times a week at the rate of 10-15 g of ammonium nitrate and 18-20 g of monopotassium phosphate per 10 liters of water per 1 m². 6 days before planting, the seedlings begin to harden, reducing the daytime temperature for 1-2 hours by 2 … 3 ° C, and before planting in the greenhouse - to the real greenhouse temperature for 5-6 hours.

Hardened plants are more resistant to low temperatures, they develop new roots much faster than unhardened plants, however, too hardened plants grow more slowly and in some cases never fully recover. So don't overdo it with hardening. It must be remembered that young watermelon plants are stressed if the roots are damaged even minimally during transplantation.

Read the next part. Soil temperature and watering watermelons →

Vladimir Stepanov, Doctor of Biological Sciences

Photo by E Valentinov