Cultivation process of seedless watermelon

Seedless watermelon is planted with seeds, but this seed is not a seed in a seedless watermelon, but a seed in a triploid watermelon formed by a cross between a natural diploid watermelon and a tetraploid watermelon produced by mutagenesis. There are similarities and differences between cultivation techniques and ordinary watermelons. Let's take a look at the cultivation process of seedless watermelons.

Cultivation principle of seedless watermelon

Seedless watermelon is obtained by artificially inducing polyploidy, such as treating seeds or seedlings of diploid watermelon with colchicine (a plant base) to hinder the formation of spindle filaments and primary walls in the middle of cell division. so that the replicated genome can not be divided to the poles and form a secondary wall in the middle, resulting in the formation of double genome cells and tetraploid watermelon plants. Then the triploid seeds were obtained by crossing with the diploid watermelon plant (as the male parent). The triploid plant could not form normal germ cells because of the disordered synapsis of homologous chromosomes in the process of reduction. Then the mature pollen of diploid watermelon was used to stimulate the flower ovary of triploid plant to form triploid fruit, because its ovule could not develop into seed.

Seed cultivation of seedless watermelon

1. Artificial induction: seedless watermelon uses the method of artificially inducing polyploidy, soaking the seeds of diploid common watermelon with 0.2-0.4% colchicine (C22H26O6N) liquid for 12-24 hours, or dripping 0.2-0.4% colchicine liquid on the stem tip growth point of its seedlings at 6-7 o'clock every afternoon for four consecutive days.

2. Careful management: the treated seeds or seedlings should be washed with clean water, and the plants should be placed under astigmatism during treatment and seedling retardation, so as not to cause colchicine decomposition and destruction caused by direct sunlight. At the same time, avoid high temperature, because in the case of high temperature, colchicine is more toxic to plants and easy to cause dead seedlings, so good cultivation conditions and careful management should be given before survival.

3. Bagging pollination: tetraploid watermelon was used as female parent to produce triploid watermelon seeds with diploid pollen grains. According to the flowering habits of watermelon, small area seed production was bagged on time every afternoon, artificial pollination was carried out the next morning and markers were hung at the same time. Large area seed production needs regional isolation, and the plants of tetraploid female parent and diploid male parent are cultivated according to a certain proportion.

Seed treatment of seedless watermelon

1. Seed selection and soaking: according to the characters of the variety, the seeds were selected according to the shape, color, size and plumpness of the seeds, the tetraploid and diploid watermelon seeds were selected, and the malformed seeds, hybrids and inferior seeds were eliminated. Then, a few days before soaking the seeds, dry the seeds for 1 or 2 days. Then stir the triploid seeds in 55 ℃ of warm water, then let the water cool naturally and soak the seeds for 6 hours.

2. Artificial shell breaking: the shell breaking methods of seedless watermelon seeds can be divided into two types: dry seed shell breaking and wet seed shell breaking. The work efficiency of dry seed shell breaking is high, but it is easy to damage the seed embryo, and the seed soaking time and temperature are difficult to grasp, which affects the improvement of germination rate. The wet seed shell is easy to slip and the work efficiency is low, but the seed soaking time has little effect on the germination rate, which is easy to grasp, and the germination rate is high and stable.

3. Seed germination: the seeds soaked and broken shells were placed under the constant temperature of 33-35 ℃ to promote germination, and a certain humidity should be maintained. After 24 hours, more than 90% of those who have the ability to germinate can germinate, pick out the buds with a length of 0.5 and sow, the rest continue to germinate, and almost all the normal seeds germinate after 36 hours. The seeds that did not germinate after 48 hours have lost their vitality and do not need to germinate any more.

4. Grafting seedling: the low survival rate and slow healing rate of seedless watermelon grafting are common problems in current production, which restrict the development of seedless watermelon production and cause great economic losses to melon farmers. In order to improve the survival rate of seedless watermelon grafted seedlings and cultivate robust grafted seedlings, grafting seedlings must be carried out according to the structural and growth characteristics of seedless watermelon.

Field management of seedless watermelon

1. Soil preparation cultivation: applying 3 square meters of high quality farm manure, 20 kilograms of urea, 20 kilograms of diammonium and 20 kilograms of potassium sulfate, fine soil preparation and making beds according to row spacing of 1.7 meters. High ridge cultivation, high ridge width of 60 cm, height of about 15 cm, covering 80 cm 90 cm wide plastic film. Select planting in windless and sunny day, planting 50000plants per mu, planting with watering. The implementation of three-vine pruning, leaving the third female flower of the main vine to set fruit is the best to avoid low-node position.

2. Fertilizer and water management: 5 kg urea per mu was applied to promote seedling growth of seedless watermelon at seedling stage (before and after group plant). Generally, there was no watering or fertilization in flowering and fruit setting stage. When the watermelon is the size of a duck egg, the melon is basically stable, and the yield and quality can be improved by applying expanded melon fertilizer once, urea 15kg / mu, potassium sulfate 15kg / mu, and foliar spraying 0.2% potassium dihydrogen phosphate in the later growth stage.

3. Artificial pollination: seedless watermelon uses artificial auxiliary pollination with strong purpose, early and neat fruit setting, and consistent fruit ripening. At about 8 o'clock in the morning, the female flowers of seedless watermelon are pollinated with the male flowers of the pollinated varieties blooming on the same day. After flowering, the earlier the pollination time is, the better, no later than 10:00 at the latest. A male flower can pollinate 3-4 female flowers, pollinating evenly and lightly, so as to avoid harming the stigma.

4. Reasonable ripening: seedless watermelons can be ripened with ethephon when they need to be put on the market in advance. When the size of the fruit is considerable but not yet ripe, apply 200 mg ethephon solution per kilogram of watermelon along the melon surface before and after dusk. A small amount of neutral soap powder can be added to the solution to increase adhesion, and it can be harvested and put on the market two days later, which can be supplied to the market 3-5 days ahead of natural maturity.