Technical measures to promote pomegranate fruit setting

The flowers of pomegranate are bisexual flowers, which can be divided into complete flowers and incomplete flowers according to the degree of pistil development. The complete flower is a gourd-shaped flower or barrel-shaped flower, commonly known as "big-ass fruit flower", is the main part of the fruit; incomplete calyx tube trumpet-shaped, known as "bell-shaped flower", "pointed buttock flower", can not be fertilized and fruited. Pomegranate trees often have a large number of flowers, but they have few fruits and low yield, especially in orchards with extensive management. The main reason is that pomegranate has few complete flowers, which generally account for only about 10% of the total number of flowers, and the formation of degraded flowers is mostly due to malnutrition in the process of flower bud differentiation. Only complete flowers can set fruit, but its fruit setting rate is not necessarily high. Among the flowers in each stubble, the fruit setting rate of the first stubble was 4.3% to 6.1%, that of the second and third stubble was 10.5% to 53.7%, and that of the last stubble was 7.5% to 33.3%. Therefore, to promote fruit setting and increase yield, the key is to increase the proportion of normal flowers and the fruit setting rate.

1. Improve the nutritional status of trees

Foliar spraying 0.3%-0.5% potassium dihydrogen phosphate + 0.2% urea from July to October can improve the photosynthetic efficiency of leaves and promote the enrichment and health of branches and shoots, which is beneficial for branches to stop growing to form terminal buds and differentiate into mixed flower buds. Deep turning and hole expansion in autumn and winter, soil improvement and early application of more base fertilizer to improve the storage nutrition level of trees. It is an effective measure to promote pomegranate flowering, fruit setting, vegetative growth and flower bud differentiation to create a good water, fertilizer, air and thermal environment in topsoil. To adapt to the light-loving characteristics of pomegranate, open tree shapes such as single dry natural happy shape and three main branches happy shape are adopted to enhance light, expand the range of effective branches and buds, and improve the nutritional level of branches and buds. A large number of leaf clumps and short branches that stop growing early in spring and summer are cultivated by opening the crown, thinning branches and other plastic pruning. Through winter pruning and summer shearing, the ratio of fruiting branch to vegetative branch was adjusted to 1 ∶ 5: 10 to ensure the supply of tree nutrition to fruit.

2. extra-root topdressing at flowering stage

Spray 0.2% urea + 0.3% 0.5% borax or 500mg/l gibberellin at full flowering stage, or 0.2% urea + 400 times rare earth from early flowering to full flowering stage to increase fruit setting rate.

3. Ring cutting at flower bud stage

At the flower bud stage in the first ten days of May, 2-3 rings were cut at the base of the prosperous tree or big branch group with less flowers, and the distance between the two rings was more than 4cm, which significantly increased the fruit setting rate and promoted the flower bud differentiation in the same year.

4. Bee release and artificial pollination in orchard

Pomegranate is an insect-pollinated flower, and bee release in orchard at full flowering stage can significantly increase fruit setting rate and fruit yield. Generally, a box of bees should be placed in the middle of every 200-plant orchard and should be stocked when the temperature is above 11 ℃. Do not spray highly toxic pesticides during bee release.

If there is no bee source in the orchard at flowering stage, artificial pollination should be taken. 1) artificial pollination of flowers. Pick the blooming bell-shaped flowers, touch the blooming tube-shaped flowers and gourd-shaped flowers, and scatter the pollen on the style of the normal flowers. Can be carried out at the same time as flower thinning. 2) artificial pollen collection and pollination. During flowering, pick back the sparse flowers, remove the petals, rub a pair of flowers in each hand, and make the pollen fall off on the newspaper. After drying, gather the pollen together and shake it with a double-layer gauze bag or spray the normal flowers with a hand-held dusting machine. This method is fast and suitable for large area orchard pollination.

5. Thinning buds, flowers and fruits

Timely thinning of degraded flowers and too many young fruits can effectively reduce the ineffective consumption of tree nutrition, increase fruit setting rate, and promote fruit development and flower bud differentiation. The practice is to erase all bell-shaped buds and open bell-shaped flowers and retain tube-shaped and gourd-shaped flowers from budding to full bloom. If the gourd-shaped flowers are enough, you can also remove the tubular flowers (intermediate flowers) together. Finally, it is moderate to have 3-5 vegetative branches (with more than 100 leaves) around the fruit branches bearing normal flowers.