How to improve the fruit setting rate of pear trees

1. Flower and fruit protection they are two technical measures with very different meanings, and the purpose is to improve the fruit setting rate. These two measures are skillfully combined on the same tree to ensure that there is enough fruit on the tree for a bumper harvest.

Protecting flowers and fruits is by no means an emergency measure that the flowers on the tree are about to bloom. Because the flower buds of pear trees began to differentiate in the middle of June of the previous year, after a long time, the flower organs gradually formed and did not bloom until March of the following year. If we do not pay attention to the prevention and control of diseases and insect pests, especially the pear army worm and pear black spot, which cause a large number of fallen leaves, the leaves of the pear tree will basically fall off in August, and when the temperature is suitable from September to October, when Rain Water is sufficient, new leaves will be issued and secondary flowers will bloom at the same time. The flowers that should bloom in the first year of the second year will be finished in the first year, and naturally there will be no flowers in the second year. Some pear orchards will have more leaves in August, because they do not have enough leaves to make nutrients. Flower bud differentiation is not sufficient, although there are many flowers in the second year, but not much fruit. Thus it can be seen that the decisive measure to protect flowers and fruits is to protect leaves.

Flower thinning, fruit thinning, flower protection and fruit protection are complementary technical measures. Most pear varieties are easy to form flower buds, more flowers and high fruit setting rate. The fruit bears too much, first, the fruit is small, the economic benefit is low, and the other is to cause the big and small years, so we must emphasize thinning flowers and fruits.

2. Artificial pollination pear trees are cross-pollinated fruit trees. The same variety of flower pollination, fruit setting rate is very low. If there are no pollinated varieties, or the number of pollinated varieties is insufficient, or the selected pollinated varieties are improper, the florescence of the main varieties meets or overlaps with that of the main varieties, or the initial flowering age of the main varieties is different from that of the pollinated varieties, or it is cloudy and rainy during the florescence, which affects the normal pollination. In these situations, if artificial pollination can be carried out, the fruit setting rate can be greatly increased and a better yield can be obtained under unfavorable conditions.

Although only 10 pollen grains fall on the stigma, they enter the ovary to fertilize and form seeds. However, the hormones produced by pollen grains that enter the style and do not reach the ovary can stimulate the cell division of young fruits. Therefore, the more pollen grains fall on the stigma, the more likely the fruit is to grow into a large fruit. The experiment showed that when 300 pollen grains were dropped on 5 stigmas of a flower, the young fruit had the most cell division and the young fruit was larger. With the decrease of pollen grains, the young fruit becomes smaller accordingly. Poor pollination and fertilization not only affect the size of the fruit, but also often increase the number of crooked fruits. With the development of market economy, it is necessary to popularize artificial pollination as a conventional technology.

The main results are as follows: (1) during the period of pollination, the flowering flowers have the ability to fertilize for 5-7 days. According to the survey, pollination is better as soon as possible after flowering. After the fourth day of flowering, the fruit obtained by pollination developed poorly, the fruit was small, and the fruit setting rate decreased obviously after 5 days. The pollen of pear germinated about 50% in 1 hour and 80%-90% in 2-3 hours under the condition of 15-17 ℃, and almost all of them could invade the stigma after 3 hours. This shows that under the condition of normal temperature, the rain 3 hours after pollination has little effect on fruit setting. Pollination can be done from 8 a.m. to 6 p.m. If the temperature is high at noon, the pollen germinates faster and the effect is better.

(2) Pollen collection and treatment the pollen collected should be pollen from different varieties of trees. Several varieties of mixed pollen can be used in production. It is best to pick budding buds. Buds that are too tender are of poor quality. After picking back the flowers, remove the pink anthers from the buds as soon as possible, spread them on the paper and dry them, so that the yellow pollen in the anthers can be dispersed. If you are in urgent need of pollen, you can dry it in a 20-25 ℃ incubator, or put a 15-watt lamp in a human cardboard box to dry the pollen, speed up the splitting of the anther and make the pollen disperse. Pay attention to the temperature should not exceed 25C, the temperature is too high to lose the germination power of pollen. If it is more than 30C, the pollen germination rate will also decrease. Therefore, it is necessary to use a thermometer to keep abreast of temperature changes when drying pollen. After the pollen is baked, it is concentrated in a small bottle and set aside. The life span of pollen is not long. Under the condition of 50% humidity in greenhouse, the germination rate of pollen is 57.6% after 10 days and only 33.9% after 50 days. When the pollen is dry, the germination rate will decrease quickly. The amount of pollen needed for each flower is very small during pollination. in order to save pollen, fillers such as pine pollen, milk powder, lotus root powder and so on can be added to pear pollen before pollination. The dilution is 10 to 20 times the amount of pollen, be sure to stir well.

(3) the method of pollination can put the diluted pollen in a gauze bag, then tie it to the head of the pole and gently hit the pole with a stick to remove the pollen on the stigma of the flower. in this method, about 750 grams of pollen is needed in a pear orchard at full fruit stage. The pollen can also be mixed with 15% sucrose solution and sprayed on the stigma of the flower with a sprayer. It takes 1200-1500 grams of pollen per hectare of pear orchard in this way. You can also use the rubber head of a brush or pencil to dip in pollen to give flowers. Artificial pollination of pear flowers does not require pollination of every flower or inflorescence, just 1-2 flowers on a well-positioned, normal inflorescence. When pollinating, you only need to gently wipe the pollinator on the pollinated stigma, and scratch the stigma with excessive force, which will affect the normal progress of pollination and fertilization.

The complete solution for orchards with improper or insufficient pollination trees is high pollination varieties. It is necessary to carry out artificial pollination in order to meet the emergency, of course, the workload is relatively large. For simplicity, the flower branches of pollinated varieties can be cut off, placed in a bottle of water and hung on the upper part of the pear tree that needs pollination. A big tree needs to hang 4 or 5 bottles. This method is simple, but the effect is not as good as that mentioned above. In addition to the above-mentioned methods, bees can also be pollinated. It is suitable for pear orchards where pollination trees account for more than 20% of the whole orchard and the configuration is more uniform. It is more appropriate to put the beehive in the garden 2-3 days before flowering and 3 boxes in 2 hectares.

3. The nutrients needed for flowering and young fruit development come from the nutrients stored in the tree in the first year. If the number of flowers is large and the fruit setting rate is high, the stored nutrients will be exhausted quickly, and it will be difficult for young fruits to fully expand into commercial fruits and weaken the tree. Therefore, flower thinning and fruit thinning should be carried out for adult fruiting trees and trees with weak growth.

(1) Flower thinning begins with winter pruning. Too many flower buds can be removed when pruning in winter. If you still feel more flowers before flowering, you can remove the flower buds from the flower buds and retain the leaf buds to increase the number of leaves. This is good for restoring the tree.

In order to expand the crown, the flower buds of the axillary flower buds on the extended heads of the main branches and lateral branches should be all thinned, and the short fruit branches on the 3-4-year-old branches are generally about 10 cm, so that the fruits are evenly distributed, close to the main branches and trunk, and bear three-dimensional fruit.

(2) the purpose of fruit thinning is to ensure that the remaining fruit on the tree can get sufficient nutrients to grow into commercial fruit. So the sooner the fruit is thinned, the better. It can start in 2 weeks after falling flowers. The second fruit thinning was carried out 25-30 days after anthesis. When thinning fruit, first remove the fruit and deformed fruit caused by diseases and insect pests. The same variety should keep young fruits with longer fruit shape, long and thick stalks and glossy fruit surface.

The number of remaining fruits varies with variety and fruit size. The number of remaining fruits is determined according to the planned yield and fruit size. For example, a medium-sized Huanghua pear with a planned yield of 45000 kg per hectare and a single fruit weighing more than 250g is required to leave 180000 fruits, plus 10% insurance, resulting in a total of 198000 fruits. When considering the number of fruits left, we should take into account the sufficient number of leaves. In general, about 30 leaves supply a fruit nutrition, that is, about 1000 square centimeters of leaf area is needed to ensure the growth and development of a fruit. Among them, it varies with different varieties. Some late-maturing varieties (large fruit type) need more than 40 leaves to meet the nutrition of a fruit.

The method of thinning fruit. Usually look at the tree to leave fruit. There are more strong trees and strong branches, and vice versa. Leave more at the top of the crown and more at the small branches. The general principle is to keep the weak and the strong, the small and the big, the density and the sides. Usually leave 1 fruit or 2 fruits every 18m ~ 26cm. For varieties that are not easy to form flowers, it is necessary to consider the method of keeping fruit between buds to ensure stable yield.