Measures for sulfur Flower and Fruit thinning of Walnut

   flower and fruit thinning is the main technical measure to improve the yield and quality of walnut trees. It can save a lot of nutrients and water, which is not only conducive to the development of trees in the same year, improve the yield and quality of nuts in the same year, but also conducive to shoot growth, flower bud differentiation, and ensure the yield of the following year.

   1. The reason of flower and fruit thinning for walnut trees with too many female flowers, proper sulfur flowers and fruit thinning should be carried out to control the number of flowers and fruits, which can reduce the ineffective consumption of nutrients, increase effective flowers, increase fruit setting rate, coordinate the contradiction between reproductive growth and vegetative growth, and have sufficient nutrients to supply tree growth and flower bud differentiation, so that fruit, tree growth and flower formation can be achieved. In addition, early fruiting walnut trees are mainly lateral flower buds, with a large number of female flowers. in order to ensure the relative balance of vegetative growth and reproductive growth, high quality, high yield and stable yield, flower and fruit thinning must be carried out after full fruiting period. otherwise, the fruit will become smaller and the quality will become worse because of too much fruit. in serious cases, it will lead to premature weakening of the tree, drying up of a large number of branches and even death of the whole plant.

   2. The principle of flower thinning and fruit thinning in walnut, the key is to keep the right amount of flowers and fruit. Because under certain conditions, the yield is positively related to the retention of fruit, so the amount of flowers and fruit must be just right. If there are too many fruits left, the fruit is small, the fruit is light, the quality is poor, the increase of fruit does not increase production, let alone add value, and there are too few fruits left, then the fruit is large, the single fruit is heavy, but the number is too small, and the yield can not be increased. The amount of fruit retained in walnut is generally determined according to the number of compound leaves or the thickness of fruit branches. Generally speaking, fruiting branches with two fruits need to have more than 5 or 6 normal compound leaves in order to ensure the normal development of branches and fruits. Fruit branches with 1 or 2 compound leaves are difficult to form flower buds, and even if they bear fruit, the fruit is underdeveloped, and the fruit on this fruit branch should be removed. Walnut is the fruit of strong branches and strong branches. when the thickness is more than 1.0 cm, it can generally set 2 or 3 fruits; when the thickness is 0.8 cm or 1. 0 cm, it can set 1 or 2 fruits; the thickness is 0. 5%. Fruit branches less than 7 cm can hardly hold fruit.

When    is thinning flowers and fruits, it should determine the yield according to the number of branches, keep flowers according to quantity, more flowers, less flowers or not; weak trees and weak branches are more sparse, strong trees and strong branches are less sparse; prosperous trees with few flower buds are not sparse, so as to adjust the tree potential and stabilize the yield. Generally speaking, the number of fruits per square meter of tree crown projection area is 60 ~ 80 per square meter under moderate site conditions and medium tree potential, and 80,100 fruits per square meter of walnut trees with superior site conditions and strong tree potential.

   flower thinning and fruit thinning depends on the land, the garden, and the tree. Don't copy it mechanically and don't go too far. In areas with frost damage and orchards with serious diseases and insect pests, the amount of flowers and fruits left should be 30% to 40% more than the actual amount, and fruit thinning should be carried out after the fruit is stabilized, so as to make up for the losses caused by frost injury or diseases and insect pests.

   3. The time of flower thinning and fruit thinning of walnut should not be late. Too late not only increases the ineffective consumption of nutrients in the early stage, but also affects the fruit development, which can not play its due role. When thinning fruit, it can be done after physiological fruit drop, usually 20-30 days after fertilization of female flowers, that is, when the ovary develops to 1 cm in diameter. 5 cm is appropriate.

   4. The method of thinning flowers and fruits

   (1) artificial thinning method should pay special attention to that fruit thinning is limited to early-bearing walnut varieties with high fruit setting rate, especially those with weak trees and many fruit-bearing trees. First, the young fruit on the weak tree or thin branch can be removed, and it can also be cut off together with the weak branch. when each inflorescence has more than 3 young fruits, 2-3 can be retained depending on the strength of the fruiting branches. the remaining fruit parts should be evenly distributed in the crown, and the inner chamber of the closed canopy can be more sparse.

   (2) the effect of artificial flower and fruit thinning by chemical thinning is stable, but it is labor-consuming and time-consuming, while chemical flower and fruit thinning saves labor and labor, but chemicals and methods suitable for local application should be selected, and small-area experiments should be carried out before large-scale application. The medicament and concentration suitable for flower and fruit thinning of walnut need to be further studied.