Thinning can weaken the growth of the parent branch (that is, the branch that undertakes thinning), but it can enhance the growth of the branch below the cut. The range of reinforcement is wider than that of short section, but the strength of reinforcement is not as large as that of short section. Therefore, thinning is less than short-cut long branches, more short-medium branches, sparse crown branches and good ventilation and light transmission. Thinning sometimes weakens and sometimes promotes the growth of branches above the incision. Whether it is weakened or strengthened depends on the growth strength, angle and the size of the incision. If the pruned branches are thin or the angle is small, and the branches above the incision are strong, thinning the weak branches will promote the branches above the incision, at least it will not be obviously weakened. On the other hand, when the angle of the thinned branches is large, they are robust, and at the same time, the branches above the cut are not robust. After thinning, the upper part of the incision is obviously weakened.
The overall reaction of pear trees after thinning is often related to the thinning position. When the apical dominance effect is greater than the thinning effect, the growth of branches above the thinning position can be enhanced, and vice versa. For trees with high middle trunk, large growth and strong growth potential, when the auxiliary branches on the middle trunk or the branches under the scissors of the top extension branches are drained, although the growth of the middle trunk can be weakened, the growth of the extension branches can be enhanced; For the main branches with large angles, thinning the branches at the front end often weakens the growth of extended branches.
When the pruning amount of thinning and short cutting is the same, thinning is more conducive to promoting the formation of flower buds than short cutting. While thinning some long branches, gently cutting and slowly releasing other medium and long branches can promote flowers more obviously. Because thinning can effectively increase the accumulation of nutrients in the early stage, improve the ventilation and light transmission conditions in the crown, which is conducive to the formation of flower buds and the improvement of fruit quality.
In the shaping and pruning of pear trees, thinning technology is often used in the following situations. First, in order to promote the growth of local branches, one or several branches can be thinned on the upper part of the branches; In order to weaken the growth of local branches, one or several branches can be thinned at the lower part of the branches. Secondly, in order to promote the germination of cryptoshoots or make thin and short branches flourish, pruning techniques can be used to inhibit the former and promote the latter, and the front ends of branches can be thinned appropriately. Third, in order to balance the growth of bearing branches before and after and prevent the previous loss, we can thin branches in front of branches to promote the growth of branches behind. Fourthly, in order to promote the formation of flower buds, increase the accumulation of nutrients and improve the ventilation and light transmission conditions in the crown, the branches can be properly thinned, too dense and weak, or too vigorous and too dense.