Effects of different branch bending angles, notching, and pinching on the characteristics of ‘Wen 185’ walnut branches

Abstract: 【Objective】The effects of bending, notching and pinching the 1 year-old branches at differ- ent angles in‘Wen185’walnut variety on branch growth and development were studied, in order to provide reference for the rational distribution of bearing branches of the precocious walnut【. Methods】The 1 year-old branches of‘Wen 185’walnut variety were bended to three angles (60°, 90° and 120°). At the same time, in each bending angle group, there were treatments of branch bending, branch bending plus notching, and branch bending plus pinching. The effects of different treatments on the growth and development characteristics of the 1 year-old branch were investigated.【Results】The angle of branch bending significantly affected the characteristics of branches. The branching ability reached 67.72% un- der the branch bending angle of 90°, which was significantly higher than that in CK1, but there was no significant difference between 60° and 120° bending treatments and CK1. The average length and diame- ter of new shoots decreased gradually with the increase of branch bending angle. Among them, the length and diameter of new shoots under 120° treatment were significantly lower than those in CK1. There was no significant effect on the number of female flower buds in the new shoots under different  bending treatments. However, the number of male flower buds in 90° and 120° branch bending treat- ments was significantly higher than in CK1 and the 60° treatment. The first internode had the shortest length in the new shoots in all treatments, but fruit set was the highest, reaching 41.04%-47.50%, which was 43.65%-66.26% higher compared with CK1. Branch bending and notching had significant influence on the branching ability of buds. Among them, the branching ability reached 74.54% and 73.33% under 90° and 120° bending plus notching treatments, respectively, and was 17.96% and 16.05% higher com- pared with that of CK2, respectively. Notching did not significantly affect the average length of new shoots under different bending angles. The number of female flower buds and fruit set in the new shoots were the highest under 90° bending plus notching treatment, where the average number of female flow- er buds in each new shoot was 2.49, significantly higher than in the other treatments, and the average fruit set was 68.18%, significantly higher than that in CK2. There was no significant effect on the length of the first internode among bending and notching treatments. The branching ability was 69.97% under branch bending at 90° plus pinching treatment, which was significantly higher than that in the other angles with pinching. With pinching treatment, the length and diameter of the new shoots decreased with the increase in branch bending angle. Among them, the branches with 90° and 120° bending angles were the shortest in length and diameter. The length of the first internode of the new shoot under 90° branch bending plus pinching treatment was the shortest (23.10 cm) and significantly lower than in the other treatments. Pinching had no significant effect on the number of female flower buds the fruit set in the new shoots increased by 41.03%-90.46%【. Conclusion】The growth characteristics of new shoots in‘Wen185’walnut variety were significantly affected by branch bending, notching and pinching treat- ments. The branching ability and fruit set in the new shoots were significantly improved under 90° branch bending plus notching treatment. Branch bending and notching could evidently reduce the length and diameter of new shoots, increase the amount of shoots in the middle and lower parts of the branches, regulate the numbers of male and female flower buds, and balance the tree vigor.