Effects of Using Vegetative Shoots of the Preceding Season on Bur Setting of Japanese Chestnut Trees

Abstract

The character of bur setting of the vegetative shoots of the preceding season were compared with that of the flower bearing shoots (containing female flower bearing shoots and only catkin bearing shoots) of the preceding season.
Four varieties, ‘Ginyose’, ‘Tsukuba’, ‘Ishizuchi’and‘Tanzawa’were used.
The thickness and the length of the new shoots sprouted on branches of the preceding season which the weak twigs were cut off at winter pruning were compared with those of the new shoots from the branches with the twigs left as they were.
Results as follows;
1) Bur setting of‘Ginyose’seemed unstable.
2) Young trees had more female flowers than old trees in all four varieties.
3) The number of female flowers had a higher correlation to the thickness rather than the length of the shoots of the preceding season.
4) A high correlation was seen between the number of female flowers and the yield of burs.
5) It was suggested that the use of vegetative shoots of the preceding season is useful in young trees for the varieties which the bearing of female flowers were good, but the trees should be kept fairly vigourous.
6) It was desired that the cuting off of the weak twigs should be kept to a minimum quantity.