Experimental Results
Table 1. Effects of training to different heights of head on the average diameter of tree trunk and yield of nuts of three varieties of Chinese chestnuts at the end of the third season (1950) after transplanting
| Treatment | Average diameter of tree trunk (millimeters) | Yield of nuts (pounds) | Number of nuts | |||||||||
| Meiling | No. 7916 | Nanking | Tree average | Meiling | No. 7916 | Nanking | Tree average | Meiling | No. 7916 | Nanking | Tree average | |
| No pruning | 43 | 43* | 47 | 45 | .19 | .43* | .05 | .16 | 11 | 22* | 2 | 10 |
| 2-foot heads | 25 | 19 | 21 | 22 | 0 | .12 | 0 | .04 | 0 | 7 | 0 | 2 |
| 4-foot heads | 27 | 22 | 25 | 25 | 0 | .03 | 0 | .01 | 1 | 4 | 0 | 2 |
[*] 2 trees missing.
Data on the diameters of the tree trunks and yields of nuts at the end of the third year in the orchard are given in table 1. It should be pointed out first that these grafted trees produced some nuts the third growing season they were in the orchard. This is very much earlier than seedling trees ordinarily could be expected to bear nuts. It will be noted that trees of Number 7916 developed a somewhat smaller trunk on the average than the other varieties did, but Number 7916 outyielded them about two to one, both in weight and in number of nuts produced. The tendency of Number 7916 to bear nuts earlier and on smaller trees than other varieties may prove to be a valuable characteristic that will justify naming and releasing this clone as a new variety. The fact that it matures its nuts early may also make it suitable for growing in more northerly areas than other varieties, because the length of season required for maturing the crop presumably is shorter than for other varieties. However, this cannot be determined without extensive tests in the North, which are now being made by a number of growers.
It will be noted also in table 1 that the trunk diameters of the unpruned trees were about twice as great as were those of trees trained to two-and four-foot heads; and furthermore, the yield of nuts was more than four times as great. This means that cutting off the limbs that formed below the 2-foot level checked growth so that the bearing surface of the tops was greatly reduced as compared with that of unpruned trees. Also, growth of the tops of these trees was etiolated and spindly, and the shoots produced few or no catkins as compared with the abundant catkins produced by the unpruned trees. Several of the trees with four-foot heads became so top-heavy that staking was necessary, and nearly all the pruned trees leaned to some extent. At the end of the third year in the orchard, the unpruned trees were much taller than trees headed at two and four feet, and the spread of branches was also much greater. Preliminary results from this experiment indicate that early pruning of young Chinese chestnut trees causes severe dwarfing and consequent delay in the formation of catkins and the bearing of nuts. All pruning operations should, therefore, be delayed until the trees reach bearing age, and from that time on low limbs may be removed gradually from year to year until the trees are trained to the proper height.
Literature Cited
(1) Crane, H. L.
The effect of height of head on young apple tree growth and yield
West Virginia Agr. Exp. Sta. Bul. 214. 1928
(2) Tufts, Warren P.
Pruning young deciduous fruit trees
California Agr. Exp. Sta. Bull. 313: 111-153. 1919
Discussion
MR. McDANIEL: What age and height were these trees when planted?