an
unnamed variety carried under the accession number 7916. The last
variety is characterized by dwarf, heavy-bearing trees that mature their
crops very early in the fall, whereas Meiling and Nanking are vigorous,
fast-growing varieties that mature their nuts in midseason. In the early
spring of 1948 thirty-six two-year-old grafted trees were planted 25
feet apart in the orchard in four short rows of nine trees each. The
three treatments consisted of (1) no pruning; (2) pruning to a 2-foot
head; and (3) pruning to a 4-foot head. Three trees, one of each
variety, were included in a plot or treatment. Thus, the experiment was
arranged in a randomized block design with the three treatments
randomized in each row and the four rows serving as replications. Each
spring the trees received a liberal application of a 10-6-5 fertilizer.
Strips six to eight feet wide on each side of the contoured rows
received frequent cultivation each growing season, while strips of
orchard grass sod were left between the rows to prevent erosion. The
soil is Riverdale (tentative series) sandy loam that had been in orchard
grass sod for ten years before the experiment was begun. It has been
necessary to spray the trees each year with DDT, parathion, or both to
control Japanese beetles and mites.

Pruning of the trees was begun during the first winter following the
planting in the orchard, but only a few of the lower limbs were removed
in order not to dwarf the pruned trees severely. The second winter a few
more lower limbs were removed and at this time the two-foot-head
treatments were complete. A third pruning was necessary before the heads
of the trees in treatment three could be raised to four feet. Detailed
records and measurements were made of the diameter of each tree trunk
one foot above the ground, and of the weight and number of nuts produced
(yield).

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=

===========+=============================+==============================+
| | |
| Average diameter of tree | |
| trunk (millimeters) | Yield of nuts (pounds) |
Treatment +-----------------------------+------