simple, because the quality of the oily nuts
is determined by how well the kernels are filled. All but one of our
most important nuts--almonds, filberts, hickory nuts, pecans, and
walnuts--are oily nuts; and well filled kernels contain from 50 to 75
percent or more of oil, depending upon the species. Chestnuts are
starchy nuts and contain less than one percent of oil. The relationship
between the degree of filling and the composition of the kernel in oily
nuts is outstanding, in that the better filled nuts have a higher
content of oil and a lower content of protein, carbohydrates, water, and
undetermined constituents than do poorly filled nuts. Highest quality of
the kernels is directly associated with highest oil content and highest
degree of filling. Nut kernels that are poorly filled are often hollow,
shrunken, shriveled, and chaffy. When eaten they may taste sweet, but
are lacking in the oily flavor characteristic of the particular species
of nut eaten. It is only in the best filled nuts that highest quality,
flavor, and oil content are found.

The degree to which nuts are filled or how well the kernels are
developed at harvest is determined by a rather large number of
interrelated factors: (1) Size of crop, or ratio of number of leaves per
nut; (2) average size of nuts; (3) condition of leaves; (4) amount of
second growth of the trees; (5) size of preceding crop and how well the
nuts produced were filled; (6) disease and insect injury to the nuts;
(7) weather conditions; (8) heterosis or effect of cross-pollination on
embryo size.

+Size of crop:+ Nut growers want their trees to bear large annual crops of
nuts. It is very seldom that one hears a nut grower express the opinion
that a certain tree is carrying too many nuts for the crop to attain
proper size and fill well, yet this is very often the case. Furthermore,
the production of a large crop of poorly filled nuts one year is almost
certain to result in a light crop or none at all the following year.
There is a very close inverse relation between the size of the crop
produced and the degree to which the nuts are filled at harvest, namely,
the larger the crop the less the nuts will be filled. It has been
pointed out above that nuts are storage organs, and the food materials
required to grow and fill them must be made in the leaves. When too many
nuts are set and carried through to the filling period, in proportion to
the number of leaves or the leaf area of the