Mineral Nutrition Status of Valencia Orange


suited in the highest Brix/acid ratio at that range. These data
are in general agreement with results reported by Reuther and
Smith (16) and Sites and Deszyck (22).
 Leaf, Fruit and Soil Composition.-The quantity of nitrogen,
phosphorus and potassium added in the fertilizer was usually
reflected in one or more components studied. The results are
presented in Table 17. Applications of magnesium in the water-
soluble form were not reflected in the magnesium contents of
leaves, fruits or soil. The nitrogen content in leaves was re-
lated to the quantity of nitrogen in the fertilizer, particularly
more apparent in the lower ranges of applied nitrogen. No sig-
nificant relation was found between the nitrogen content of fruit
and the rate of nitrogen application.
 The rate of phosphorus used in the fertilizer, on the other
hand, was reflected in the phosphorus content of fruit and in
the available phosphorus content of soil but not of leaves. A
relationship was observed between phosphorus applications and
soil acidity. A similar relation also existed between the avail-
able phosphorus content of soil and the pH (not shown in Table
17). It had also been observed in controlled experiments by
Smith (24).
 The data were too erratic to prove any correlation between
the rate of potassium applied and the potassium content of leaves
or fruit. Other factors may have confounded the results due to
potassium so that its significance was not revealed. In order
to find out if the nitrogen applied in the fertilizer had any effect
on potassium, multiple regressions were calculated for the po-
tassium contents of leaf and fruit. The amounts of nitrogen
(X1) and potassium (X2) in the fertilizer were used as inde-
pendent variates on which the potassium content of leaf (Y1)
and fruit (Y2) were dependent. Highly significant correlation
coefficients were found. The regression equation for leaf po-
tassium content (Yi = 1.838-0.125X, + 0.137X2) indicated that
the average leaf-potassium content expressed in percent of dry
weight decreased 0.125 with each pound of nitrogen applied to
the tree, but increased 0.137 with each pound of potassium ap-
plied. The influence of nitrogen on the potassium content of
fruit was about one-half that of the potassium applied (-., =
1.247-0.033X +- 0.070X,). In simple analysis when only one
element is considered, interrelation with another element cannot
be identified. It is possible that a grove fertilized with a large
quantity of potassium may also receive nitrogen at a high rate.