Florida Agricultural Experiment Stations


illustrate the extent of parallel fluctuations between the mineral
compositions of leaf and fruit.
 There was no significant correlation between the nitrogen
contents of leaf and fruit. The potassium contents of leaf and
fruit were only weakly correlated, even though statistically sig-
nificant. This is probably due to the non-stability of potassium
level in the leaves. Phosphorus and calcium contents showed
about the same degree of correlation between leaf and fruit.
The magnesium contents of leaf and fruit were very closely
related. This was also indicated by their similarity in relation
to fruit quality.

 ROLES OF LEAF, FRUIT AND SOIL ANALYSES IN
 STUDYING THE MINERAL NUTRITION OF CITRUS
 Although leaf analysis has been extensively used by research
workers in studying the mineral nutrition of citrus, its applica-
tion in commercial groves has not been fully tested. One of the
objects of this survey was to explore the possibility of applying
leaf analysis under commercial conditions. Phosphorus is prob-
ably the only element of the five studied whose status cannot
be satisfactorily determined on the basis of leaf analysis. One
of the more useful functions of leaf analysis, which was not
included in the present study but should be followed up, is to
study the trends in the mineral nutrition of groves in relation
to their fertilizer programs and to predict the approach of any
deficiencies or excesses so that necessary corrections can be
made.
 Fruit analysis to study the mineral nutrition of citrus has
not been widely used. Results obtained from the survey indi-
cated that fruit analysis is a valuable tool that can be used to
supplement leaf analysis. Sampling error can be reduced greatly
when fruit analysis is employed. This can be very useful in
the latter part of the year when it is almost impossible to inter-
pret the data of leaf analysis due to inability to accurately de-
termine age of leaf. In general, the mineral composition of
fruit is more closely correlated to fruit quality than leaf analysis.
It was pointed out in earlier discussion that the phosphorus con-
tent of fruit is a more satisfactory index than leaf in studying
phosphorus nutrition of citrus. There is, at present, insufficient
data to set up standards for fruit analysis as has been done in
leaf analysis. With sufficient data accumulated similar standards
could also be set up for fruit. These standards will be especially
useful for fruit quality control studies.