LaMotte TRACE ELEMENT PLANT TISSUE KIT SAP SPOT TEST - Manual (Page 2)

INTRODUCTION
Tissue testing is based on the knowledge that, for most nutrients, the fi rst indication of
a defi ciency is the disappearance of the nutrient in a soluble form from the plant sap.
Therefore, chemical tests capable of detecting the presence or absence of a nutrient in
the sap can indicate the presence or absence of a nutritional stress within the plant.
This kit contains trace element tests for ferrous and ferric iron, boron, manganese,
copper, and zinc. These tests are essentially “spot tests” which are carried out on the
plant sap absorbed on fi lter paper.
For best results, we recommend analysis of material from plants displaying defi ciency
or toxicity symptoms and from healthy plants not showing these effects. In most cases,
the nutrient disappears fi rst from the oldest leaves then from the young leaves, and
last from the basal stalk of the plant. It may be advantageous to test both old and new
tissue, but generally a test should be made on the leaf sheaths or, with very young
plants, on the stalk. For small grains and alfalfa, the stems are used, while for beets,
beans, potato, tomato and geranium, the leaf petioles are used.
COLLECTION OF PLANT SAP
In these test procedures, sap is expressed from freshly cut plant tissue onto a strip of
fi lter paper. The chemical tests are then carried out by adding reagents to the fi lter
paper on which the sap has been absorbed. In the case of copper and boron, the tests
reagents are impregnated in the test paper strip. The sap is collected in the following
manner:
1. Place the plant tissue to be tested in a small, perforated, plastic bag (1196). This
will minimize contact of the green plant tissue with the paper to reduce staining of
the paper.
2. Fold a piece of fi lter paper (0471) in half and place the small plastic bag within
the fold.
3. Slip the fi lter paper/plastic bag into a large plastic bag (1196). This is done to
avoid contamination from the pliers.
4. Squeeze with the pliers or press with a fl at object until spots of sap appear on the
fi lter paper.
5. Complete the chemical tests.
NOTE: It is advisable to run a blank test to take into account any interferences
that may occur from the reagents. This is done by performng the tests on a drop of
deionized water at the same time the plant sap is being tested.