LaMotte TRACE ELEMENT PLANT TISSUE TESTS PT-04 - Manual (Page 2)

IN TRO DUC TION
Tissue testing is based on the knowledge that, for most nutrients, the first
indication of a deficiency 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 filter paper.
For best results, we recommend analysis of material from plants displaying
deficiency or toxicity symptoms and from healthy plants not showing
these effects. In most cases, the nutrient disappears first 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.
COL LEC TION OF PLANT SAP
In these test procedures, sap is expressed from freshly cut plant tissue onto
a strip of filter paper. The chemical tests are then carried out by adding
reagents to the filter 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 filter paper (0471) in half and place the small plastic
bag within the fold.
3. Slip the filter 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 flat object until spots of sap
appear on the filter 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.