LaMotte AM-41 Hydroponics Test Kit - Manual (Page 11)

PLANT TIS SUE TESTING
As a supplement to the nutrient solution tests provided in this kit,
additional tests can be conducted on fresh plant tissue, or an extract of the
fresh plant tissue. These tests frequently allow verification of suspected
nutrient deficiency or other abnormalities.
Fresh plant material should be obtained from the growing plants, both
normal and questionable plants. It is important to test healthy plants at the
same time that the tests are made on questionable plants, as the greatest
value may be derived from the tests when they are used in a comparative
manner. If plant parts are to be used, select small lots of leaf petioles, or
succulent portions of the stem, in the plant part most affected by any
observable symptom. Using a clean, sharp knife or razor blade, cut the
material into fine bits of not more than to inch in length and thickness.
Use equal weights of plant material from health and unhealthy plants. A
weighed sample is necessary because there is variation in the size of plant
material used in the tissue analysis.
Algae cells may also be used for tissue analysis. Equal amounts of algae are
filtered or centrifuged from the nutrient solution. The cells are ground up
by the use of a glass homogenizer, weighed and put in the extraction tube.
1.
Fill two test tubes (0608) to the 5 mL line with the weighed plant
tissue.
2. Dilute to 20 mL with Deionized Water (5115PT). Cap and shake
vigorously for 5 minutes.
3. Use the funnels (0459) and filter paper (0465) filter the tissue extract
into clean test tubes (0608).
NOTE:
If excess turbidity or color is found in the extract add 3 drops
of Charcoal Suspension (5638) to the extraction tube. Shake for 1
minute and refilter.
5. Test filtrate following the same procedure used to test a nutrient
solution for a particular nutrient. The tissue extract is substituted by
volume for the nutrient solution or an appropriate dilution of the
nutrient solution.
DISCUSSION OF RESULTS: The results should be interpreted on a
comparative basis. No definite values can be assigned for general
application, since the magnitude of the results obtained on different species
and under different growing conditions may vary significantly.
Interpretations should be based on comparisons of the same species and
age, and grown under the same general cultural conditions.
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