tissue

Tissue analysis provides a historical representation of the nutrient content of media 1-2 weeks prior to the time of tissue sampling.  Media samples should be taken in conjunction with tissue from normal and abnormal plants to provide enough information so corrective measures can be suggested.

nutrient content in the tissue

Influence of media pH:  Media pH will influence nutrient levels in the tissue.  In general, high media pH will inhibit uptake of iron, manganese, boron, etc and encourage greater uptake of calcium, magnesium or molybdenum.  Low media pH can result in excess uptake of iron, manganese or boron and inhibit uptake of calcium, magnesium or molybdenum.

Nutrient imbalances:  The next thing to look for is nutrient imbalances (please see ‘Nutrient Antagonisms’ below).  For example, if the tissue has high calcium and low magnesium levels, the media could have sufficient magnesium.  The calcium level might be so high that it competes with and inhibits magnesium uptake by the plant.

nutrient	if deficient	if excessive
Nitrogen, Potassium	Increase fertilizer rate.  Use a complete fertilizer high in the particular element.	Decrease fertilizer rate.  Use a complete fertilizer low in the particular element.
Phosphorus	Use a complete fertilizer with phosphorus.	Use a fertilizer with lower phosphorus and if used, check phosphoric acid rates.  Excess phosphorus can cause stretching in plants
Calciumab	Use complete fertilizers containing calcium: 13-2-13, 14-0-14, 15-0-15, 15-5-15, etc.	Avoid calcium fertilizers and maintain sufficient magnesium levels in the media.
Magnesiumab	Use complete fertilizers containing magnesium: 13-2-13, 14-0-14, 15-5-15, etc.  OR epsom salts (magnesium sulfate).	Avoid magnesium fertilizers and maintain sufficient calcium levels in the media.
Sulfurab	Use complete fertilizers containing sulfur   OR epsom salts (magnesium sulfate).	Avoid sulfur fertilizers and if used, check sulfuric acid rates.
Sodium, Chlorideb	n/a	Can occur when fertilizer salts are low or when media is leached insufficiently. Maintain normal fertilization rates and analyze media.
a Test your water to determine the level of calcium, magnesium and sulfate.  Some water sources might not have sufficient quantities of one or more of these elements. b Your water might contain excessive levels of the particular nutrient.  If so, excessive accumulation of this nutrient in the media can be minimized by allowing 15-20% of the applied water or fertilizer solution to run out the bottom of the container.

nutrient antagonisms

Excesses of certain nutrients in the media might lead to low levels of other nutrients in the tissue.