Common Tissue Test Questions

Tissue testing season also brings questions about interpreting tissue test results. Here are five of the most common questions and answers.

“What yield goal is used for the sufficiency ranges on the report?”

In tissue analysis, there are “sufficiency” ranges and “target/optimal” ranges. Our sufficiency ranges are levels that should not result in a physiological deficiency; therefore, yield does not impact sufficiency values. Yield goals could impact target or optimal ranges, but that concept has yet to be fully vetted by the industry.

“I see visual deficiency symptoms, but everything is sufficient?”

Sometimes weather conditions can create situations that limit a plant’s ability to metabolize nutrients or process their effects. The best example is purple corn during the first few weeks of growth in a period of cool, wet weather. The corn is unable to utilize all of the photosynthates being produced during the day, leading to a buildup of the purple pigment anthocyanin. This is the same reaction plants have when they are phosphorus deficient and cannot transport photosynthates efficiently.

Secondly, don’t just look at the graphs on the report; look at the actual data. If the value for a given nutrient is at the very bottom of the sufficiency range, external or compounding factors could cause a visual deficiency to appear. Likewise favorable weather conditions or compounding factors can cover up visual deficiency symptoms. For examples excess nitrogen can reduce the visual appearance of sulfur deficiency.

“Why is my aluminum level so high? Do I have aluminum toxicity?”

This is a common question for very young plant samples, especially whole-plant samples. In most cases, this is the result of soil contamination, which is often paired with very high iron levels. True aluminum toxicity will kill plant roots before the plant is able to hyperaccumulate aluminum.

“Does ALGL wash tissue samples before analysis?”

While some labs wash tissue samples to remove contaminants, others do not, and both approaches have valid reasons behind them.

At ALGL, we do not wash plant tissue samples. If plant tissue is washed after the sample begins to wilt, potassium can be lost from the sample. Delaying washing until the sample arrives at the lab has limited success in removing foliar spray residues from plant tissue. We believe it is best to wash or rinse samples with de-ionized water at the time of collection if contamination is a concern.

“I took a sample of plants in really bad shape (AKA dead), and the results show multiple deficiencies and excessive levels. Which deficiency and/or excess should I focus on first?”

A wide range of physical processes that occur at plant death can confound deficiency data. Plants can lose a significant amount of biomass as they die and begin to decompose. This can lead to increased concentrations of structural and/or immobile nutrients. In addition, cell rupture can result in the loss of non-structural and mobile nutrients, decreasing their concentrations.

Dead plants tell no tales. Collect samples from the border of the affected area to capture usable tissue data.

If you have additional questions, please reach out to your ALGL regional sales agronomist.