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Argo and Fisher pore over the details to systematically identify and correct common nutritional problems found in the greenhouse.
MOST nutrients are actively taken up by the plant from the soil solution. With active uptake, the plant roots use energy to scavenge the root environment for soluble nutrients. For nutrients that are taken up actively (like nitrogen or phosphorus), their concentration in the root medium (as measured with soil tests) tends to correlate well to uptake by the plant.
The exceptions to this rule are calcium and boron. Calcium and boron are taken up passively by the plant. With passive uptake, nutrients only move into the plant along with the water used for transpiration. No transpiration, no uptake, regardless of the concentration of those nutrients in the soil solution.
The environment where the plants are being grown will directly affect transpiration rates, and calcium and boron uptake. The types of environments that suppress transpiration can include:
* Hot, humid conditions, especially when light levels have been reduced with excess shade.
* Cool, humid conditions, especially when no de-humidification is occurring.
* Greenhouses with little or no air movement, especially when conditions are humid.
Other management factors can also reduce transpiration rates and affect calcium and boron uptake. For example, a high salt level (high EC) in the root media will reduce transpiration by making it harder t'oi the plant to take up water out of the soil solution. Constant overwatering or underwatering may also reduce transpiration rates.
What Else Affects Calcium & Boron Uptake?
Don't forget to check roots. Calcium and boron are only taken up by the plant at the root tip. Root tip damage caused by salt burn, overwatering, fungus gnats or root pathogens such as Pythium can cause calcium or boron deficiency symptoms similar to those caused by environmental conditions. In that case, careful irrigation...