Potassium deficiency of greenhouse cucumbers may be
initially observed as chlorosis (yellowing) of the older lower
leaf margins. As symptoms progress, interveinal chlorosis and
firing (necrosis) of the leaf margin and interveinal regions will
develop while the leaf midrib and veins remain green.
Managing pH and mineral nutrient concentration in hydroponic
solutions is important for maintaining healthy crops and
maximizing yield. Routine sampling and analysis of the nutrient
solution should be performed to check pH, electrical
conductivity, alkalinity, and mineral nutrient concentrations. In
addition, leaf tissue sampling and analysis should be
performed to determine mineral nutrient concentrations and if
any adjustments to the nutrient solution are warranted. When
routine sampling and analyses are not performed, nutrient
disorders may develop due to pH drift or an imbalance of
nutrient uptake relationships.
To correct potassium deficiency, growers may
consider adjusting the nutrient solution or spray foliar applications of 2% potassium sulfate.
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