Studies of Calcium and Magnesium Usage by Subirrigated Pot Chrysanthemums
Excessive fertilizer use in greenhouse floricultural operations results in low nutrient use efficiency by plants. Here, I tested the hypothesis that calcium and magnesium use efficiencies of subirrigated pot chrysanthemums can be improved by combining moderate levels of the respective macronutrient during vegetative growth with the removal of the entire suite of nutrients at bud break, without adversely affecting plant/flower quality. Two experiments were conducted for each macronutrient in a naturally-lit research greenhouse using a split-plot design with nutrient treatment (1.68-6.75 mmol L-1 calcium or 0.38-1.5 mmol L-1 magnesium) as the main plot and cultivar as the sub-plot, and the main plots were arranged as a randomized complete block design of four blocks. Macronutrient composition of the diagnostic leaf and quality/development of the plant/inflorescence were largely unaffected by macronutrient treatments, suggesting that use efficiency improved by approximately four-fold. This modified delivery practice could contribute to low-input production of floricultural crop.