Effect of Excessive Calcium Applications on Growth and Postharvest Performance of Bedding-plant Impatiens

ABSTRACT

Application of excessive amounts of calcium (Ca) during the production cycle improves the quality and postharvest life of several florist crops. Most bedding plants are fertigated with Ca at 100 to 200 mg L^{− 1}throughout the production cycle, but we do not know the effects of higher Ca concentrations. The objective was to evaluate the effect of application of excessive Ca (≥ 280 mg L⁻¹) supplied during the production cycle on the growth, development, and subsequent postharvest performance of bedding-plant impatiens (Impatiens wallerana Hook. f. ‘Super Elfin White’) under simulated retail conditions. Calcium was applied at 120, 200, 280, 360, and 440 mg L⁻¹ during each fertigation during the growing cycle. The total nitrogen (N) concentration was 150 mg L⁻¹, and the nitrate (NO₃ ⁻)-N to ammonium (NH₄ ⁺)-N ratio was 1:1. Application of excessive Ca began 30 d after sowing (22 d after germination) and continued until 60 d after sowing. From day 60 to day 65 only deionized water, as a leach, was applied. From day 65 to day 90, plants were held under shade cloth and irrigated with tap water. Excessive Ca applied during the production cycle decreased shoot dry weight, shoot fresh weight, leaf number, and shoot tissue K concentration at the end of the production cycle. Excessive Ca applied during the production cycle also decreased shoot dry weight, leaf number, and shoot tissue potassium (K) concentration at the end of the postharvest period. Plant height, plant diameter, number of open flowers, and number of unopened flower buds at the end of the production cycle and at the end of the postharvest period were not affected by the amount of Ca applied during the production cycle. It was concluded that excessive Ca applied to bedding-plant impatiens during the production cycle did not benefit plant performance during either the production cycle or the postharvest period.

Keywords:

• Potassium
• magnesium
• dry weight
• fertigation
• Impatiens wallerana

ACKNOWLEDGMENTS

This is a journal paper of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, and this research has been supported by Hatch Act and State of Iowa funds. We thank the Fulbright program of Guatemala and the Institute of International Education for financial support of FRR.

Notes

^zEach treatment mean represents two experiments run independently each with four replicates.

^yValues obtained with a chlorophyll meter model SPAD-502.

^xDue to a lack of points, it was not possible to fit combined models such as linear plus plateau.

^NSNonsignificant at P > 0.05; P value stated otherwise.

^S.E.M.Standard error of the mean.

^zEach treatment mean represents two experiments run independently each with four replicates.

^ySamples from the end of the production cycle were taken after 30 d of treatment application plus 5 d of irrigation with deionized water.

^xPostharvest samples were taken after plants had been in the postharvest environment for 25 d.

^wDue to a lack of points, it was not possible to fit combined models such as linear plus plateau.

^NSNonsignificant at P > 0.05; P value stated otherwise.

^S.E.M.Standard error of the mean.