478 Preharvest Calcium Application and Its Benefit on Vase Life of Lupinus havardii Watts Cut Flowers

Abstract

Lupinus havardii has gained popularity as a potentially new and unique cut flower species, but its compound, ethylene-sensitive inflorescences (racemes) undergo rapid senescence and deterioration on cutting. The purpose of this study was to evaluate the influence of Ca culture solution applications on L. havardii cut-flower longevity. Four supplemental Ca treatments were incorporated into the nutrient solution (0, 2.5, 5.0, and 10.0 mM Ca using CaCl2), with four replications in a randomized complete-block design. Raceme Ca concentration increased with increasing Ca application, ranging from a low 5300 mg·kg-1 dry weight (0 mM supplemental Ca) to a high of 7500 mg·kg-1 (10.0 mM supplemental Ca). Calcium application deferred the daily loss in raceme fresh weight (FW) for up to 10 days of vase life in a concentration-dependent manner (P < 0.01), with the effect most pronounced between 5 and 9 days following cutting (average FW of 72% and 83% of day zero values for the control and 10.0 mM Ca, respectively, with 2.5 and 5.0 mM treatments intermediate). The cut racemes of L. havardii are model organs for spatially and sequentially organized postharvest development, with continued, 6-day postcutting life including 4-fold increases in cell permeability of basal, most mature flowers, marginal but significant increases in cell permeability of the most recently expanded flowers, and a 50% increase in total flowers number resulting from inflorescence expansion. Preliminary data indicate that manipulation of Ca nutrition may be a viable, inexpensive, and environmentally safe alternative to silver-based compounds currently in use for the vase life extension of L. havardii inflorescences.