Calla Lily Growth and Development Under Saline Irrigation

Salinity is a problem for crop production worldwide, which can affect not only the yield of ornamental plants, but also their quality. Calla lilies (Zantedeschia K. Koch) are a popular cut flower and landscape plant. In this study we examined how salinity applied either pre- or post-emergence altered shoot growth and flower production compared with standard growth conditions. Salinity applied post-emergence did not significantly affect shoot growth in either the 25- or 50-mM NaCl treatments; however, irrigation with a 50-mM NaCl solution did significantly reduce dry weight and flower production compared with the control. The most drastic effect on flower production was observed when the 50-mM treatment was applied pre-emergence. Although flowering time did not vary among treatments, in the spring, flowering success was less than 50% in the 50-mM treatment, which was significantly less than the other treatments. The plants in all treatments had good visual quality and high relative water content although the shoots of the salt-stressed plants had a Na+ content two to five times greater than the control. We hypothesize that the maintenance of visual quality may in part be the result of increased Ca2+ concentration (up to four times the amount in the control) in the shoots of the salt-stressed plants, which may have helped maintain turgor and cell membrane integrity under saline conditions. Our results indicate that use of irrigation water salinized by NaCl with an electrical conductivity (EC) more than twice as high as that recommended for optimal calla growth (1.5 dS.m(-1) compared with 3.4 dS.m(-1)) can be used without a loss in plant quality, thereby increasing irrigation options for calla lilies, particularly in areas where high-quality water is scarce.