Effects of Light Quality on Root Elongation and Nodulation of Zamia floridana DC. Seedlings in Sterile Culture

Abstract

The effects of broad spectrum red, green and blue light as well as narrow spectrum green and blue light on primary and secondary root elongation and secondary root nodulation of Zamia floridana DC. seedlings were examined in sterile culture. Seedlings were grown at 27 ± 2 °C in agar slants of modified White's minerals plus 2% sucrose, pH 5.7. Roots were exposed to darkness or to 12 h photoperiods. Red light inhibited primary and secondary root elongation but it did not induce nodulation. Both broad and narrow spectrum blue and green light induced nodulation and inhibited primary and secondary root elongation. Both of these latter light qualities were more inhibitory than red light, and blue light was more inhibitory than green light. Blue light was also more effective than green light at inducing nodulation. Root photomorphogenesis of Z. floridana appears to be principally regulated by blue light.