Effects of solar UV radiation on germination of conchospores and morphogenesis of sporelings in Porphyra haitanensis (Rhodophyta)

Abstract

The eVects of ultraviolet radiation (UVR 280–400 nm) on the germination of Porphyra haitanensis conchospores and on the growth and morphogenesis of the subsequent sporelings were investigated by culturing the released conchospores under natural sunlight from 29 September to 6 October 2005. Germination increased with time and was faster when UV-Bwas excluded using cut-oV Wlters. There were signicant negative eVects of UV-B radiation on growth and cell division of sporelings, with decreases up to 18% for thallus length, between 6 and 18% for thallus width, up to 29% for thallus area, and between 6 and 14% for cell size as compared to PAR-controls. UV-A had a signicant positive eVect on morphogenesis, enhancing the formation of sporelings with cells dividing transversely; on the other hand, UV-B delayed the formation of such sporelings. We also tested the eVects of solar UVR on the growth of P. haitanensis juveniles and found no signiWcant eVects. Our results indicate that UV-A has an important role in the germination and morphogenesis of the species, but on the other hand, sporelings of P. haitanensis are more sensitive to UV-B radiation than juveniles.