Early development of germlings of Sargassum thunbergii (Fucales, Phaeophyta) under laboratory conditions.

摘要

Morphology and culture studies on germlings of Sargassum thunbergii (Mertens et Roth) Kuntze were carried out under controlled laboratory conditions. Growth characteristics of these germlings grown under different temperatures (from 10 to 25 degrees C), irradiances (from 9 to 88 micro mol photons m-2 s-1), and under blue and white light conditions are described. The development of embryonic germlings follows the classic "8 nuclei 1 egg" type described for Sargassaceae. Fertilized eggs spent 5-6 h developing into multicellular germlings with abundant rhizoids after fertilization. Under conditions of 20 degrees C, 44 micro mol photons m-2 s-1 and photoperiod of 12 h, young germlings with one or two leaflets reached 2-3 mm in length after 8 weeks. Temperature variations (10, 15, 20, 25 degrees C) under 88 micro mol photons m-2 s-1 significantly influenced the growth rate within the first week, although this effect became less obvious after 8 weeks, especially at 15 and 20 degrees C. Variation in germling growth was highly significant under different irradiances (9, 18, 44, 88 micro mol photons m-2 s-1) at 25 degrees C. Low temperature (10 degrees C) reduced germling growth. Growth of germlings cultured under blue light was lower than in white light. Optimal growth of these germlings occurred at 25 degrees C and 44 micro mol photons m-2 s-1.