ON THE CULTIVATON OF SPORELINGS BY SUMMERLNG GAMETOPHYIES OF UNDARIA PINNATFIDA (HARV.) SUR. IN POOL

Undaria plnnatifida (Harv.) Sur, in one of the important economic srawerds of China. So Far it has not yet been brought under cultivation by the artificial metliod,because there is no effective method to cultivate tl;e sparelings. Although the cultivalion of aporelinga was succeasful to a certain extent in the sea, there still exist some handicaps which hinder the growing of the sporelings. The spores of some other aeaweeds and larvae of various invertebrates adhere to the same substratum an which Undaria spares set, and hence they chock the development of the aporea of Undaria. Besides, the artificial substrata are often washed away- by the waves,so the cultivation in the aea is not safe during the aummer. Tseng, Sun and Wu (1955) suggested that cultivation of sporelings of Undaria be made at low temperature. According to our studies the gameiaphytes of Undaria grow well at 25-27℃, and the temperature of sea water seldom rises above 28℃ at Tsingtao. As temperature is oat a limiting factor far cultivating gametophytcs, so loo tempera.Lure method seems not neceasary. We collected the spores of Undaria in July and eulti-vhted them in pools indoors.When temperature dropped to below 25℃, the gametophytea began to develop into aporophytes. Under good light condition the sporelings grew larger and denser. When the temperature of the aea water dropped down to 22--23℃,the sporelings were transfered from the pool to the sea. A month later the sporelings grew to such sizea as 1.8-2.3 cm. There are three advantages in the artificial cultivation of Llndaria spnrelings in pools; (1)The temperature of sea water in pools lowers more quicl.ly than the tcmpersiure of water in the sea after middle autumn. Under lower temperature the young sporophytes grow larger than those in open sea. (2)Filtered sea water is free from various marine invertebrates, an that Undaria sporelings may grow denser. (3)This method of cultivation in pools is safe. sim ple and evono mical along northern China coast.