The cultivation of Chondrus crispus. Factors affecting growth under greenhouse conditions

Abstract

Two methods of growing Chondrus crispus in flowing seawater in tanks in a greenhouse were used in determining some of the conditions required for the cultivation of C. crispus. In one system, individual plants were tethered to a fixed support, and in the other, the plants were allowed to float freely in circulating seawater. The addition of nitrate or ammonia and phosphate increased the growth rate, whereas iron did not. Urea was not a good source of nitrogen. Well nourished plants had a relatively high nitrogen and water content and were richly pigmented. Such plants, when grown in nutrient-deficient seawater, gradually bleached and the percentage of dry matter and carrageenan increased. Growth under conditions of continuous illumination was superior to normal illumination with alternating day and night periods. Seasonal variation in growth rates was closely correlated with the mean ambient temperature of the seawater. Epiphytes were a serious problem but became less so as optimum conditions for growth of C. crispus were approached. A single plant (T4), observed to have a relatively rapid growth rate, was selected and a clone was established by vegetative propagation.