GROWTH AND PHOTOSYNTHESIS TEMPERATURE CHA RACTERISTICS OF THE STERILEULVA-PERTUSA

Growth and photosynthesis temperature characteristics of the sterile U lva pertusa (sterile type) were studied and compared with the wild U. pertusa (wild type) collected from the low water mark at Tana in Yamag uchi Prefecture and at Shimoda in Shizuoka Prefecture. The sterile typ e and the wild type at the Tana site in summer were cultured at 10, 15 , 20, 25, 30, and 35 degrees C. The sterile type grew faster than the wild type from 20 to 30 degrees C. Photosynthesis temperature relation ships of both types were measured with two seasons. The photosynthetic rate, measured from 5 to 35 degrees C every 5 degrees C using the sam e fronds, was higher in the sterile type than in the wild type at the Tana site in autumn over 25 degrees C. The relative photosynthetic rat e, expressed as values relative to that at 20 degrees C, was also high er in the sterile type than in the wild type both at the Tana site and at the Shimoda site in summer over 25 degrees C, while the respirator y rate from 10 to 35 degrees C was lower in the sterile type than in t he wild type at the Shimoda site in summer. These results indicate tha t the rapid growth of the sterile type from 20 to 30 degrees C is main ly caused by a high photosynthetic rate and a low respiratory rate.