Selection and characterization of a new strain (S-15) with a suitable quantity of archeospores released in Pyropia yezoensis

In terms of field application, the archeospores released from Pyropia yezoensis blades are of great significance for increasing the number of seedlings on the cultivation nets, prolonging the harvest period, and improving yield and quality. To select a new strain of P. yezoensis with fast growth, good quality, high-temperature resistance, and a suitable quantity of archeospores released, an intraspecific hybridization was carried out between the improved strain (A-18) with almost no archeospores released and Py-26W’ strain with a large quantity of archeospores released. A new strain S-15 was then isolated from the offspring. From 15 days of age, the total number of archeospores released from S-15 per blade for 21 consecutive days was 1353, while that from A-18 was only 6 (P < 0.05). After being cultured for 60 days, the mean length of the S-15 blades was 156.8 cm, which is 1.2 times longer than that of the A-18 blades. When blades aged 30 days (cultured at 18 ℃) were further cultured at 25 ℃ for another 30 days, both A-18 and S-15 showed a slow increase in blade length, but the Fv/Fm value of A-18 blades decreased by 13.0