High-temperature resistance of the thin-blade strain of Pyropia haitanensis and its pilot cultivation in mariculture farm

Abstract

The characteristics of the thin-blade strain (HR-5) were evaluated and compared with the wild type strain (WT) in Pyropia haitanensis in laboratory studies and pilot scale tests in a mariculture farm. The results showed that, at the suitable temperature (23 °C) and high temperature (27 and 29 °C) for 7 days, the survival rates of conchospores were 86.6, 73.5, and 42% in HR-5, which were 3.0, 13.3, and 3.2% higher than those of WT, respectively, but showing no significant difference between them (P > 0.05). When the F1 gametophytic blade of HR-5 and WT were first cultured at 23 °C for 25 days and then cultured at 23, 27, and 29 °C for another 20 days, the mean blade length increased by 13.1, 8.7, and 6.4 times for HR-5, and only 8.9, 4.6, and 3.5 times for WT compared with the original lengths, respectively. Three blade harvests were done in sea cultivation, and the mean wet weight of HR-5 blades was 0.17, 0.27, and 0.42 g per blade, which were 142.9, 49.2, and 38.3% higher than those of WT, respectively, showing significant differences between them (P < 0.05); the mean thickness of HR-5 blades was 26.0, 28.5, and 29.6 μm, decreasing by 31.9, 40.2, and 46.5% in contrast with that of WT, respectively, showing highly significant differences between them (P < 0.01); the phycobiliprotein content of HR-5 blades was 80.6, 75.3, and 61.8 mg g−1, increased by 12.2, 26.0, and 30.9% in contrast with that of WT, respectively. The results confirmed that the high-temperature resistance of HR-5 conchospores was similar to WT, while the blades of HR-5 were thinner and grew faster with higher contents of the major photosynthetic pigments as compared with WT. It therefore has the potential to be developed into a new variety with thin thallus suitable for cultivation along the coast of South China and promote the transformation and development of the industry of P. haitanensis.