An orthogonal design for optimization of growth conditions for all life history stages of Gracilariopsis lemaneiformis (Rhodophyta)

Gracilariopsis lemaneiformis is an important economic macroalgae worldwide. At present it is mainly cultured by vegetative propagation, which is labor intensive, bulky, and requires large amounts of propagating material. To identify the optimal conditions for spore release, spore development, and fertilization success of Gp. lemaneiformis, four levels of each of four factors (light, temperature, salinity, and photoperiod) were tested using an orthogonal experimental design. Variations in temperature and salinity had significant effects on carpospore yield, and the optimal conditions for carpospore release were 20 °C, 35‰, 15 μmol m− 2 s− 1, and 8/16–14/10 h L/D. The main factors that influenced tetraspore release were temperature, light, and salinity, with the optimal combination being 25 °C, 15 μmol m− 2 s− 1, 35‰, and 8/16–14/10 h L/D. Temperature variation also had an effect on spore development, whereas the effects of the other factors were not significant. The optimal conditions for tetraspore development were 25 °C, 45 μmol m− 2 s− 1, 12/12 h L/D, and 25‰, and for carpospore development they were 25 °C, 45 μmol m− 2 s− 1, 30‰, and 12/12 h L/D. Temperature significantly affected fertilization success of male and female gametophytes, whereas salinity, photoperiod, and light intensity had no significant effect (P > 0.05). The optimal combination of factors for fertilization success was 25 °C, 30‰, 12/12 h L/D, and 15–45 μmol m− 2 s− 1. The culture time of sporeling growth was reduced by about 3–4 months in the study, the results of which can also provide valuable information for genetic breeding, large-scale culture of spores, and algal cultivation.

► The effects of multi-factors on life history of Gp. lemaneiformis were studied.
► We obtained the optimal conditions for all life history stages.
► The culture time of spore development was reduced by about 3–4 months in the study.
► We explored the spore culture of Gp. lemaneiformis.
► In addition, the manuscript was processed by the International Scientific Editing.