Effect of light condition on embryo and larva development of Babylonia areolata

Babylonia areolata is well-liked and has great market value, but its embryonic development success rate is very low and it is difficult to meet the market demand.. In this study, the effects of light intensity, light quality and photoperiod on fertilization rate ( FR ), hatching rate ( HR ) and metamorphosis rate ( MR ) during embryonic development of B. areolata were researched by factorial design. In addition, the result was analyzed by establishing regression models to optimize light conditions and find the best combination level of light quality, light intensity and photoperiod for embryonic development of B. areolata. The results showed that compared with other light conditions, green light had a better promoting effect on embryo incubation, and FR、HR and MR had maximum of 89.84%, 90.34% and 91.49%, respectively when photoperiod was 12L∶12D and the light intensity was 16 μmol/(m²·s). However, under the condition of blue light, FR, HR and MR were lower than other light qualities for any combination of light intensity and photoperiod levels, with maximum values of 49.71%, 50.26% and 43.49%, respectively. With the increase of light intensity and the extension of light time, the three indexes decreased more and more obviously, which indicated that blue light inhibited embryonic development of B. areolata. Through the establishment of model analysis found that under different light quality conditions, FR, HR and MR were significantly affected by the linear, interaction and quadratic effects of light intensity and photoperiod, that is, under any light quality condition, there was interaction effect between light intensity and photoperiod. The optimal light conditions were optimized when the light quality was used as a classification variable, it was found that under the condition of green light, the light intensity was 13.70 μmol/(m²·s), and the illumination time was 15.54 h, the FR, HR and MR reached the optimal value, which were 91.359 %, 88.637 % and 92.023 %, respectively. However, under blue light conditions, at a light intensity of 14 and a light duration of 6 h, the values of FR, HR and MR were 45.28 %, 47.69 % and 45.04 %. Compared with other light qualities, under the optimized conditions, the effect of green light on the embryonic development of B. areolata was the most obvious, followed by red, white light and blue light. In summary, appropriate light intensity and light duration can act synergistically with light quality, and in actual production, green light conditions can effectively improve the emergence efficiency and seedling quality of B. areolata, and blue light has an inhibitory effect on embryo development.