Synergistic effects of temperature and light intensity on growth and physiological performance in Chaetoceros calcitrans

Abstract Temperature and light intensity are two closely related and inseparable key environmental factors in natural cultivation of Chaetoceros calcitrans. Herein, two temperatures (20 and 30 °C) coordinated with three light intensities (40, 120 and 200 μmol m−2 s−1) were employed to C. calcitrans cultivation. During which, the growth rate, photochemical efficiency, antioxidant ability and photosynthetic pigment contents were evaluated. Results showed that regardless of light intensity, C. calcitrans grown at 30 °C always had higher growth rate and biomass than that at 20 °C. Meanwhile, stronger light intensity exhibited a significant advantage for growth performance of C. calcitrans than that of 40 μmol m−2 s−1 in both temperatures, but no significant difference existed between 120 and 200 μmol m−2 s−1. However, the values of Fv/Fm and Fv’/Fm’ decreased with the increase of light intensity in both temperatures, indicated that stronger light intensity damaged the photosynthetic efficiency. Consistently, similar changing pattern was found in the content of chlorophyll a. However, the oxidative stress was enhanced in C. calcitrans grown with lower light intensity as evidenced by the SOD activity and content of β-Carotene, which might be related to the poor growth performance. Collectively, temperature and light intensity have a strong synergistic effect on the growth of C. calcitrans, but the light intensity does not have to be too strong, for example, higher than 120 μmol m−2 s−1. Notably, high temperature and strong light intensity will damage the photosynthetic efficiency and pigment content, which should also be considered in actual production of C. calcitrans.