Application of light-emittingdiodes (LEDs) in the extensionof the cultivation period of Spirulina in Northern Vietnam

Spirulina (Arthrospira platensis) is cultured in Vietnam mainly as a functional food for humans and supplementary food for aquatic species. In the North, the most suitable time to cultivate Spirulina is from early May to late September. Other times, due to the decrease in light intensity and temperature, the growth of Spirulina significantly reduced and gave low yield, especially in the period from December to the end of February. This study investigated the influence of LEDs light on the growth of Spirulina during the periods from early March to late April (T3-T4), from early October to late November (T10-T11), and from early December to late February (T12-T2) in Hanoi. The results showed that the continuous irradiation of red LEDs increased the yield of Spirulina and pigments, phycocyanin, and chlorophyll in the two stages (T3-T4) and (T10-T11). The irradiation of both red and blue LEDs did not show a significant effect in the period T12-T2. Green LEDs did not significantly affect the growth of Spirulina. The research results provided an initial basis for the application of red LEDs to the extent of the cultivation time of Spirulina in the North of Vietnam