Growth promotion and amino acid profiles in Spinacia accessions under alternating red and blue light

Alternating irradiation of red and blue light has been reported to promote the growth of several crops, caused by modifications in metabolite biosynthesis. In this study, ten Spinacia accessions, including both cultivated and wild spinach, were grown under alternating and simultaneous red/blue light irradiation, with a white fluorescent lamp used as a control. The results indicated that alternating red and blue light significantly increased fresh weight of most accessions. Additionally, alternating irradiation enhanced accumulation of glutamic acid, glutamine, and aspartic acid. In contrast, the levels of gamma-aminobutyric acid (GABA) and asparagine significantly decreased under alternating red and blue light, while they reached their highest values under simultaneous irradiation. The results suggest that different irradiation regimes influence plant growth by modulating enzyme activity in metabolic processes, leading to the accumulation or depletion of specific amino acids. Among the tested accessions, ‘CGN25120’ exhibited the highest increase in fresh weight when subjected to alternating irradiation, showing a remarkable improvement of 100.3% compared to fluorescent irradiation. Similarly, ‘CGN09511’ experienced a 153.1% increase in fresh weight without a significant reduction in amino acid content. Meanwhile, the wild accession ‘CGN25085’ (Spinacia tetrandra) demonstrated exceptionally high amino acid content, suggesting it could be a valuable genetic resource for plant breeding.