Effects of a weak supply of light at night on the growth and quality components of tea plants

Supplying artificial light is widely used in crop cultivation to improve yield and quality. In this study, we investigated the effects of a weak supply of light (WSL) on the growth and quality components of tea plants. Starting from mid-winter (20 January 2021), the purple tea (Camellia sinensis) cultivar ‘Ziyan’ was exposed to four different spectra at an intensity of 2 μmol · m⁻² · s⁻¹ or 5 μmol · m⁻² · s⁻¹ for 3 h or 5 h after sunset. The field observations showed that the sprouting index, which represents the time and speed of bud flush, was significantly higher in most of the WSL treatments than in the control (CK, p < 0.01). The total content of catechin in the harvested leaves of 3 WSL treatments was 11.51%–18.94% higher than that of the CK, but the content of anthocyanin of 4 WSL treatments unexpectedly decreased by 6.77%–11.69% (p < 0.05). The differences in yield, free amino acids and caffeine contents between the WSL treatments and CK were not significant. We concluded that the WSL treatments during the early spring night had positive impacts on the growth and some quality components of tea plants.