Plant Growth and Energy Use Efficiency of Purple Basil as Affected by Different Green-Blue Light Ratios

The objective of this experiment was to investigate the effects of different green-blue light ratios (G/B) with 50% percent red light (R, 660nm) on the growth, morphology, light response capacity, and light use efficiency (LUE) of purple basil plants (Ocimum basilicum Linn.). Purple basil seedlings were subjected to seven light quality treatments of RB, RG
1
B
7
, RG
1
B
3
, RG
1
B
1
, RG
3
B
1
, RG
7
B
1
, and RG for 25 days after transplanting. Growth parameters, photosynthetic parameters, and light utilization efficiency of purple basil plants were measured on day 25 after transplanting. Our results showed that the light response capacity of purple basil decreased when G/B>1, compared with RB, but the height and leaf area still increased under RG
3
B
1
and RG. Moreover, the LUE and fresh weight increased under RG. When G/B≤1, RG
1
B
3
increased shoot fresh weight and leaf area. Based on the above results, RG
1
B
3
and RG can be considered suitable light quality combinations for purple basil's yield and growth rate. These results can provide a technical support for energy-saving and efficient production models of purple basil.