Functional growth, photosynthesis and nutritional property analyses of lettuce grown under different temperature and light intensity

ABSTRACT

There is a growing interest in the impact of light intensity and temperature on vegetable growth and dietary quality characteristics. Lettuce (Lactuca sativa L.), as one of the model vegetables in plant factories, was grown under two light levels (G₁: 160 µmol m^–2 s^–1, G₂: 200 µmol m^–2 s^–1) with different day/night temperatures (T₁: 20 ± 1°C/15 ± 1°C, T₂: 24 ± 1°C/19 ± 1°C) to investigate mutual effects of light intensity and temperature on its growth and quality properties. The results revealed that the T₂G₂ treatment showed higher plant height, biomass and net photosynthetic rate, while T₁G₂ resulted in decreased leaf area and lower maximum photochemical efficiency of photosystem II (Fv/Fm) compared to T₁G₁. Simultaneous increases in light intensity and temperature based on T₁G₁ significantly increased the contents of anthocyanin, vitamin C (Vc) and soluble protein by 58%, 21% and 172%, respectively. The higher light intensity promoted the nutritional values of lettuce, characterised by lower nitrate level and soluble protein contents. Principal component analysis showed a negative collinearity between the nitrate content and soluble protein and Vc contents. In conclusion, light intensity and temperature co-regulated the lettuce’s growth and development, and their simultaneous increases better for growth and nutritional values of lettuce. These results provide a better understanding of the cultivation of plants in an artificial plant factory while maintaining yield and quality.

KEYWORDS:

• Interactive effects
• light intensity
• temperature
• lettuce
• quality
• yield

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the [National Key R&D Program of China] under Grant [2017YFB0403903]; [National 863 High Technology Program of China] under Grant [2013AA103003] and the Student Research Training Project of Nanjing Agricultural University [1003A13].