An orthogonal design of light factors to optimize growth, photosynthetic capability and metabolite accumulation of Anoectochilus roxburghii (Wall.) Lindl.

Light is one of the key environmental factors influencing plant physiology and biochemistry, and light intensity (I),red and blue photon flux ratio (S) and photoperiod (P) are important light factors affecting plant growth, photosynthetic capability and metabolite accumulation. Nevertheless, little is known regarding the optimal combination of the three light factors for plant artificial cultivation and the effect of combination on plant physiology. In this study, Anoectochilus roxburghii(Wall.) Lindl., which is an important Chinese medicinal plant, was cultivated and continuously investigated under artificial light environment that the three light factors (I, S, P) were designed according to L-16(4(3))orthogonal array. The results showed that all the light factors significantly affected leaf area, stem diameter, plant length, dry weight, flavonoids and polysaccharides contents. Red and blue photon flux ratio and photoperiod significantly influenced pigment content, but light intensity did not significantly influence it. Chlorophyll fluorescence analysis showed that high light intensity not only could lead light stress, but also could promote photosynthetic capacity by combination with red and blue photon flux ratio and photoperiod. The improved protocols I2S2P2(I=60 mu molm(- 2)s(- 1), S=2:1 and P=10 h) and I4S1P4(I=100 mu mol m(-2)s(- 1), S=1:1 and P=14 h) were validated and demonstrated to be the optimal combinations for growth and total polysaccharides content (I2S2P2) and for flavonoids contents (I4S1P4) respectively. This study also demonstrated that orthogonal array design is an efficient way to establish improved protocols of light for artificial cultivation of A. roxburghii.

Automated summary

This study investigated the impact of light intensity, red and blue photon flux ratio, and photoperiod on the growth and physiology of Anoectochilus roxburghii under artificial light conditions. The results showed that all three light factors significantly influenced plant growth and metabolite accumulation. Optimal combinations were identified for growth and metabolite content, demonstrating the efficiency of orthogonal array design in establishing improved light protocols for artificial cultivation.