Effects of supplemental lighting on growth and physiological responses of Norway spruce (Picea abies (L.) H. Karst) from different provenances

Fluorescent lamp is the best light source to promote growth of Norway spruce (Picea abies (L.) H. Karst) seedlings but a significant difference in such effect exists among different provenances. Clarifying the mechanism of this difference is of important value to develop optimal strategy of supplemental lighting for seedlings from different provenances. In this study, fluorescent lamps were used to illuminate Norway spruce seedlings in greenhouse from four different localities for two continuous growth cycles and the relationship between seedling growth and endogenous hormones as well as polyphenols was analyzed. The results showed that: 1) The average height and diameter of seedlings were 33.48 cm and 5.12 mm, which is 8.38 and 3.50 times those under control, respectively, reaching the requirement of outdoor breeding. 2) The levels of IAA, GAs, ZT, ZT/IAA and ZT/GAs of seedlings with supplemental lighting treatment were significantly higher than those of control; however, there were no significant differences in levels of polyphenols (except for p-hydroxybenzoic acid) and corresponding ratios. 3) Under supplemental lighting treatment, the seedling growth traits were significantly affected by provenance. The average height of DNS107 seedlings (47.50 cm) was significantly higher than that from other provenances, 14.10 cm higher compared to the provenance NS03CK10, the lowest of the four. 4) Among provenances, there were significant differences in the contents of auxin, gibberellins, zeatin and their ratios, catechin, p-hydroxy benzoic acid and total phenolic acids. What’s more, the provenance with the best growth performance had also the highest contents of auxin and gibberellins. One year after supplemental lighting treatment, extremely significant, positive correlations were both found between auxin content and second-year seedling height, and between gibberellins content and length of new shoots in the second year. These results showed that contents of auxin and gibberellins were the main physiological factors promoting growth of Norway spruce seedlings illuminated by fluorescent light and causing the difference among provenances. Study of supplemental lighting measures for improving auxin and gibberellin levels of different provenances is conducive to building a technique system of supplemental lighting and improving the level of seedling cultivation for each provenance of Norway spruce.