Effect of Low Phosphorus Stress on Morphological Indexes and Biomass of Tripterygium wilfordii Hook. f. Seedlings

Abstract:

The effects of low phosphorus (P) stress on morphological indexes and biomass of Tripterygium wilfordii Hook. f. seedlings were studied. The results showed that the aboveground growth of seedlings was markedly inhibited under low P stress, and the underground parts had little effects, which causing increment of root-shoot ratio. The root-shoot ratio of 3-year-old seedlings was larger than that of 1-year-old seedlings under the same P level. The biomass accumulation and allocation of T. wilfordii seedlings were significantly affected by low P stress. Under low P stress, the total biomass and the biomass ratio of fine roots to total roots of 1-yearold seedlings decreased, whereas the ratios of root biomass to total biomass, and fine root biomass to total root biomass of 3-year-old seedlings increased. It suggested that 3-year-old seedlings had better adaptive mechanism to low P stress than 1-year-old seedlings, which had reference value for selection seedling age of T. wilfordii in low P woodland. There were significantly positive correlations between T. wilfordii height and length of the longest branch with the biomass, which could be used as index for selecting excellent traits of T. wilfordii to low P insistence. There was not significant effects of moderate and light P stress on root biomass accumulation of T. wilfordii, so that it was main strategy to adapt low P stress for maintain large proportion of roots.

Key words:Low phosphorus stress;Tripterygium wilfordii Hook. f.;Morphological index;Biomass