低磷胁迫对雷公藤幼苗形态指标及生物量的影响

采用土培的方法,研究了磷(P)胁迫对雷公藤(Tripterygium wilfordii Hook.f.)1年生和3年生幼苗在一个生长季内形态指标及生物量的影响。结果表明:低P处理显著抑制了雷公藤幼苗地上部分的增长,而对地下部分的影响较小,导致根冠比的增加,在相同P水平处理下,3年生雷公藤的根冠比高于1年生的;低P胁迫显著影响了雷公藤的生物量积累及分配,雷公藤幼苗总生物量及1年生雷公藤细根生物量占根系生物量的比例下降,根系生物量在总生物量中的比例及3年生雷公藤细根生物量在根系生物量中的比例上升。这表明3年生雷公藤对P逆境有更好的适应机制,对低P林地套种雷公藤的苗龄选择有参考价值;雷公藤幼苗的株高、最长枝均与生物量呈显著的正相关,可作为耐低P雷公藤良种选育中优良性状的指标。中轻度的P胁迫不显著影响根系生物量的积累,维持较大比例的根系是雷公藤适应低P胁迫的主要策略。

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

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.