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Biomass and Nutrient Allocation of Lilium pumilum

细叶百合的生物量和营养分配


以栽培的2年生细叶百合(Lilium pumilum)为材料,于2000年的生长季从蕾期至种子成熟期进行6次取样,对其各器官生物量和氮、磷元素的配置进行了动态研究。结果表明,细叶百合虽然以种子繁殖为主,但在整个生长季用于生殖器官的生物量投资的比例并不很大,大量干物质分配到地下器官鳞茎中(平均为60.17%);茎、叶的生物量分配比例仅次于鳞茎;雄蕊生物量分配比例明显高于雌蕊。在叶萌动及展叶初期植株全氮百分含量最高;从春季萌动至秋季果实成熟,叶中的氮呈逐渐递减的趋势;茎和生殖器官的全氮含量在蕾期最大;生殖器官与叶、鳞茎的全氮含量相关显著。磷在生殖器官的含量较高,这与磷在植物有性生殖过程中的重要作用相一致;生殖器官与茎的全磷含量相关显著。地下器官全氮、全磷随季节变化有增多的趋势;地上各器官全氮、全磷相关显著,随季节变化有明显减少的趋势。

In order to understand the relationship between biomass and nutrient allocation of Lilium pumilum, a wildly spread perennial herb in China mainly used for medicinal purposes (bulbs are harvested) and as an ornamental, a study on the biomass of vegetative organs, reproductive organs and allocation of N and P in different developmental stages was carried out . The experimental material was obtained from the garden of Northeast Forestry University where L. pumilum had been seeded in a high bed of black soil in spring 1998 under conditions of full sunlight and received treatment of manual weeding, watering and no fertilization.In 2000, samples were taken from May to November from blooming plants of L. pumilum at 6 different stages: bud stage (May 24th); middle period of bud spreading (June 11th); floral phase (June 26th); early fruit-set phase (July 26th); fructescence (August 29th); and seed maturation phase (October 3rd). Thirty individual plants together with their intact underground organs were carefully washed. Every plant was divided into bulb, stem, leaf, bud, flower and fruit (shell and seed), placed into envelopes, dried at 80 ℃, and weighed. We determined the mean biomass of each organ at each growth period and then calculated the ratio of the mean biomass to total biomass. Also, two replicate samples of each tissue were analyzed for N and P content and the average percentweight of total-N and total-P was recorded.The results showed that the percent mean biomass averaged across all developmental stages decreased in the following order: bulbs (60.17%): leaves (13.28%): stems (12.84%): reproductive organs (9.18%); and roots (5.78%). The large investment in the bulb might be a self-protective mechanism for a population of perennial bulbaceous plants as a means for maintaining their long term development. The bulb reached maximum biomass at the early bud stage, and seed maturation phase and the minimum at floral stage. If we want these results indicate that to harvest edible bulbs, the fruitlet should be removed at the post floral stage to increase bulb biomass at the post floral stage and thus improve the bulb harvest. Bulbs should be harvested at the period of maximum biomass, that is, at the bulb stage and seed maturation phase. Seasonal biomass dynamics of reproductive organs were negatively correlated with non-reproductive organs.The results revealed that the mean percent total-N in tissues averaged across all development stages decreased in the following order: leaves (2.19%); reproductive organs (1.50%); bulbs (1.16%); roots (1.03%); and stems (0.99%). Total-N tissue concentrations reached their peak during leaf sprouting and early leaf spreading phase; this occurred when the N content of the reproductive organs were positively correlated with leaf N content and negatively correlated with that in the bulb. The mean total-P content decreased in the following order: reproductive organs (0.035 6%); bulbs (0.031 6%); stems (0.027 8%); roots (0.026 6%); and leaves (0.026 4%). The total-N content of the reproductive organs was positively correlated with that in the stem. This research also revealed that the content of total-N and total-P in aboveground organs tended to increase while organs underground tended to decrease with changing seasons.