遮阴对千根草构件性状、克隆生长及繁殖策略的影响

为开发和利用野生乡土草坪草种质资源千根草(Euphorbia thymifolia),探究其耐阴性强弱与形成机理,通过设置0(CK)、30％、50％、70％的4个遮阴度,经4个月夏季室外处理后,测定基株的构件性状、生物量结构、克隆效率指数及有性繁殖指数等参数,分析遮阴下千根草的生长和繁殖策略.结果表明,1)千根草通过降低叶片数、叶面积、匍匐茎长和分枝强度(P<0.05),形成适应遮阴度的构件数量和质量性状.2)叶性状对遮阴响应顺序为叶数>总叶面积>叶长>单叶面积>叶宽>叶厚,茎性状对遮阴响应顺序为分枝强度>株高>匍匐茎长>分枝密度>一级分枝数,根性状对遮阴响应顺序为不定根数>主根直径>侧根数>主根长.3)遮阴降低了基株生物量(P<0.05),千根草通过调整构件生物量分配比,形成适应遮阴生境的生长策略.4)千根草通过降低有性繁殖分配与繁殖指数应对>30％遮阴(P<0.05),通过降低克隆结构生物量和克隆效率指数适应遮阴生境(P<0.05).综上,千根草为喜光植物,可通过调节构件性状与生物量结构,形成与遮阴度相匹配的克隆生长与有性繁殖策略.

Effects of shading on phenotypic plasticity,clonal characteristics,and reproduction index of Euphorbia thymifolia

Euphorbia thymifolia is a wild native turfgrass germplasm resource, whose shade tolerance and coping mechanisms determined its values of development and utilization. In this experiment, we treated the seedlings of E. thymifolia under four shading degrees of 0 (CK), 30%, 50%, and 70% for four months. In summer, the component properties, biomass structure, cloning efficiency indexes and sexual reproduction indexes of the genet were determined, to analyze the growth and reproduction strategy of E. thymifolia under different degrees of shading. The results showed that: 1) E. thymifolia exhibited altered quantity and quality character components by decreasing leaf number, leaf area, stolon length, branching strength, root diameter and so on (P < 0.05), to adapt to or respond to shade stress. 2) The response order of leaf characteristics to shading was number > total leaf area > length > single leaf area > width > thickness, that of stem characteristics was branch strength > plant height > stolon length > branch density > primary branch number, and that of root characteristics was indefinite root number > main root diameter > lateral root number > main root length. 3) With a decrease of genet biomass under shading (P < 0.05), E. thymifolia adjusted the component biomass allocation ratio to form a growth strategy adapted to the shading degree. 4) E. thymifolia could reduce the sexual reproductive allocation and reproductive index to cope with > 30% shading (P < 0.05), simultaneously decreasing the clonal structure biomass and cloning efficiency index to adapt to the shading habitat (P < 0.05). In summary, E. thymifolia is a light-loving plant, with a strong ability to adjust the component traits and biomass structure according to shading degrees, and thus, clonal growth and sexual reproduction could be adapted to the environment.