根系隔离条件下的谷子亲缘识别

Kin recognition in Setaria italica under the condition of root segregation

在根系隔离情况下,通过研究邻株身份(亲缘株、非亲缘株、陌生株)及其与种植密度(高、低)和土壤养分水平(高、低)交互作用对谷子(Setaria italica)形态学特征和生物量分配的影响,探索谷子地上部分是否能够识别亲缘邻株,以及谷子的这种亲缘识别能力对环境因子如何响应。结果显示:1)亲缘组谷子叶生物量分配显著降低,茎秆显著增粗,暗示着亲缘组谷子植株间减少竞争,并增强对当地多风气候的适应。而非亲缘组谷子叶生物量分配显著增加,表明非亲缘组谷子植株间竞争较强。2)与非亲缘组相比,陌生组谷子种子生物量分配显著增加,株高显著减少,表明陌生组谷子植株通过不对称竞争(与邻株糜(Panicum miliaceum)植株相比,株高显著增加),进一步限制邻株(糜)生长,从而增强竞争能力,同时,将更多的生物量投资于繁殖,增加适合度。3)在高密度种植条件下,谷子茎生物量和叶生物量分配在各邻株身份处理间无显著差异,而在低密度种植条件下,与非亲缘组相比,亲缘组谷子茎生物量显著增加,叶生物量分配显著减小;随着种植间距的增大(种植密度减小),亲缘组谷子叶生物量分配显著减少,而非亲缘组和陌生组叶生物量分配在高、低种植密度条件下无显著差异。4)在低土壤养分条件下,亲缘组和非亲缘组谷子叶生物量分配无显著差异,前者穗长显著小于后者,而在高土壤养分条件下,亲缘组谷子叶生物量分配显著小于非亲缘组,前者穗长显著大于后者。结果表明,在根系隔离的情况下,谷子能够识别亲缘邻株,且谷子地上部分竞争信号在亲缘识别过程中扮演重要角色。较低种植密度和较高土壤养分水平有利于谷子亲缘识别能力的表达。

Aims Kin recognition may play an important part in the performance and productivity of crop plants. However, so far, little is known about whether crop plants can recognize their kin neighbors. The aim of this study was to explore kin recognition in Setaria italica, and its responses to changes in environmental and biological conditions. Methods A field experiment was conducted in the suburb of Shanghai. Setaria italica grew with different neighbors（kin, non-kin and strangers）, under the condition of root segregation and different plant densities（high and low） and soil nutrient levels（high and low）, respectively. We investigated how neighbor identity and its interactions with plant density and soil nutrient level affected the morphology and biomass allocation of S. italica. Important findings Under the condition of root segregation, 1） Leaf biomass allocation and stem diameter of plants in the kin groups significantly decreased and increased, respectively, suggesting that plants of S. italica in the kin groups reduced inter-individual competition, and adapted to the local windy climate. 2） Compared with the non-kin groups, plants in the stranger groups significantly increased the biomass allocation to seeds, while plant height decreased significantly, suggesting that the plants of S. italica in the stranger groups may reduce the growth of their neighbors due to asymmetric competition（S. italica significantly increased height compared with the neighboring plants, Panicum miliaceum）. Therefore, the S. italic plants in the stranger groups allocated more biomass to reproduction and increased fitness than those in non-kin groups. 3） Under the condition of high plant density, no significant differences were found in stem biomass and leaf biomass allocation of plants among different neighbor identity treatments. While under the condition of low plant density, compared with the non-kin groups, biomass allocation to stem and leaf in the kin groups significantly increased and decreased, respectively. As the plant density decreased, plants in the kin groups decreased leaf biomass allocation significantly, while plants in the non-kin and stranger groups did not show such a response. 4） Under the condition of low soil nutrient level, no significant difference was found in leaf biomass allocation between the kin and non-kin groups, while the ear length of plants in the kin groups decreased significantly. Under the condition of high soil nutrient level, the biomass allocated to leaves in the kin groups decreased significantly, while ear length increased significantly compared with the non-kin groups. Therefore, under the condition of root segregation, plants of S. italica showed the ability to recognize their kin neighbors, and the aboveground competitive cues may play important roles in the course of kin recognition in S. italica. Lower plant density and higher soil nutrient level may facilitate the ability of kin recognition in S. italica.