Mašková Tereza, Herben Tomáš
Faculty of Science Department of Botany Charles University in Prague Prague Czech Republic.
Ecol Evol. 2018 Jun 22;8(14):7143-7150. doi: 10.1002/ece3.4238. eCollection 2018 Jul.
Root:shoot (R:S) biomass partitioning is one of the keys to the plants' ability to compensate for limiting resources in the environment and thus to survive and succeed in competition. In adult plants, it can vary in response to many factors, such as nutrient availability in the soil or reserves in the roots from the previous season. The question remains whether, at the interspecific level, reserves in seeds can affect seedlings' R:S ratio in a similar way. Proper allocation to resource-acquiring organs is enormously important for seedlings and is likely to determine their survival and further success. Therefore, we investigated the effect of seed mass on seedling R:S biomass partitioning and its interaction with nutrient supply in the substrate. We measured seedling biomass partitioning under two different nutrient treatments after 2, 4, 6, and 12 weeks for seventeen species differing in seed mass and covering. We used phylogenetically informed analysis to determine the independent influence of seed mass on seedling biomass partitioning. We found consistently lower R:S ratios in seedlings with higher seed mass. Expectedly, R:S was also lower with higher substrate nutrient supply, but substrate nutrient supply had a bigger effect on R:S ratio for species with higher seed mass. These findings point to the importance of seed reserves for the usage of soil resources. Generally, R:S ratio decreased over time and, similarly to the effect of substrate nutrients, R:S ratio decreased faster for large-seeded species. We show that the seed mass determines the allocation patterns into new resource-acquiring organs during seedling development. Large-seeded species are more flexible in soil nutrient use. It is likely that faster development of shoots provides large-seeded species with the key advantage in asymmetric above-ground competition, and that this could constitute one of the selective factors for optimum seed mass.
茎（R:S）生物量分配是植物补偿环境中有限资源从而在竞争中生存并取得成功的关键能力之一。在成年植物中，它会因许多因素而变化，比如土壤中的养分有效性或前一季根系中的储备。问题依然存在：在种间水平上，种子中的储备是否能以类似方式影响幼苗的R:S比率。对资源获取器官进行合理分配对幼苗极为重要，很可能决定其生存及后续的成功。因此，我们研究了种子质量对幼苗R:S生物量分配的影响以及它与基质中养分供应的相互作用。我们对17种种子质量和覆盖度不同的物种，在两种不同养分处理下，于2周、4周、6周和12周后测量了幼苗的生物量分配。我们运用系统发育信息分析来确定种子质量对幼苗生物量分配的独立影响。我们发现种子质量较高的幼苗其R:S比率始终较低。不出所料，基质养分供应较高时R:S比率也较低，但基质养分供应对种子质量较高的物种的R:S比率影响更大。这些发现表明种子储备对于土壤资源利用的重要性。一般来说，R:S比率会随时间下降，并且与基质养分的影响类似，大种子物种的R:S比率下降得更快。我们表明种子质量决定了幼苗发育过程中向新的资源获取器官的分配模式。大种子物种在土壤养分利用上更灵活。地上茎的更快发育可能为大种子物种在不对称地上竞争中提供关键优势，这可能构成种子最优质量的选择因素之一。
