Wang Shu, Li Lei, Zhou Dao-Wei
College of Forestry Forest Ecology Research Center Guizhou University Guiyang China.
Jiangxi Province Key Laboratory of Watershed Ecosystem Change and Biodiversity, Center for Watershed Ecology, Institute of Life Science and School of Life Sciences Nanchang University Nanchang China.
Ecol Evol. 2021 Jul 7;11(15):10590-10599. doi: 10.1002/ece3.7868. eCollection 2021 Aug.
How plants cope with increases in population density via root plasticity is not well documented, although abiotic environments and plant ontogeny may have important roles in determining root response to density. To investigate how plant root plasticity in response to density varies with soil conditions and growth stages, we conducted a field experiment with an annual herbaceous species ().
Plants were grown at low, medium, and high densities (13.4, 36.0, and 121.0 plants m, respectively), under fertile and infertile soil conditions, and a series of root traits were measured after 30, 50, and 70 days.
Root allocation increased, decreased, or canalized in response to density, depending on soil conditions and stages of plant growth, indicating the complex effects of population density, including both competitive and facilitative effects.
Root allocation was promoted by neighbor roots at early stages and in abundant resource availability, due to low-to-moderate belowground interactions among smaller plants, leading to facilitation. As plants grew, competition intensified and infertile soil aggravated belowground competition, leading to decreased root allocation in response to density. Root growth may be more likely restricted horizontally rather than vertically by the presence of neighbor, suggesting a spatial orientation effect in their responses to density. We emphasized the importance of considering effects of abiotic conditions and plant growth stages in elucidating the complexity of density effects on root traits.
尽管非生物环境和植物个体发育在决定根系对密度的响应方面可能具有重要作用，但植物如何通过根系可塑性应对种群密度增加的情况尚无充分记录。为了研究植物根系对密度的可塑性响应如何随土壤条件和生长阶段而变化，我们对一种一年生草本植物进行了田间试验。
将植物分别种植在低密度、中密度和高密度（分别为13.4、36.0和121.0株/平方米）条件下，设置肥沃和贫瘠两种土壤条件，并在30天、50天和70天后测量一系列根系性状。
根系分配随密度增加而增加、减少或趋于稳定，这取决于土壤条件和植物生长阶段，表明种群密度具有复杂影响，包括竞争和促进作用。
在早期阶段以及资源丰富时，相邻根系会促进根系分配，这是因为较小植株之间地下低到中等程度的相互作用会产生促进作用。随着植物生长，竞争加剧，贫瘠土壤会加重地下竞争，导致根系分配随密度增加而减少。相邻植株的存在可能更倾向于在水平方向而非垂直方向限制根系生长，这表明它们对密度的响应存在空间取向效应。我们强调了在阐明密度对根系性状影响的复杂性时考虑非生物条件和植物生长阶段影响的重要性。
