不同根系分隔方式对栗和茶幼苗生长的影响

研究不同根系分隔方式对栗(Castanea mollissima)/茶(Camellia sinensis)间作地下部分相互作用和植物种间互作动态的影响, 探究根系互作对植株株高、基径和根系生长的影响, 可为栗/茶复合经营模式的可持续发展提供科学指导。该研究以栗/茶间作和相应单作为研究对象, 运用盆栽实验的根系分隔技术(塑料膜分隔、尼龙网分隔和不分隔), 分别利用logistic生长模型模拟栗和茶株高与基径生长动态过程, 利用幂函数研究株高-基径的异速生长关系, 并从细根发育角度分析地下部分相互作用对植物生长发育的影响。结果显示: 与单作茶相比, 间作茶塑料膜分隔方式地上部分、地下部分和总的干生物量以及根长、根表面积、根体积、分形丰度和直径为0.2-1.0 mm根的根长分别显著增加了357.1%、281.8%和345.2%以及74.3%、273.9%、244.8%、42.0%和382.4%。间作茶塑料膜分隔方式的株高渐进值比单作茶显著增加了30.9%, 尼龙网分隔方式的间作栗株高渐进值和基径渐进值比单作栗分别显著增加了21.9%和28.2%; 塑料膜分隔方式下间作茶株高达到最大增长速率的时间和间作栗的基径达到最大增长速率的时间比相应单作模式分别显著延迟了14和15天。不同处理中栗和茶的株高-基径异速生长均呈显著线性正相关关系, 且不分隔方式下间作栗和间作茶的株高-基径异速生长模型的斜率均表现为最小, 且均<1。结果表明, 栗和茶间作时, 栗地上部分通过遮阴促进茶幼苗侧根分枝数、细根根长和株高的生长来增加其干生物量累积, 但地下部分则表现为竞争作用, 且随着地下部分竞争作用的强度增加会逐渐抵消地上部分的促进作用, 最终植物种间相互作用表现为中性作用。

Growth of chestnut and tea seedlings under different root partitioning patterns

Aims The study aims to find the relationship between root interspecific interactions and root morphological characteristics, plant height and ground diameter accumulations. The effects of different division methods for the root interaction and interspecific interaction dynamics of chestnut (Castanea mollissima)/tea (Camellia sinensis) agroforestry systems were investigated, in order to provide the scientific basis for the sustainable development in chestnut/tea agroforestry systems. Methods The potting experiment set three cropping system, chestnut/tea agroforestry system, monocropping chestnut and monocropping tea as research objects, and three division methods with solid, mesh, and without root barrier under chestnut and tea roots. Plant height and ground diameter data were fitted to logistic growth models to investigate the temporal dynamics of plant growth, and the allometric relationship between plant height and ground diameter of chestnut and tea were fitted to power function. The relationships between plant growth and root interspecific interaction were analyzed in terms of the fine roots developments. Important findings The results showed that the aboveground dry mass, belowground dry mass, total plant dry mass, root length, root surface area, root volume, fractal abundance and root length of fine roots (0.2-1.0 mm) of intercropped tea with plastic separation were significantly increased by 357.1%, 281.8%, 345.2%, 74.3%, 273.9%, 244.8%, 42.0% and 382.4%, respectively, compared with those of the corresponding sole tea. The asymptotic value of plant height of the intercropped tea with plastic separation was 30.9% higher than the monoculture tea. The asymptotic value of plant height and ground diameter of the chestnut with nylon separation was 21.9% and 28.2% higher than the monoculture chestnut, respectively. In the division methods with plastic, intercropped tea significantly postponed the timing to reach the maximum daily plant height growth rates about 14 days, and intercropped chestnut markedly postponed the timing to reach the maximum daily ground diameter growth rates about 15 days compared with corresponding monocultures. There was significantly positive relationship between plant height and ground diameter of both chestnut and tea in the different treatments. In addition, the slopes of the growth equations about both intercropped chestnut and tea without separation were flatter than the other treatments, which were both lower than 1. Therefore, when tea is intercropped with chestnut trees, chestnut tree shading enhanced the growth of lateral root branches, fine root length and plant height, and facilitated the intercropped tea seedling dry mass accumulation. However, with the growing stresses of underground interspecific competition for intercropped chestnut, the aboveground interspecific facilitation was overridden gradually by the interspecific underground competition, and the final net outcome was manifested as neutral effects.