土壤湿度对香樟幼苗根系生长和构型的影响

Effect of Different Soil Moisture on Root Growth and Architecture of Cinnamomum camphora

以1年生香樟(Cinnamomum camphora)幼苗为试材,设置对照组(CK)、中度干旱处理(M)、重度干旱处理(S)三个处理,比较不同土壤湿度下香樟幼苗不同时期地上部分生长和根系构型,探究香樟幼苗根系对不同土壤湿度的适应性及其耐旱机制。结果表明,中度和重度干旱处理组的香樟根系及地上部分干物质积累、根系长度、根系表面积、根系直径和根尖数均显著小于对照组(P<0.05)。同时干旱显著增加香樟幼苗的根系拓扑指数,降低香樟根的分形维数和平均分枝角度(P<0.05)。可见土壤湿度程度及处理时间显著影响香樟根系的生长及在土壤中的布局。较低土壤湿度可显著抑制根长的延长、根表面积扩大和根的增殖,且随着土壤湿度的继续降低以及处理时间延长,香樟幼苗根系的生长受到水分亏缺的抑制作用加重,根系建成成本增高的同时,根系分枝的复杂性降低,根系必须通过朝着更陡、更深的方向生长伸长来提高水分吸收效率。建议在园林绿化工程养护过程中制定科学的水分管理策略,以满足香樟生长过程中对土壤水分的需要。

The 1-year-old seedlings of Cinnamomum camphora were used as test materials, and the control group(CK), moderate drought treatment(M) and severe drought treatment(S) were set to compare above-ground growth and root configuration of the seedlings among different treatments. The results showed that the accumulation of dry matter, root length, root surface area, root diameter and number of root tips of C. camphora in the moderate and severe drought treatment groups were significantly smaller than those of control group(P<0.05). Drought also significantly increased the root topology index and reduced the fractal dimension and mean branching angle of roots in C. camphora seedlings(P<0.05). The degree of soil moisture and the duration of treatment significantly affected the growth of C. camphora roots and their placement in the soil. Lower soil moisture treatments significantly inhibited root length extension, root surface area expansion and root proliferation, and as soil moisture levels continued to decrease and treatment times increased, the inhibition of C. camphora seedling root growth by water deficit increased and root establishment costs increased while root branching complexity decreased and root systems had to grow and elongate in steeper, deeper directions to improve water uptake. The root system must improve water uptake efficiency by elongating in a steeper and deeper direction. It was recommended that scientific water management strategies should be developed during the maintenance of landscaping projects to meet the needs of soil moisture during the seedling growth of C. camphora.