干旱对杉木幼苗根系构型及非结构性碳水化合物的影响

通过比较不同时期不同强度干旱胁迫下杉木1年生盆栽苗地上部分生长、根系构型以及根系中非结构性碳水化合物含量（TNC）的变化,并分析各指标之间的相关性,探究杉木根系在干旱胁迫下的适应性策略以及抗旱生理机制,以期为杉木造林生产和水分管理提供科学依据和技术指导。结果表明：随着干旱程度的加强,杉木幼苗地上部分干重（SDW）、根干重（RDW）、根长（RL）、根表面积（SA）、根体积（RV）、根尖数（RT）、根系分支角度（Angle）、分形维数（FD）逐渐减小,根冠比（R/T）逐渐增大,根系拓扑指数（TI）、根系平均直径（RD）先增大后减小,比根长（SRL）先减小后增大。而根系连接长度（LL）、TNC、糖淀比在不同时期表现出不同的趋势。连接长度随着干旱胁迫的加强在30 d和60 d时表现出逐渐增加趋势而在90 d时则表现出先减小后增大的趋势。TNC在30 d和60 d时先增大后减小,但90 d时,呈逐渐下降的趋势。糖淀比随着干旱胁迫的加强在30 d和60 d时表现出先增加后减小趋势,90 d时,表现为先减小后增大。干旱胁迫显著影响根系在不同径级的分布长度,且随着胁迫时间的延长不断变化。杉木地上部分生长与根系生长指标（RL、SA、RV、RT、RDW）以及根系构型指标（Angle、FD）之间存在显著的正相关（P < 0.01）,根系平均直径与TNC存在显著的正相关（P < 0.05）。总之,杉木通过增加根系光合产物的积累、提高根系建成成本,增加有限成本下根系的复杂程度和延伸范围,降低根系分支角度,使根系"更陡更深"来适应不同强度的干旱胁迫。

Effects of drought on root architecture and non-structural carbohydrate of Cunninghamia lanceolata

To provide a scientific basis and technical guidance for afforestation and water management for Cunninghamia lanceolata,this study resistance the adaptability strategies of C. lanceolata roots under drought stress and the physiological mechanisms of drought resistance. The growth of the above-ground part,root architecture and non-structural carbohydrate contents(TNC)in the roots of one-year-old potted seedlings was compared under different levels of drought stress for different periods,and the relationships between the indexes was analyzed.The results showed that shoot dry weight(SDW),root dry weight(RDW),root length(RL),root surface area(SA),root volume(RV),root tip number(RT),fractal dimension(FD)of C. lanceolata seedlings decreased with increasing drought. R/T gradually increased,and Root topological index(TI)and root diameter(RD)initially increased and then decreased. The Specific root length(SRL)initially decreased and then increased,whereas the average link length(LL),TNC,and sugar starch ratio showed different trends in different periods. The LL increased gradually with the increase of drought stress on d 30 and 60,but on d 90 it decreased initially and then increased.TNC increased initially and then decreased on the d 30 and d 60,but gradually decreased on d 90. The sugar starch ratio increased initially and then decreased with increased of drought stress on the d 30 and 60. On d 90,it increased initially and then decreased. Drought stress significantly affected the root length distribution at different diameters,and changed with increasing stress duration.There was a significant positive correlation between the above-ground part growth and root growth index (RL,SA,RV,RT,RDW),root architecture index (Root branch angle,FD) of C. lanceolata(P < 0.01),and there was a significant positive correlation between root mean diameter and TNC(P < 0.05). In conclusion,C. lanceolata increased the photosynthate accumulation in roots,the cost of root construction,complexity and extension of the root system under limited cost,and reduced the angle of root branching,resulting in a "steeper and deeper" root system to adapt to drought stress with different intensities.