大花紫薇幼苗对水分胁迫及解除的生长响应

摘要:

目的

分析不同水分处理对抗性树种大花紫薇Lagerstroemia speciosa生长的影响，探究大花紫薇形态性状的响应机制，为抗性园林树种的选择及水分管理提供理论依据。

方法

以大花紫薇的1年生幼苗为材料，设置干旱(DR)、水淹(WL)、水淹−干旱交叉(WD)和对照(正常浇水，CK) 4种水分处理，开展30 d水分胁迫试验，随后解除水分胁迫，并维持DR、WL、WD处理组植株的土壤水分在CK水平，进行为期30 d的恢复生长，测定水分胁迫及解除后植株的叶性状、根系性状和生物量指标。

结果

DR、WD胁迫终期和WL恢复终期的总叶面积相较CK显著下降；3种水分胁迫处理的叶组织密度在胁迫终期相较CK显著上升，比叶面积在恢复终期显著下降。胁迫终期时，WL和WD处理提升了细根根长占比和细根表面积占比；恢复终期时，DR、WL、WD处理的细根表面积占比分别比CK升高了9.59%、12.42%、13.57%；胁迫终期和恢复终期时，WL处理的比根长和比根面积显著高于CK。胁迫终期时，3种水分胁迫下的植株增加了对茎的生物量分配，且WL处理植株生长的不定根占总根系生物量的26.95%；DR胁迫终期和恢复终期的根系生物量分配显著升高，根冠比分别相比各自CK提升了40.93%和70.06%。相关性分析表明，叶性状间、根系性状间分别存在权衡关系；根长、根表面积与叶组织密度呈显著正相关。

结论

大花紫薇叶−根系性状间存在一定的相关性；短期的水分胁迫对大花紫薇幼苗根系生长具促进作用，使其更好地适应城市园林绿地复杂多变的水环境。

Abstract:

Objective

To analyze the effects of different water treatments on the growth of resistant tree species Lagerstroemia speciosa, explore the response mechanism of morphological traits of L. speciosa, and provide a theoretical basis for the selection and water management of resistant landscape tree species.

Method

Using the one-year-old seedlings of L. speciosa as materials, a 30-day water stress experiment was conducted by setting up four types of water treatments, drought (DR), waterlogging (WL), waterlogging-drought alternating (WD), and control (normal water supply, CK). Subsequently, the water stress was relieved and the soil moisture in the DR, WL and WD treatments was maintained at the CK level for a 30-day recovery period of growth. The leaf traits, root traits and biomass indicators of plants after water stress and relief were measured.

Result

Total leaf areas of L. speciosa significantly decreased at the end of DR, WD stress and at the end of recovery after WL stress compared with CK. Leaf tissue densities of the three water stress treatments were significantly higher at the end of stress compared to CK, and specific leaf areas were significantly lower at the end of recovery. Compared with CK, the WL and WD treatments increased the rates of fine root length and the rates of fine root surface area at the end of stress. At the end of recovery, the rates of fine root surface area were higher in the DR, WL and WD treatments by 9.59%, 12.42%, and 13.57%, respectively, compared to CK. At the end of stress and recovery, the specific root length and specific root surface area in WL treatment was significantly higher compared to CK. At the end of stress, plants under the three water stress treatments increased biomass allocations to stems, and WL treatment plants grew adventitious roots that accounted for 26.95% of total root biomass. Under DR treatment, the root biomass allocation at the end of stress and recovery significantly increased, and the root-shoot ratio increased by 40.93% and 70.06% respectively, compared to their own CK. Correlation analysis showed that there was a trade-off relationship among leaf traits and root traits respectively. Root length, root surface area, and leaf tissue density were significantly positively correlated, and root growth had a positive effect on the leaf tissue density.

Conclusion

There is a certain correlation between leaf and root traits. Short term water stress can promote the root growth of L. speciosa seedlings, making them better adapt to the complex and varied water environment of urban landscaping and green spaces.

图  1   水分胁迫对根系性状的影响

CK：对照，DR：干旱，WL：水淹，WD：水淹−干旱交叉；R0为水分胁迫解除的胁迫终期和恢复期起点，R15和R30分别为水分胁迫解除后恢复期的第15、30天，其中R30为恢复终期；各图中，相同时间的不同小写字母表示处理间差异显著(P<0.05，Duncan’s法)

Figure  1.   The effects of water stress on the root traits

CK: Control, DR: Drought, WL: Waterlogging, WD: Waterlogging-drought alternating; R0 represents the ending of stress and the starting of recovery period after water stress is relieved, while R15 and R30 represent the 15th and 30th days of recovery period after water stress is relieved, with R30 being the ending of recovery period; In each figure, different lowercase letters of the same time indicate significant differences among treatments (P<0.05, Duncan’s method)

图  2   水分胁迫对总生物量和根冠比的影响

CK：对照，DR：干旱，WL：水淹，WD：水淹−干旱交叉；各图中，相同指标的不同小写字母表示处理间差异显著(P<0.05，Duncan’s法)

Figure  2.   Effects of water stress on total biomass and root-shoot ratio

CK: Control, DR: Drought, WL: Waterlogging, WD: Waterlogging-drought alternating; In each figure, different lowercase letters of the same index indicate significant differences among treatments (P<0.05, Duncan’s method)

图  3   水分胁迫对生物量分配的影响

CK：对照，DR：干旱，WL：水淹，WD：水淹−干旱交叉；各图中，相同指标的不同小写字母表示处理间差异显著(P<0.05，Duncan’s法)

Figure  3.   Effects of water stress on biomass allocation

CK: Control, DR: Drought, WL: Waterlogging, WD: Waterlogging-drought alternating; In each figure, different lowercase letters of the same index indicate significant differences among treatments (P<0.05, Duncan’s method)

图  4   叶和根系性状指标相关性分析热图

TLA：总叶面积，LT：叶厚度，SLA：比叶面积，LTD：叶组织密度，RL：根长，RSA：根表面积，SRL：比根长，SRSA：比根面积，RTD：根组织密度；“*”和“**”分别表示在P < 0.05和P < 0.01水平显著相关(Pearson法)

Figure  4.   Heat map of correlation analysis among leaf and root traits

TLA: Total leaf area, LT: Leaf thickness, SLA: Specific leaf area, LTD: Leaf tissue density, RL: Root length, RSA: Root surface area, SRL: Specific root length, SRSA: Specific root surface area, RTD: Root tissue density; “*” and “**” indicate significant correlations at P<0.05 and P<0.01 levels respectively (Pearson method)

表  1   水分胁迫对叶性状的影响1)

Table  1   The effects of water stress on the leaf traits

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