3个与杉木混植木荷种源幼苗对光照响应的差异

目的]探寻不同木荷种源混交林生产力差异的光合机制。[方法]以福建建瓯、江西信丰和浙江龙泉3个木荷代表性种源1年生和2年生幼苗为试验材料,在与杉木混植条件下,设置100%(L0)、50%(L1)和25%(L2)3种光照的光环境,研究3个木荷种源幼苗的生长性状、光合生理及叶绿素荧光特性等对不同光照响应的差异。[结果]1年生和2年生木荷幼苗的苗高、地径和干质量均表现出显著的种源差异,福建建瓯种源幼苗生长优于浙江龙泉种源和江西信丰种源。随着遮阳强度的提高,1年生和2年生2个发育阶段,福建建瓯种源幼苗比叶面积和叶绿素含量等明显增加,叶绿素a/b值、光饱和点、暗呼吸速率和Fo值等均显著降低,表现出较高的形态和生理塑性;相同遮阳处理下福建建瓯种源幼苗总叶面积、叶绿素含量和Fv/Fm值等指标显著高于浙江龙泉种源和江西信丰种源,而叶绿素a/b值、光饱和点、光补偿点和暗呼吸速率则明显低于两种源;长期遮阳和混植状态下福建建瓯种源幼苗可通过较高的生物量分配塑性,增加根系在土壤中分布来响应邻株竞争,进而促进整株干物质的积累;各光环境下,3个木荷种源2年生幼苗Fo、Fm、Fv/Fm和Fv/Fo等叶绿素荧光参数均较1年生幼苗明显升高,但各光环境间差异不显著。[结论]不同木荷种源混交林生产力差异与其对光照的塑性反应能力有关,并随幼苗年龄而变化。

Response of Seedlings of Three Schima superba Provenances to Different Light Environments When Mixed Planting with Cunninghamia lanceolata

[Objective] To explore the photosynthetic mechanism for productivity of Schima superba mixed planting.[Method] This study took one year and two years old seedlings of three S. superba provenances coming from Jian''ou of Fujian Province, Xinfeng of Jiangxi Province and Longquan of Zhejiang Province, which were mix-planted with Cunninghamia lanceolata, as the subjects. The response and laws of growth traits, photosynthetic physiology and chlorophyll fluorescence characteristics of the seedlings to light circumstances set as 100% (L0), 50% (L1) and 25% (L2) of light transmittance were studied.[Result] The results showed that the dry matter quality for one year and two years old S. superba seedlings was apparently different with varied light environments. The seedlings of Longquan provenance were superior than that of Xinfeng provenance, which may be related to the strong ability of searching light. During two development stages, the leaf area and chlorophyll content of the seedlings of Jian''ou provenance significantly increased after shading, while the chlorophyll a/b value, the light saturation point, the dark respiration rate and the minimal fluorescence (Fo) value dramatically decreased, indicating that by increasing the leaf area and the chlorophyll content, the seedlings of Jian''ou provenance changed the chlorophyll composition and photosynthetic physiological characteristics, and enhanced the ability of low light capture and transformation, which also showing higher morphology and physiological plasticity. The total leaf area, chlorophyll content and variable fluorescence/maximal fluorescence (Fv/Fm) index of Jian''ou provenance were significantly higher than those in Longquan provenance and Xinfeng provenance under same condition, but the chlorophyll a/b value, light saturation point, light compensation point and dark respiration rate were significantly lower than that of the latter two provenances, which indicated that S. superba of Jian''ou provenance was more shade tolerance, and could be adapted to a wider range of light. Unlike Longquan provenance and Xinfeng provenances, the root-shoot ratio of 2-year-old seedlings of Jian''ou provenance increased significantly after one year''s shading, might mean that long-term shading and mixed planting could also be distributed by high biomass redistribution ability. And, increasing distribution of root biomass could enhance the competition with neighbors and promote the accumulation of biomass of the whole seedling at last. The chlorophyll fluorescence parameters of Fo, Fm, Fv/Fm and Fv/Fo were obviously higher for 2 years seedlings than that of 1 year under different light conditions, While, the differences between light treatments were not significant.[Conclusion] The productivity of S. superba mixed with C. lanceolata is related to the plasticity to different light environment, and varies with seedling age changing.