遮阴和施氮对金荞麦生长和光合荧光特性的影响

Effects of shading levels and nitrogen application on the growth and photosynthetic fluorescence characteristics of Fagopyrumdibotrys

[目的]揭示遮阴和氮肥对金荞麦生长和叶绿素荧光参数的调控效应,探明适宜金荞麦生长的最佳光氮条件。[方法]以牧草金荞麦幼苗为研究对象,设置透光度100%(CK处理,不遮阴)、60%(L1处理,轻度遮阴)、10%(L2处理,重度遮阴)3个光处理中设不施氮(N0,0g/盆)和施氮(N1,1g/盆)处理。[结果]随光强减弱,金荞麦叶长、叶宽、叶柄长、根长及叶、茎枝、地上生物量呈“增大-减小”趋势,叶面积在轻度遮阴下显著增大(P<0.05),株高、叶绿素含量在重度遮阴下明显增高(P<0.05),qN(非光化学淬灭系数)显著升高(P<0.05),而qP(光化学淬灭系数)则明显降低(P<0.05);增施氮肥,叶长、叶面积、叶绿素含量比单一光强下显著增加;不同遮阴度及氮肥的交互作用下,轻度遮阴下增施氮肥,金荞麦的叶长、株高、YⅡ(实际光量子产量)最大,重度遮阴下增施氮肥抑制茎、叶生物量积累。[结论]光照减弱,金荞麦叶片非辐射能量耗散显著增加,用于光化学反应的光能的份额则明显减少,进而保护光合结构。轻度遮阴促进金荞麦生长及生物量积累,而重度遮阴抑制金荞麦生长及生物量积累;轻度遮阴下增施氮肥有利于增加金荞麦叶面积,进而增加光合面积,提高对光能的捕获能力,促进光合有机物积累。

[Objectives] The purposes of present study were to reveal the effects of different shading levels and nitrogen fertilizer on the growth and chlorophyll fluorescence parameters of Fagopyrumdibotrys and to determine the optimal photo-nitrogen conditions for the growth of F.dibotrys .[Methods] The seedlings of F. dibotrys were employed asthe research materials.Three shading levels including 100% transmittance (CK,no shading),60% shading (L1),and 90% shading (L2) were selected as the major effect factors.Two fertilizer treatments,no nitrogen application (N0) and nitrogen application (N1,1g / pot) were used as second effect factor.The variations of photosynthetic fluorescence characteristics were determined,and the interaction between two factors were analyzed by two-way ANOVA.[Results] With the decrease of light intensity,the leaf length and width,petiole length,root length,and the biomass of leaves,stems and above-ground parts of F.dibotrys showed an increase-peak-decrease trend;The leaf area was increased significantly in L1 treatment.In L2 treatment,plant height,chlorophyll content,and qN(non-photochemical quenching coefficient) were significantly enhanced,while qP (photochemical quenching coefficient) was decreased dramatically.Leaf length,leaf area,and chlorophyll content in all treatments positively and significantly reacted to the application of nitrogen fertilizer comparing to the light intensity only treatments.When two factors co-existed,leaf length,plant height,and YII (actual light quantum yield) of F.dibotrys were greater than that of other treatments,while the biomass accumulation of both stems and leaves in L3+fertilizer treatment were inhibited.[Conclusion] When the light intensity was weakened,the non-radiative energy dissipation of the golden buckwheat leaves was significantly increased,and the propotion of the light energy used for the photochemical reaction was dramatically reduced,therefore the photosynthetic structures were protected.Mild shading promoted the growth and biomass accumulation of F.dibotrys,while they were inhibited by severe shading;Adding nitrogen fertilizer under mild shading was beneficial to the increase of leaf area of F.dibotrys,thereby increasing photosynthetic area,enhancing the ability capture light,and promoting the accumulation of photosynthetic organic matter.