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以杂交泡桐毛白33(即TF33)及其回交一代(BC1(194)和BC1(192))为材料,通过人工模拟旷地、林窗和林下3种光环境(分别为全光照L0、50%全光照L1、25%全光照L2),比较了不同光强下泡桐回交一代及其亲本TF33叶片的光合能力和叶绿素荧光特性的差异。结果显示:(1)遮荫后杂交泡桐净光合速率(Pn)日变化曲线由“双峰”型变为“单峰”型,日平均Pn随遮荫程度增加显著降低(P<0.05)。L0条件下,BC1(194)和BC1(192)的日平均Pn未表现出杂种优势;L1条件下,BC1(192)和BC1(194)的日平均Pn杂种优势率(RH)分别为2.23%和3.67%;L2条件下,BC1(192)的日平均Pn高于TF33,但差异不显著,BC1(194)则表现为杂种劣势。(2)L0条件下,TF33的最大净光合速率(Pmax)和光饱和点(LSP)最大,光补偿点(LCP)和暗呼吸速率(Rd)最小;L1条件下,BC1(192)的Pmax、LSP和AQY最大,LCP和Rd最小;L2条件下,虽然BC1(194)和BC1(192)的Pmax低于TF33,但其LCP和Rd值也低于TF33。(3)L0条件下,TF33、BC1(194)和BC1(192)各荧光参数差异不显著;L1条件下,3个无性系的q P和q N差异显著,BC1(192)的热耗散最弱,光合能力最强;L2条件下,BC1(192)和TF33的q P差异不显著,BC1(194)与TF33差异显著,BC1(192)的Fv/Fm、F0和ETR与TF33、BC1(194)差异显著(P<0.05)。结果表明,TF33、BC1(194)和BC1(192)虽均对弱光有一定的调节适应机制,但在全光照下生长最为适宜,遮荫使植株的光合能力显著降低,光照不足成为其生长的决定性限制因子。在低光照(L1)条件下,BC1(194)和BC1(192)较其亲本TF33有光合优势。
The results showed that there was no significant difference in the photosynthetic rate between Paulownia fulva 33 (TF33) and its backcross (BC1 (194) and BC1 (192) , 50% full light L1 and 25% full light L2). The differences in photosynthetic capacity and chlorophyll fluorescence of the leaves of paulownia paulownia F1 generation and their parents TF33 under different light intensities were compared. The results showed that: (1) The daily net photosynthetic rate (Pn) of hybrid Paulownia changed from “bimodal ” to “unimodal ” type after shading. The daily average Pn decreased significantly with the increase of shade (P <0.05). The daily average Pn of BC1 (194) and BC1 (192) showed no heterosis under L0 conditions. The daily mean Pn heterosis (RH) of BC1 (192) and BC1 (194) And 3.67%, respectively. Under the condition of L2, the average daily average Pn of BC1 (192) was higher than that of TF33, but the difference was not significant. BC1 (194) showed heterosis. (2) Under the condition of L0, the maximal Pmax and LSP of TF33 were the largest, while LCP and Rd were the least. Under L1, Pmax, LSP and AQY were the largest while LCP and Rd were the lowest. Under L2, Pmax of BC1 (194) and BC1 (192) was lower than that of TF33, but LCP and Rd were lower than TF33. (3) The fluorescence parameters of TF33, BC1 (194) and BC1 (192) were not significantly different under L0 conditions; the differences of q P and q N among the three clones were significant under the condition of L1, the heat dissipation of BC1 (192) (192) and TF33 were significantly different between BC1 (192) and TF33. The differences of BC1 (194) and TF33 between BC1 (192) and TF33 were not significant (194) significant difference (P <0.05). The results showed that although TF33, BC1 (194) and BC1 (192) all had some regulation and adaptability to low light, their growth was most suitable under all light conditions. Shading reduced the photosynthetic capacity of plants significantly, The decisive limiting factor. Under low light (L1) conditions, BC1 (194) and BC1 (192) had photosynthetic advantages over their parent TF33.