遮光与水分胁迫对盆栽芒萁光合与叶绿素荧光参数的影响

Effects of shading and drought stress on photosynthetic and chlorophyll fluorescence parameters of potted Dicranopteris dichotoma

【目的】研究光合有效辐射与土壤水分变化对芒萁Dicranopteris dichotoma光响应进程及原初光化学反应的影响,分析芒萁单优层片发育成因。【方法】设置不同光合有效辐射[轻度遮光(透光率为35.96%,L1),中度遮光(13.00%, L2)和高度遮光(4.75%, L3)]与土壤水分[充足水分(土壤相对含水量为75%~80%, W1),中度干旱(50%~55%,W2),重度干旱(25%~30%,W3)]双因素控制试验,并以全光处理为对照,比较分析盆栽芒萁光合特征参数和叶绿素荧光诱导动力学参数的变化特征。【结果】①轻度遮光条件下,重度干旱显著降低了芒萁的净光合速率(Pn)、表观量子效率(YAQ)和最大净光合速率(Pmax),轻度遮光条件下充足水分(W1)和中度干旱(W2)的Pn大约比重度干旱(W3)和对照(ck)高34.4%~69.2%;②中度遮光和高度遮光条件下,各浇水处理间芒萁的Pn大致相近且略高于ck,光补偿点(LCP)和暗呼吸速率(Rd)差异不显著(P>0.05),增加遮光强度能够缓解水分亏缺对芒萁的光合特征参数的负面影响;③在相同水分处理条件下,随着遮光强度增加,芒萁的荧光参数呈现先增加后下降的变化特征。④轻度和中度遮光下重度干旱降低了芒萁的光合机构能力,高度遮光时,随着土壤水分的降低,盆栽芒萁叶片的电子传递效率(ψO)、电子传递量子产额(φEo)、能量流参数和光合性能指数(PIABS)均出现上升趋势,说明弱光环境下芒萁表现出明显的抗旱性。⑤遮光和干旱处理未对芒萁的PIABS和综合性能指数(PItotal)产生显著的抑制作用,说明芒萁的PSⅡ没有受到严重损害。【结论】因此,中度遮光+充足水分组合处理有利于盆栽芒萁积累光合产物,中度遮光与中度干旱下盆栽芒萁拥有最高的PSⅡ活性,盆栽芒萁对遮光和土壤水分变化的环境表现出较强的适应性。

[Objective] To analyze the causes for the development of Dicranopteris dichotoma monodominant synusium, photoresponse process and primary photochemical reaction in D. dichotoma were studied. [Method]Different levels of light intensity(slight shade, L1, medium shade, L2 and heavy shade, L3) and soil moisture(sufficient moisture, W1, moderate drought, W2 and severe drought, W3) were set, compared with all light treatment, and the change characteristics of photosynthetic parameters and chlorophyll fluorescence induction kinetic parameters of potted D. dichotoma were analyzed. [Result](1) Under slight shading, severe drought significantly reduced Pn, YAQ and Pmax of D. dichotoma, and the Pn of sufficient moisture and moderate water control was approximately 34.4%-69.2% higher than that of ck;(2) Under medium and heavy shade, Pnbetween three water control treatments was similar and slightly higher than that of ck, and there was no significant difference in LCP and Rd(P>0.05), which indicated that the increase of shade degree could alleviate the negative effect of water deficit on the photosynthetic parameters of D. dichotoma;(3) Under the same soil moisture, the fluorescence parameters showed a change characteristic of first increasing and then decreasing with the increase of shade degree;(4) Severe drought stress reduced the photosynthetic mechanism capacity of D. dichotoma under slight and medium shade;under heavy shade, the ψO, φEo, energy flow parameters and PIABS growed upward with the decrease of soil moisture, which showed that D. dichotoma had obvious drought resistance in low light environment;(5) Shade and drought did not significantly inhibit the PIABS and PItotal,indicating that PSⅡ of D. dichotoma was not seriously damaged. [Conclusion] It is considered that the combination of medium shade and sufficient moisture is more conducive for potted D. dichotoma to accumulate photosynthate. Under medium shade and moderate drought, potted D. dichotoma has the highest activity of PSⅡ, with a strong adaptability showed to the changes of shade environment and soil moisture.