不同光质对藏川杨生长及光合特性的影响

Effect of different light quality on growth and photosynthetic characteristics of Populus szechuanica var.tibetica seedlings

【目的】研究不同光质对藏川杨幼苗生长和光合特性的影响,进一步探究藏川杨对高原地区强光环境的响应,为高光效杨树的筛选提供理论依据。【方法】以当年生藏川杨扦插苗为试材,设置白、蓝、绿3种颜色薄膜,以白膜为对照,测定分析生长及生理指标、叶绿素荧光和光合参数。【结果】蓝膜和绿膜均显著提高藏川杨幼苗株高,分别提高28.1%和38.5%,而蓝膜显著减小幼苗叶宽,降低33.3%;蓝膜显著增加幼苗叶片光合色素(31.74%)、可溶性总糖(55.57%)和蔗糖含量(78.58%),而绿膜则显著减少幼苗叶片可溶性总糖和淀粉积累;蓝膜可提高光下PSⅡ电子传递量子产率(Φ_(PSⅡ)),降低非光化学淬灭系数(NPQ),而绿膜显著降低电子传递速率(ETR)和Φ_(PSⅡ),提高NPQ;3种颜色薄膜处理下藏川杨叶片净光合速率(P_(n))的日变化曲线均呈“双峰型”,整体P_(n)数值大小顺序为蓝膜>白膜>绿膜,不同颜色薄膜处理下藏川杨叶片均在12:00时出现光合午休现象。气孔导度(G_(s))和蒸腾速率(T_(r))总体变化趋势与P_(n)类似,而胞间CO_(2)浓度(C_(i))则呈“W型”曲线;蓝膜显著提高了藏川杨叶片最大净光合速率(P_(n max))、光补偿点(LCP)、CO_(2)饱和点(CCP),绿膜降低其最大净光合速率(P_(n max))、暗呼吸速率(R_(d))和光补偿点(LCP),显著提高光呼吸速率(R_(p))、CO_(2)补偿点(CCP)。【结论】生长环境中的光质能够影响藏川杨的光合效率及生长发育。通过覆盖蓝色薄膜改善光质能增强藏川杨幼苗叶片光合色素含量、提高弱光和CO_(2)利用率、提高光合效率、增强光合产物积累、促进植株生长。

[Objective]The effects of different light qualities on the growth and photosynthetic characteristics of Populus szechuanica var.tibeti-ca seedlings were studied,and the response of P.szechuanica var.tibetica to the strong light environment in the plateau area was further ex-plored,which provided a theoretical basis for the screening of poplars with high luminous efficiency.[Method]Three color films of white,blue and green were set up with the seedlings of the P.szechuanica var.tibetica cuttings of current-year,and the white film was used as the control to determine and analyze the growth and physiological indicators,chlorophyll fluorescence and photosynthetic parameters.[Result]Both blue and green film significantly improved the plant height of P.szechuanica var.tibetica seedlings by 28.1%and 38.5%,respectively,while the leaf width of seedlings under blue film decreased significantly by 33.3%.Blue film significantly increased the contents of photosynthetic pig-ment(31.74%),soluble total sugar(55.57%)and sucrose(78.58%)in seedling leaves,while green film reduced the accumulation of soluble total sugar and starch in seedling leaves.The blue film could increase PSⅡ electron transport quantum yield underlight(Φ_(PSⅡ))and decrease non-photochemical quenching coefficient(NPQ),while green film significantly reduced electron transfer rate(ETR)and Φ_(PSⅡ) and increased NPQ.The diurnal variation curves of net photosynthetic rate(P_(n))of P.szechuanica var.tibetica leaves with the three color films were all 'bimodal type',and the order of overall P_(n) values were blue film>white film>green film,and the photosynthetic lunch break oc-curred at 12:00 with different color film treatment.The overall trend of stomatal conductance(G_(s)) and transpiration rate(T_(r))was similar to that of P_(n),while the intercellular CO_(2) concentration(C_(i))showed a 'W-shaped'curve.The blue film significantly increased the maximum net photosynthetic rate(P_(n max)),light compensation point(LCP)and CO_(2) saturation point(CCP)of P.szechuanica var.tibetica leaves,while the green film reduced the maximum net photosynthetic rate(P_(u max)),dark respiration rate(R_(d)),and lightcompensationpoint(LCP),and significantly increased the photorespiration rate(R_(p))and CO_(2) compensation point(CCP).[Conclusion]Covering the blue film could enhance the photosynthetic pigment content of P.szechuanica var.tibetica seedlings,improve the utilization rate of weak light and CO_(2) improve photosynthetic efficiency,enhance the accumulation of photosynthetic products,and promote plant growth.