光合有效辐射对芒萁光合、荧光和光合诱导特征的影响

The Effect of Photosynthetically Active Radiation on the Photosynthetic,Fluorescence,and Photosynthesis-Induced Characteristics of Dicranopteris dichotoma

为探明光合有效辐射对芒萁(Dicranopteris dichotoma)生长的影响,研究了全光照、中等强度光照(透光率36%)和弱光照(透光率5%)3种处理对芒萁光合、叶绿素荧光和光合诱导特征的影响。结果表明:(1)全光照处理芒萁生物量最小,羽叶长和宽最小;中强度光照处理芒萁生物量最大,分株数最多;弱光照处理芒萁羽叶长和宽最大,且地上部、下部干质量比最高,约为全光照处理和中强度光照处理的1.9倍。(2)中强度光照处理芒萁最大净光合速率、光饱和点净光合速率、表观量子效率最高,光补偿点净光合速率和暗呼吸速率较低;全光照处理芒萁最大净光合速率和表观量子效率最低,且光系统Ⅱ的K点相对可变荧光、J点相对可变荧光显著高于中强度光照和弱光照处理,综合性能参数(PI_(ABS))显著低于中强度光照和弱光照处理,产生了光抑制现象;弱光照处理最大净光合速率与全光照处理相当,综合性能指数显著高于中强度光照和全光照处理。(3)光合诱导中,中强度光照处理芒萁达到50%和90%最大净光合速率的时间仅为1.10和4.99 min,全光照处理为2.07和6.98 min,弱光照处理为3.93和12.41 min。而且中强度光照处理诱导状态持续时间最长,全光照处理次之,弱光照处理最短。全光照环境对芒萁生长产生了光抑制,弱光环境降低了芒萁对光斑的利用能力,中等强度光照芒萁光合效率最高,光斑利用能力最强,营养和生殖生长状况均为最佳。

To investigate the impact of photosynthetically active radiation on the growth of Dicranopteris dichotoma,three treatments(full sunlight,moderate light intensity(transmittance 36%),and weak light intensity(transmittance 5%))were studied for their effects on the photosynthetic,chlorophyll fluorescence,and photosynthesis-induced characteristics of D.dichotoma.The results showed that:(1)Under full sunlight treatment,D.dichotoma had the lowest biomass,and the smallest dimensions of frond length and width.Under moderate light intensity treatment,D.dichotoma exhibited the highest biomass and the most number of offshoots.Under weak light intensity treatment,the length and width of the frond of D.dichotoma were the largest,and the highest aboveground to belowground dry weight ratio,approximately 1.9 times that of full sunlight and moderate light intensity treatments.(2)Under moderate light intensity treatment,D.dichotoma showed the highest net photosynthetic rate,light saturation point net photosynthetic rate,and apparent quantum efficiency,with lower light compensation point net photosynthetic rate and dark respiration rate.Under full sunlight treatment,D.dichotoma exhibited the lowest net photosynthetic rate and apparent quantum efficiency,with significantly higher relative variable fluorescence at K point and J point of Photosystem Ⅱ compared to moderate and weak light intensity treatments,and significantly lower comprehensive performance index(PI_(ABS)),resulting in photoinhibition.Under weak light intensity treatment,the maximum net photosynthetic rate was comparable to full sunlight treatment,with the comprehensive performance index significantly higher than moderate light intensity and full sunlight treatments.(3)During the induction of photosynthesis,D.dichotoma under moderate light intensity treatment took only 1.10 and 4.99 minutes to reach 50% and 90% of the maximum net photosynthetic rate,whereas full sunlight treatment took 2.07 and 6.98 minutes,and weak light intensity treatment took 3.93 and 12.41 minutes.Additionally,the induction state duration was longest under moderate light intensity treatment,followed by full sunlight treatment,and shortest under weak light intensity treatment.Full sunlight conditions inhibited the growth of D.dichotoma,while weak light environments decreased D.dichotoma’s ability to utilize light spots.D.dichotoma exhibited the highest photosynthetic efficiency and light spot utilization ability under moderate light intensity,resulting in optimal nutritional and reproductive growth conditions.