强光胁迫对濒危植物金花茶幼苗生长和叶绿素荧光参数的影响

Effect of Strong Light Stress on the Growth,Biomass and Chlorophyll Fluorescence Parameters in Seedlings of Endangered Plant Camellia nitidissima

以当年生盆栽金花茶实生苗为材料,研究不同程度的强光胁迫(25%、50%和100%自然光强,以8%自然光强为对照)对其生长、生物量、叶片光合色素含量、叶绿素荧光参数的影响。结果表明:在不同程度的强光胁迫下,金花茶幼苗的生长均受到抑制,随着胁迫程度的增强,金花茶叶片颜色由深绿变为浅绿、黄绿色,叶片灼伤愈来愈严重;植株抽稍时间推迟,抽稍后长出的新叶长势较差;幼苗死亡率越来越高。幼苗根生物量、茎生物量、叶生物量和总生物量均随胁迫程度的升高而显著降低,强光胁迫对叶生物量的影响最大,根生物量次之,对茎生物量的影响最小。随着胁迫程度的增强,叶片叶绿素总量(Chl)、叶绿素a(Chla)、叶绿素b(Chlb)含量均显著降低,Chla/Chlb和Car/Chl显著升高。叶绿素荧光参数Fo、Fm、Fv、Fv/Fm、Fv/Fo均随胁迫程度的升高降低,强光胁迫使PSⅡ受到了伤害,光合作用原初反应过程受抑制,光合电子传递受到影响,从而抑制植株的正常生长。

Camellia nitidissima is shade-tolerant and has a limited photosynthetic potential of acclimating high light. The effects of different shading levels （8%, 25%, 50% and 100% of full sunlight） on the growth, bio- mass, chlorophyll fluorescence parameters of C. nitidissima seedlings were examined in order to know the growth and physiological responses of C. nitidissima to strong light. The growth of C. nitidissima seedlings were inhibited under different strong light stress. As the strong light stress was enhanced, the color of C. nitidissima seedlings leaves turned into light green and yellow green from dark green, leaf burning was getting worse, time of shooting was delayed and the shoots grew poor, the death rate increased. The biomass of root, stem, leaf and total plant significantly decreased with the strengthened stress. The strong light stress had the most influence on leaf bio- mass, followed by root biomass, and then the stem biomass. With the increasing strong light stress, the contents of total chlorophyll （Chl）, chlorophyll a （Chla） and chlorophyll b （Chlb） in leaves of C. nitidissima seedlings significantly decreased, while Chla/Chlb and Car/Chl increased. The chlorophyll fluorescence parameters Fo, Fm, Fv, Fv/Fo, Fv/Fm all decreased under strong light stress, which indicated that with the increasing of strong light stress, the reaction center of PS 11 was destroyed, photosynthetic electron transform capability was weakened and photosynthesis was restrained.