两种杂交杨品系光合系统Ⅱ叶绿素荧光特征

Chlorophyll fluorescence characteristics of photosystem Ⅱ of two cultivated poplars seedlings

比较研究伊犁地区两种典型杨树苗大叶杨(大叶钻天杨P.balsanifera Linn(Da))和伊犁杨5号(P.euramerieana cv(I-467))对太阳辐射光能的利用和耗散特性。光照条件下光合系统Ⅱ反应中心(PSⅡ)的最大光化学效率(Fv′/Fm′)、实际光化学效率(ΦPSⅡ)和光合功能的相对限制(L(PDF))的分析表明,高的光合有效辐射强度(PAR)会导致光合作用的光抑制,但并不造成PSⅡ反应中心的不可逆破坏。淬灭分析表明,Da的光化学淬灭系数(qP)大于I-467,非光化学淬灭(NPQ)则相反(p<0.05)。Da的NPQ显著小于I-467的,意味着I-467将PSⅡ反应中心吸收的过剩光能以热耗散等非光化学过程消耗的能力大于Da,因而相应降低了用于qP的份额。两种杨树的NPQ日变化趋势很相似;Fv′/Fm′和ΦPSⅡ的日变化趋势相似。Da的PSⅡ天线色素吸收光能中分配于光化学反应平均的相对份额(P)高于I-467,在较低的PAR环境中Da比I-467能更好的利用光能;Da用于天线热能耗散的相对份额(D)则小于I-467,两者具有极显著差异(p<0.01)。Da的ΦPSⅡ比I-467大,是因为PSⅡ天线色素吸收的光能中分配于P或光化学淬灭的比例较大,而分配于D或非光化学过程的比例较小的缘故,反应中心的ΦPSⅡ也较Da小。在有效的利用光能方面,Da比I-467更适宜在新疆伊犁地区大面积推广栽植。

Our objective is to determine solar utilization and dissipation characteristics in two introducing and widely planted poplar, P. balsanifera Linn （Da） and P. euramerieana ev （Ⅰ-467） in the Ili Autonomous Prefecture characterized by poplar high-production and high solar radiation. We used a portable LCF （ Li-6400, LI-COR, US） to explore the characteristics of two poplar seedlings utilization, dissipation of photochemical quenching and non-photochemical quenching. Strong solar radiation could cause the photoinhibition of photosynthesis, but this constitutes reversible destruction to PS Ⅱ reaction center in both plants. The study indicates there are the relatively lower net photosynthesis （Pn） and photochemical quenching （qP） in Ⅰ-467 than in Da and the higher NPQ, in Ⅰ-467. The NPQ is higher forⅠ-467 compared to Da. so actual photochemistry efficiency ФPS Ⅱ was higher in Da than Chlorophyll fluorescence Quenching analysis indicated that Da could use more solar energy utilized to qP than Ⅰ-467, but Ⅰ-467 could dissipate more excess excitation energy in PS Ⅱantennae through non-photochemistry progress than Da, as the fraction of energy utilized in photochemistry decreasing. Diurnal variations of Fv＇/Fm＇ and ФPS Ⅱ were similar in the two plants, as NPQ was the main component in nonphotochemical quenching, and both were higher in 1-467 than Da （p 〈 0.05）. The fraction of light energy absorbed in PS H antennae was lower in Ⅰ- 467 than in Da （p 〈 0.01 ）, but the fraction that was dissipated thermally （D） was significantly higher in Ⅰ-467 than in Da （p 〈 0.01 ） under the low radiation. The excess excitation after midday （Excess） was declined in the two plant seedlings. Da is more adaptive than Ⅰ-467 to plant in Ili Autonomous Prefecture for solar energy utilization.