不同光照条件下大花蕙兰净光合速率和叶绿素荧光参数的日变化

)Diurnal changes of net photosynthetic rate and chlorophyll fluorescence parameters of Cymbidium hybrid ‘nobuko’ under different light intensities

以大花蕙兰红霞"为试验材料,研究不同光照强度(全光照、36%光照和18%光照)下,不同苗龄大花蕙兰净光合速率和叶绿素荧光参数的日变化.结果表明:在3种光强下,一年生大花蕙兰净光合速率的日变化呈双峰曲线;在36%光照和18%光照下,二年生大花蕙兰净光合速率的日变化呈单峰曲线;无论何种光强和苗龄,大花蕙兰的净光合速率都较低.对叶绿素荧光参数的研究表明:在36%光照下,一、二年生大花蕙兰光系统具有较高的活性;光强超过850μmol?m-2?s-1时,大花蕙兰叶片发生光抑制,但当光合有效辐射(PAR)下降时,叶片的光合能力恢复;在364～400μmol?m-2?s-1光强下,大花蕙兰叶片叶绿素荧光参数维持在较高水平,有较好的光响应能力.

Diurnal changes of net photosynthetic rate and chlorophyll fluorescence parameters in one-year old and two-year old Cymbidium hybrid ＇ nobuko＇ plants were investigated under three light intensities （full light intensity, 36% of full light intensity and 18% of full light intensity）. The results show that diurnal changes of net photosynthetic rate of one-year old C. hybrid were displayed two-peak curve under three light intensities. Under 36 % of full light intensity and 18 % of full light intensity, diurnal changes of net photosynthetic rate of two-year old C. hybrid were showed single curve. The one-year old and two-year old C. hybrids had low net photosynthetic rate under three light intensities. The changes of chlorophyll fluorescence parameter indicated that both of them had highest photosystem activity under 36 % of full light intensity. Photo-inhibition of C. hybrid appeared under light intensity of 850 μmol·m^-2·s^-1, but could be relieved when photosynthetically active radiation（PAR） declined. C. hybrid leaves maintained high levels of chlorophyll fluorescence parameter and showed better response to light under light intensity of 364-400μmol·m^-2·s^-1.