遮荫对油用牡丹植株生长和光合特性的影响

Effects of Shading on Growth and Photosynthetic Characteristics of Oil Peony

设置100%全光照（L0）、50%全光照（L1）、25%全光照（L2）和15%全光照（L3）4种光环境,分析不同遮荫环境对油用牡丹的生长、光合作用及叶绿素荧光参数的影响。结果表明：（1）油用牡丹的花朵数量、比叶重、气孔密度在L2和L3处理下显著低于L0处理,但L1较L0无显著变化;随着遮荫水平增加,油用牡丹种子数量、气孔器面积百分比逐渐下降,且在4个不同处理间差异显著。（2）油用牡丹叶片最大净光合速率（Pmax）、光补偿点（LCP）和光饱和点（LSP）在遮荫条件下均有不同程度降低,L2和L3处理的Pmax和LSP显著低于L0,但L1较L0无显著变化。（3）L3处理的光系统Ⅱ（PSⅡ）的最大量子效率（Fv/Fm）为0.76,显著低于其余3个光照处理;随光化光诱导时间的增加,开放的PSⅡ反应中心的激发能捕获效率（Fv′/Fm′）呈逐渐下降并趋于稳定的趋势,而PSⅡ的实际量子产量效率（ΦPSⅡ）、光化学猝灭系数（qP）、非光化学猝灭系数（NPQ）呈逐渐增加并趋于稳定的趋势,稳定后的Fv′/Fm′、ΦPSⅡ值表现为L0〉L1〉L2〉L3,NPQ大小顺序为L3〉L2〉L1〉L0,但不同处理间的qP无显著差异。研究发现：过度遮荫（15%~25%自然光强）严重抑制了油用牡丹的净光合速率,而且与产量直接相关的花朵数量和种子数量也显著下降,最终造成严重减产;在云南昆明地区50%~100%之间的自然光可能是油用牡丹较为合适的生长光强。

The growth,photosynthesis and chlorophyll fluorescence parameters of oil peony were measured under 100% of full light（L0）,50% of full light（L1）,25% of full light（L2）and 15% of full light（L3）,respectively.The results showed that：（1）the number of flowers,leaf dry mass per unit area（LMA）andstomatal density of L0 treatment were significantly higher than that of L2 and L3,but there was no significant difference with L1treatment;With the increase of shading levels,the number of seed,stomatal area percentage decreased gradually and there was significant difference among treatments;（2）the photosynthetic rate（Pmax）,light compensation point（LCP）and light saturation point（LSP）decreased with the increase of shading;Pmaxand LSP of L0 treatment were significantly higher than that of L2 and L3,but there was no significant difference with L1treatment;（3）the maximum quantum efficiency of photosynthetic system Ⅱ（Fv/Fm）of L3 treatment was 0.76,which was significantly lower than that of other treatments;With the increase of induction time by actinic light,the induction time by actinic light（Fv′/Fm′）decreased gradually and tended to be stable;the PSⅡ quantum yield efficiency（ΦPSⅡ）,photochemical quenching（qP）and non photochemical quenching（NPQ）increased gradually and tended to be stable.The order of Fv′/Fm′andΦPSⅡafter stable was L0L1L2L3,while NPQ was L3L2L1L0,and there was no significant difference in qP among treatments.It is indicated that over shading（15%-25% of full light）severely inhibited the net photosynthetic rate of oil peony,and the number of flowers and seeds which directly related to the yield was also significantly decreased,resulting in a serious reduction in production.Therefore,50%-100% of full light may be more suitable for the growth of oil peony in Kunming area,Yunnan.