春伐对鄂桑1号光合生理参数的影响

Effects of Spring-Cutting on Photosynthetic Physiological Parameters of Morus alba L. cv. E-sang No.1

在自然条件下,测定了鄂桑1号(Morus alba L.cv.E-sang No.1)和湖桑32号[M.alba L.var.multicaulis(Perrott.)Loud.cv.Husang No.32]桑树品种春伐后,植株叶片的各项光合生理参数及变化规律,并对其进行了比较分析。结果表明,2个桑树品种的叶片净光合速率(Pn)日变化曲线均呈双峰型,有明显的"光合午休"现象,其气孔限制为光合能力下降的主要原因;表观光能利用效率(LUE)为鄂桑1号<湖桑32号,瞬时水分利用效率(WUEi)为鄂桑1号>湖桑32号,潜在水分利用效率(WUEp)为湖桑32号>鄂桑1号;光饱和点(LSP)为湖桑32号[1 412.46μmol/(m2·s)]>鄂桑1号[1 201.63μmol/(m2·s)],光补偿点(LCP)为湖桑32号[26.99μmol/(m2·s)]<鄂桑1号[31.02μmol/(m2·s)],表观量子效率(AQY)、羧化效率(CE)、光合能力(Pm)、1,5-二磷酸核酮糖(Ru BP)最大再生速率(Ru BPmax)均为湖桑32号>鄂桑1号,且Pm、Ru BPmax的差异达显著性水平(P<0.05);桑树叶片Pn季节变化在5月11日和5月16日,湖桑32号的Pn值显著大于鄂桑1号(P<0.05),而7月30日和8月30日,鄂桑1号的Pn值显著大于湖桑32号(P<0.05)。光合有效辐射(PAR)是影响桑树Pn最重要的生态因子,而空气相对湿度(RH)对气孔导度(Gs)和蒸腾速率(Tr)有较明显的影响。

The various photosynthetic physiological parameters and its changing regularities of Morus alba L.cv.E-sang No.1 and M.alba L.var.multicaulis （Perrott.） Loud.cv.Husang No.32 after spring cutting were measured and analyzed.The results showed that the diurnal variation of net photosynthetic rate （Pn） of both mulberry leaves was in double-curve form.There were obvious midday photosynthetic depression.The stomatal limitation was the main cause for the decline of photosynthetic capacity.The light use efficiency （LUE） of M.alba cv.E-sang No.1 was lower than that of M.alba var.multicaulis cv.Husang No.32.The intrinsic water use efficiency （WUEi） of M.alba cv.E-sang No.1 was higher than that of M.alba var.multicaulis cv.Husang No.32.The potential water use efficiency （WUEp） of M.alba var.multicaulis cv.Husang No.32 was higher than that of M.alba cv.E-sang No.1.The light saturation point （LSP） of M.alba var.multicaulis cv.Husang No.32 [1 412.46 μ mol （m^2·s）] was higher than that of M.alba cv.E-sang No.1 [1 201.63 μmol/（m^2·s）].The light compensation point （LCP） of M.alba cv.Husang No.32[26.99 μ mol/（m^2·s）] was lower than that of M.alba cv.E-sang No.1[31.02 μmol/（m^2·s）].The apparent quantum yield （AQY）,carboxylation efficiency （CE）,photosynthetic capacity （Pm） and max regeneration velocity of ribulose-1,5-bisphosphate （RuBPmax） of M.alba var.multicaulis cv.Husang No.32 were higher than those of M.alba cv.E-sang No.1.The Pm and RuBPmax had significant difference （P〈0.05）.The Pn seasonal variation of M.alba var.multicaulis cv.Husang No.32 was higher than that of M.alba cv.E-sang No.1 in May 11th and May 16th.The Pn seasonal variation of M.alba var.multicaulis cv.Husang No.32 was lower than that of M.alba cv.E-sang No.1 in July 30th and August 30th.The Pn all had significant difference （P〈0.05）.Photosynthetic active radiation （PAR） was the major ecological factor for the Pn.The relative humidity affected the stomatal conductance（Gs） and transpiration rate （Tr）.