对4 月份至11 月份金叶银杏‘万年金’(Ginkgo biloba ‘Wannianjin’)32 个半同胞子代无性系与亲本的叶色差异进行比较;比较了不同色系叶片的色素含量和比值及叶色参数(L*、a*和b*)的变化,分析了叶色参数与叶片色素含量的相关性;并观察了不同色系的叶绿体超微结构。结果表明:32 个半同胞子代无性系可被分为金黄、浅黄、草绿和蓝绿4 个色系。随时间推移,草绿和蓝绿色系叶片的总叶绿素(Chl)、叶绿素a(Chla)、叶绿素b(Chlb)和类胡萝卜素(Car)含量均呈“双峰型”变化趋势,Car/ Chl 和Car/ Chla 比值的变幅均较小;而金黄和浅黄色系叶片的上述色素含量呈“升高—降低—升高”变化趋势,Car/ Chl 和Car/ Chla 比值总体呈“迅速下降—相对稳定—缓慢升高”的变化趋势。各色系叶片的上述色素含量在夏季均不同程度下降,Car/ Chlb 比值变化差异较大,且金黄和浅黄色系的各色素含量均低于草绿和蓝绿色系。随时间推移,金黄和浅黄色系叶片的L*、a*和b*值以及草绿和蓝绿色系叶片的L*和b*值均先降低后升高,后2 个色系的a*值则先升高后下降;并且,前2 个色系的L*和b*值总体上显著高于后2 个色系,而a*值则总体上低于后2 个色系。金黄色系的Chla 和Chl 含量与L*和a*值显著负相关,而其Car/ Chl 和Car/ Chla 比值则与L*、a*和b*值显著或极显著正相关;浅黄色系的Chlb 含量与a*值显著负相关,其Car/ Chla 比值与L*和b*值以及Car/ Chlb 比值与a*值均显著正相关;草绿色系的Chla 含量与L*值显著负相关,其Car/ Chla 比值与L*和b*值以及Car/ Chlb 比值与a*值均显著正相关;这3 个色系叶片的其余指标间以及蓝绿色系叶片的各指标间均无显著相关性。观察结果显示:金黄和浅黄色系的叶绿体基粒片层发育不健全,基粒片层可见但排列较疏松,且无明显垛叠,分布范围小而稀疏;蓝绿和草绿色系叶绿体的基粒类囊体垛叠层数均较多,基粒片层发达且排列紧致、整齐,分布范围大而稠密。综合分析结果表明:‘万年金’4 个色系半同胞子代无性系叶片的呈色差异和叶色变化由多种因素控制,其中,Car/ Chl 和Car/ Chla 比值高且叶绿体基粒片层发育不健全是叶片呈黄色的主要原因。

Differences in leaf color of 32 half-sib progeny clones and parents of ‘Wannianjin’of golden-leaf ginkgo (Ginkgo biloba Linn.) from April to November were compared. Changes in leaf pigment contents and ratios and leaf color parameters of (L*, a* and b*) different color series were compared,correlation between leaf color parameters and leaf pigment contents was analyzed, and ultrastructure of chloroplast of different color series was observed. The results show that 32 half-sib progeny clones are divided into four color series including golden yellow, light yellow, grass green and blue-green. As time goes on, contents of total chlorophyll (Chl), chlorophyll a (Chla), chlorophyll b (Chlb) and carotenoid (Car) in leaf of grass green and blue-green color series all appear the trend of “double-peak”, change ranges in ratios of Car/ Chl and Car/ Chla both are smaller; while contents of the above pigments in leaf of golden yellow and light yellow color series appear the trend of  “increasing-decreasing-increasing”, and ratios of Car/ Chl and Car/ Chla generally appear the trend of “decreasing rapidly -relatively stable - increasing slowly”. Contents of the above pigments in leaf of different color series during summer all decrease at different degrees, difference in their Car/ Chlb ratio change is large, and pigment contents of golden yellow and light yellow color series are all lower than those of grass green and blue-green color series. As time goes on, L*, a* and b* values in leaf of golden yellow and light yellow color series and L* and b* values in leaf of grass green and blue-green color series all decrease at first and then increase, while a* value of the latter two color series increases at first and then decreases; and L* and b* values of the first two color series are generally significantly higher than those of the latter two color series, while a* value is generally lower than that of the latter two color series. There are significantly negative correlations of Chla and Chl contents of golden yellow color series with L* and a* values, while significantly or extremely significantly positive correlations of its Car/ Chl and Car/ Chla ratios with L*, a* and b* values. There is a significantly negative correlation of Chlb content of light yellow color series with a* value, and significantly positive correlations of its Car/ Chla ratio with L* and b* values and Car/ Chlb ratio with a* value. There is a significantly negative correlation of Chla content of grass green color series with L* value, and significantly positive correlations of its Car/ Chla ratio with L* and b* values and Car/ Chlb ratio with a* value. There is no significant correlation among other indexes in leaf of three color series and among indexes in leaf of blue-green color series. The observation result shows that development of grana lamella in chloroplast of golden yellow and light yellow color series is imperfect, which is visible with a loose arrangement, but without obviously stacking, its distribution is small and sparse. Stacking layers of grana thylakoids in chloroplast of blue-green and grass green color series are more, grana lamella is developed with a compact and regular arrangement, its distribution is large and dense. The comprehensive analysis result indicates that coloring difference and leaf color change of four color series of half-sib progeny clones of ‘Wannianjin’ are controlled by many factors, in which, high ratios of Car/ Chl and Car/ Chla and imperfect development of grana lamella in hloroplast are the main reasons for appearing yellow leaf.