3个中山杉杂种无性系及其亲本的光合特性比较

对‘中山杉405’(Taxodium‘Zhongshanshan 405’)、‘中山杉406’(T.‘Zhongshanshan 406’)和‘中山杉407’(T.‘Zhongshanshan 407’)及其母本墨西哥落羽杉(T.mucronatum Tenore)和父本落羽杉〔T.distichum(L.)Rich.〕在7月份、9月份和10月份的光合参数进行了测定,并比较了3个无性系净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)和水分利用效率(WUE)的杂种优势。结果显示:不同月份3个无性系及其亲本的Pn值有明显差异,导致光响应曲线明显不同,但3个无性系的光响应曲线基本一致;3个无性系的Pn值在不同月份都高于落羽杉,且‘中山杉405’的Pn值高于另2个无性系。3个无性系及其亲本的光补偿点总体上表现为7月份最高、10月份最低,其中7月份墨西哥落羽杉的光补偿点显著高于3个无性系及落羽杉(P<0.05);3个无性系和墨西哥落羽杉的光饱和点则为9月份最高、7月份最低,而落羽杉的光饱和点为9月份最高、10月份最低。7月份3个无性系与其亲本的Pn日变化曲线均呈不规则型,低谷出现在中午12:00左右;9月份和10月份3个无性系和墨西哥落羽杉的Pn日变化曲线均呈单峰型,峰值出现在上午10:00;落羽杉的Pn值从上午8:00开始呈持续降低的趋势,且全天都明显低于其他树种。不同月份3个无性系的Pn、Gs、Tr和WUE的杂种优势有明显差异,总体上看,‘中山杉405’的Pn、Gs和Tr在3个月份中均保持较高的杂种优势率,而‘中山杉406’9月份的杂种优势率最高,‘中山杉407’则在7月份杂种优势率最高;3个无性系的WUE仅在10月份有明显的杂种优势,且‘中山杉405’和‘中山杉406’的杂种优势率远高于‘中山杉407’;‘中山杉405’各项指标的杂种优势率总体上高于另2个无性系。研究结果表明:3个中山杉无性系的光合能力接近其母本墨西哥落羽杉、高于父本落羽杉,其中‘中山杉405’杂种优势明显。

Comparison of photosynthetic characteristics of three clones of Taxodium 'Zhongshanshan' and their parents

Photosynthetic parameters of Taxodium ‘Zhongshanshan 405’,T.‘Zhongshanshan 406’,and T.‘Zhongshanshan 407’and their female parent T.mucronatum Tenore and male parent T.distichum(L.) Rich.in July,September and October were determined,and heterosis of three clones in netphotosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr) and water use efficiency(WUE) were compared.The results show that Pn value of three clones and their parents in different months have a significant difference,which lead to a significant difference in their Pn light response curve,but Pn light response curve of three clones are generally consistent.Pn value of three clones in different months are all higher than that of T.distichum and that of T.‘Zhongshanshan 405’is higherthan that of other two clones.Light compensation point(LCP) of three clones and their parents appear generally a trend of the highest in July and the lowest in October,in which,LCP of T.mucronatum inJuly is significantly higher than that of three clones and T.distichum(P<0.05).And light saturation point(LSP) of three clones and T.mucronatum appear generally a trend of the highest in September and the lowest in July,but that of T.distichum with the highest in September and the lowest in October.In July,Pn diurnal change curve of three clones and their parents all are irregular type and the valley valueappears about at noon 12: 00.In September and October,Pn diurnal change curve of three clones and T.mucronatum all are a single-peak curve and the peak value appears at 10 00 am,while Pn value of T.distichum declines continuously from 8: 00 am and obviously lower than that of other trees during the whole day.Heterosis of three clones in Pn,Gs,Tr and WUE in different months exists an obvious difference.Generally,Pn,Gs and Tr of T.‘Zhongshanshan 405’ keep a high heterosis rate in three months,those of T.‘Zhongshanshan 406’have the highest heterosis rate in September,while those of T.‘Zhongshanshan 407’have the highest heterosis rate in July.And WUE of three clones have an obvious heterosis only in October and that of T.‘Zhongshanshan 405’and T.‘Zhongshanshan 406’is much higher than that of T.‘Zhongshanshan 407’.Generally,heterosis of every indexes of T.‘Zhongshanshan405’is higher than that of other two clones.It is suggested that photosynthetic capacity of three clones isclose to their female parent T.mucronatum and better than that of their male parent T.distichum,in which,heterosis of T.‘Zhongshanshan 405’is obvious.