滇楸幼苗无性系光合特性的比较

Photosynthetic Characteristics of Five Catalpa duclouxii Seedling Clones

以2年生滇楸嫁接苗为试验材料,对不同无性系干旱胁迫下的光合特征进行比较。结果表明：持续干旱及高温严重抑制了滇楸苗期生长;不同无性系间,8月和12月的生长性状差异均不显著（P〉0.05）;各无性系光合特征不再出现明显的单峰或双峰曲线。净光合速率（Pn）最大值（8~14μmol·m-2·s-1）均出现在7：00,之后直线下滑,维持在2~6μmol·m-2·s-1的低位,Pn日总量由大到小的顺序为：008-1、Y011-1、Y023-2、Y020-6、8402、Y011-4、YN014-5。瞬时水分利用效率（WUE）日均值,由大到小的顺序为：008-1、Y011-4、YN014-5、Y020-6、Y011-1、Y023-2、8402。各无性系光饱和点（LSP）与最大净光合速率（Pnmax）分别为324~796、4.58~8.17μmol·m-2·s-1,远低于正常水分供应下的特征值。WUE与生长性状及重要光合特征均显著相关（P〈0.05）,受到干旱胁迫时,WUE的高低尤为重要。根据生长表现,结合WUE和光合特性,当遭受干旱高温胁迫时,5个滇楸无性系中,Y011-4具有相对较高的生长势和光合能力。

We used two-year-old Catalpa duclouxii seedlings by grafting to compare their differences of the photosynthetic characteristics in Jianghan Plain under drought stress. Drought inhibited the seedling growth severely,and there were no significant differences in growth traits of August and December between different clones of C. duclouxii（ P〉0.05）. Photosynthetic characteristics of the clones were no longer apparent unimodal or bimodal curves,the maximum net photosynthetic rate（ Pn） occurred at 7： 00 AM in 8-14 μmol·m-2·s-1,plummeted after 7： 00 AM,and maintained in 2-6 μmol·m-2·s-1low ground. The order of the day total Pnwas 008-1〉Y011-1〉Y023-2〉Y020-6〉8402〉Y011-4〉YN014-5,the order of the daily average of instantaneous water use efficiency（ WUE） was 008-1〉Y011-4〉YN014-5〉Y020-6〉Y011-1〉Y023-2〉8402. The light saturation point（ LSP） and the maximum net photosynthetic rate（ Pnmax） of these clones were between 324-796 μmol·m-2·s-1and 4.58-8.17 μmol·m-2·s-1,respectively,and they were far below than the trait values under the normal water supply. By correlation analysis,WUEwas both significant correlated with the growth traits and photosynthetic characteristics（ P〈0.05）. When the seedlings subjected to drought stress,WUEbecame important particularly. According the growth performance,WUEand photosynthetic characteristics,Y011-4 had stronger growth potential and photosynthetic capacity among five clones in Jianghan Plain.