滇楸幼苗无性系光合特性的比较1）

摘要

We used two-year-old Catalpa duclouxii seedlings by grafting to compare their differences of the photosynthetic charac-teristics in Jianghan Plain under drought stress.Drought inhibited the seedling growth severely, and there were no signifi-cant differences in growth traits of August and December between different clones of C.duclouix i ( 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 8-14μmol· m-2· s-1, plummeted after 7:00 AM, and maintained in 2-6μmol· m-2· s-1 low ground.The order of the day total Pn was 008-1>Y011-1>Y023-2>Y020-6>8402>Y011-4>YN014-5, the or-der 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 be-tween 324-796μmol·m -2 · s-1 and 4.58-8.17μmol· m-2 · s-1 , respectively, and they were far below than the trait val-ues under the normal water supply.By correlation analysis, WUE was both significant correlated with the growth traits and photosynthetic characteristics (P<0.05).When the seedlings subjected to drought stress, WUE became important particu-larly.According the growth performance, WUE and photosynthetic characteristics, Y011-4 had stronger growth potential and photosynthetic capacity among five clones in Jianghan Plain.%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、Y 011－4、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。