干旱胁迫条件下菊苣的光合响应

研究了3种具有不同抗旱性的菊苣(Cichorium intybus)航天诱变新品系PA 43、PA 82和亲本普那菊苣]的光合特性及对干旱胁迫的响应。结果表明，3个菊苣品系的净光合速率（Pn）、蒸腾速率（Tr）和气孔导度（Cond）日变化趋势都是双峰曲线。午间有明显“午休”现象，且导致午休的主要原因是非气孔因素。PA 82的Pn、Tr、Cond值均最高，PA 43的相应值均最小;3个菊苣品系的胞间CO2浓度（Ci）在10:00－12:00时比较低，其变化曲线与Pn相反。水分利用效率（WUE）以PA 82为最高，普那菊苣居中，PA 43为最低。随着干旱胁迫程度的加剧，3个菊苣品系的Pn、Tr、Cond、暗适应下PSⅡ最大光化学效率（Fv/Fm）、暗适应下PSⅡ的潜在活性（Fv/Fo）、光化学猝灭系数（qP）均有一定程度的降低。其中，PA 82下降速度慢、幅度小，PA 43下降速度快、幅度大。Ci、qN值随着胁迫程度的加剧呈上升趋势。其中，PA 82上升速度慢、幅度小，PA 43上升速度快、幅度大。相对于抗旱性弱的菊苣PA 43，抗旱性强的菊苣PA 82、 普那菊苣在受到严重干旱胁迫时，具有较强的抵抗干旱的能力。

Photosynthetic properties of three chicory lines and their responses to drought stress

The photosynthetic properties of three chicory (Cichorium intybus) lines were investigated under water stress through pot experiment. The lines which included space mutagenesis bred lines(PA 82 and PA 43),and their initial strain (Puna chicory) were studied using Li 6400 portable photosynthesis system. The results showed that, diurnal net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Cond) presented as double peak curves. There was an obvious mid day Pn depression, which was caused by nonstomatal factors. The highest Pn, Tr and Cond values were observed in PA 82, and the lowest corresponding values were observed in PA 43 (P<0.05). Intercellular CO2 concentration (Ci) of three lines showed an opposite course to that of Pn, which reached its valley at 10:00 12:00. PA 82 had the highest water use efficiency (WUE), followed by Puna chicory, then PA 43. Both of them indicated a good adaptation to changes of light intensity. Pn, Tr, Cond, maximal photochemical efficiency of PS II in dark adaptation (Fv/Fm), potential photochemical efficiency (Fv/F0), and coefficient of photochemical quenching (qP) decreased with the aggravation of water deficit. Among the three lines, the parameters of PA 43 dropped to a greater extent at the highest speed, followed by Puna chicory, then PA 82. With the aggravation of water deficit, Ci and co efficient of nonphotochemical quenching (qN) increased to a greater extent at the highest speed in PA 43. The results suggest that PA 82 and Puna chicory have higher resistance against severe water deficit in comparison with PA 43.