摘要： 为了揭示干旱半干旱区夏玉米品种对干旱胁迫的光合生理响应机制，以3个常用夏玉米品种（浚单20、津北288和迪卡667）为研究对象，分别对其实施不同程度的干旱胁迫处理（对照CK，轻度胁迫LD和重度胁迫HD），利用便携式光合作用系统Li-6400测定了叶片净光合速率-光合有效辐射强度响应（Pn-PAR）和净光合速率-细胞间隙二氧化碳浓度响应（A-Ci），并利用便携调制叶绿素荧光仪MINI-PAM测定了叶绿素荧光参数对光合有效辐射强度的响应。结果发现：3个玉米品种，Pn与气孔导度（Gs）随光合有效辐射强度增加的变化规律相似，干旱胁迫程度的增加，Pn-Gs响应关系左移；无论何种处理，Pn下降的同时Ci值不变或升高；重度胁迫（HD）显著降低了3个品种的初始羧化效率（CE）和光合能力（Amax）；与对照相比，干旱胁迫（包括LD和HD）降低了浚单20和迪卡667 2个品种的非光化学淬灭系数（qN）和调节性能量耗散的量子产量（Y（NPQ））2个指标的响应，增大了非调节性能量耗散的量子产量（Y（NO））的响应值；仅在重度胁迫（HD）下，津北288的光化学淬灭系数（qP）降低；与对照相比，在轻度胁迫（LD）下，津北288的最大净光合速率（Pmax）和初始量子效率（AQY）有少许提高。相对于其他2个品种，津北288在轻度干旱胁迫条件下可降低qQ，增大Y（NO）来维持高的Pmax和AQY，这些结果不仅表明津北288具有较强的干旱胁迫耐受性，且能为作物耐旱性品系的筛选提供技术参考。

关键词: 玉米, 干旱胁迫, 光合-光响应曲线, 光合-胞间CO₂曲线, 快速光曲线

Abstract: In order to explore the photosynthetic physiological response mechanisms of three summer maize varieties (Xundan 20, Jinbei 288 and Dika 667) which were commonly cultivated in arid and semi-arid areas to drought stress, these three varieties were treated under different drought stresses (including non-drought treatment (CK), light drought (LD) and heavy drought (HD)). Responses of net photosynthetic rate to light intensity (Pn-PAR) and net photosynthetic rate to intercellular CO₂ concentration (A-Ci) were estimated by the portable photosynthesis system Li-6400, and responses of chlorophyll fluorescence parameters to light intensity were measured by portable modulation chlorophyll fluorescence meter MINI-PAM, respectively. The results were as follows. As for all these three varieties, the response modes of Pn and stomatal conductance (Gs) to PAR were similar among these three maize varieties, and the responses of Pn to Gs shifted to left along the drought stress gradient. The initial chemical efficiency (CE) and photosynthetic capacity (Amax) were significantly lower under heavy drought treatment than under the other two treatments for each of the three varieties. Compared with the results under CK treatment, the non-photochemical quenching coefficient (qN) and the quantum yield of the regulatory energy dissipation (Y (NPQ)) were lower and the quantum yield of non-regulated energy dissipation (Y(NO)) was higher under LD or HD treatment for the two varieties of Jundan 20 and Dika 667; and the photochemical quenching coefficient (qP) was lower under HD treatment for the variety of Jinbei 288. Compared with the results under CK treatment, the maximum net photosynthetic rate (Pmax) and initial quantum efficiency (AQY) were a little higher under LD treatment for the variety of Jinbei 288. Compared with the other two varieties, the Pmax and AQY showed higher tolerance to drought stress by keeping relatively lower qQ and lower Y(NO) for the variety of Jinbei 288, and these results not only showed the greater tolerance of Jinbei288 to drought stress, but also provided reference for the screening of crop varieties for drought tolerance.

Key words: Maize, Drought stress, Photosynthetic-light response curve, Photosynthetic-intercellular CO₂ curve, Rapid light curve

中图分类号: 

• S513