【摘要】 【目的】探讨叶片蜡质含量对干旱胁迫下小麦光合特性的影响。【方法】本研究以一对小麦近等基因系多蜡质品系JM205和少蜡质品系JM204为试验材料,将二者种植在同一盆中,在人工气候室采用逐渐干旱的方式模拟田间干旱过程中的土壤水分变化。随着干旱处理时间的延长,土壤相对含水量逐渐降低,同步测定了不同土壤相对含水量下小麦旗叶的水势、光合气体交换参数及荧光参数。【结果】轻度干旱胁迫（土壤相对含水量在60%—49%）下,多蜡质品系JM205与少蜡质品系JM204旗叶的光合速率（Pn）无显著差异,随着干旱程度的加重,多蜡和少蜡质品系的光合速率都逐渐降低,但少蜡质品系JM204下降幅度更大。在中度干旱胁迫（土壤相对含水量在49%—32%）下,多蜡质品系比少蜡质品系具有较高的水势和较大的气孔开度,因此CO₂供应充足,光合速率更高;少蜡质品系的PSII实际光化学效率（ΦPSⅡ）和最大光化学效率（Fv/Fm）较多蜡质品系下降更快,说明少蜡质品系PSII电子传递受阻情况和光抑制比多蜡质品系更严重;快速叶绿素荧光动力学曲线参数分析（JIP-test）发现PSII电子传递受阻主要是因为受体侧QA到QB电子传递限制。在重度干旱胁迫（土壤相对含水量下降到32%以下）时,多蜡质与少蜡质品系的水势和光合能力都大幅下降且二者间没有明显差异。【结论】本研究表明,多蜡质品系JM205在中度干旱胁迫（土壤相对含水量49%—32%范围）下具有较高的光合优势;本研究为小麦抗旱性选育与利用提供了理论依据,并对进一步的研究提供了建议。更多还原

【Abstract】 【Objective】 The objective of this paper was to investigate the effects of different drought levels on the photosynthetic characteristics of wheat with different wax contents. 【Method】 A pair of wheat near-isogenic lines(NILs), including high-wax line JM205 and low-wax line JM204, were used as experimental materials to simulate the process of soil moisture change in the field by means of gradual drought stress in the artificial climate chamber. The two wheat near-isogenic lines with different waxy contents were planted in the same pot to ensure the same drought degree. With the prolongation of drought treatment, the relative soil water content decreased gradually. Water potential, photosynthetic gas exchange parameters and fluorescence parameters of wheat flag leaf under different soil water contents were measured. 【Result】 Under low water stress(60%-49% of relative soil water content), there was no significant difference in photosynthetic rate(Pn) between flag leaf of JM205 and JM204, however, the photosynthetic rate of both wax and waxy lines decreased gradually, but the less waxy line JM204 showed a greater decline. Under moderate drought stress(Relative soil water content between 49% and 32%), the high-wax plant had higher water potential and larger stomatal opening than that of the low-wax one, so the CO2 supply was sufficient and the photosynthetic rate was higher. Under moderate drought stress, the PSII actual photochemical efficiency(ΦPSⅡ) and maximum photochemical efficiency(Fv/Fm) decreased more rapidly in the low-wax line, which indicated that PSII electron transfer inhibition and light inhibition were more serious. The JIP-test analysis found that blocked PSII electron transport was mainly due to QA to QB receptor-side electron transfer restrictions. In contrast, the high-wax line maintained relatively higher photosynthetic capacity under drought conditions, with a smoother electron transfer and less excess light energy, resulting in less light suppression. When relative soil water content dropped below 32%, the water potential and photosynthetic capacity of both NILs decreased significantly and there was no significant difference between them. 【Conclusion】 This study preliminarily improved understanding of the physiological mechanism of leaf wax improving drought tolerance of plants, and the high-wax line JM205 has significant drought resistance in the soil moisture range of 49%-32%, providing theoretical basis for selection and cultivation of drought-resistant wheat varieties.更多还原