Lu Zhifeng, Lu Jianwei, Pan Yonghui, Li Xiaokun, Cong Rihuan, Ren Tao
Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River) Ministry of Agriculture, Wuhan 430070, China.
Funct Plant Biol. 2016 Sep;43(9):880-891. doi: 10.1071/FP16098.
Cultivars with higher potassium utilisation efficiency (KUtE) are likely to have superior photosynthesis (A) under K deficiency. However, the inner link between KUtE and photosynthesis remains unclear. A quantitative analysis of stomatal (SL), mesophyll conductance (MCL) and biochemical (BL) limitations on A in response to K supplementation was performed on upper and lower leaves of Brassica napus L. Huayouza No. 9 (H9, high KUtE) and Zhongshuang No. 11 (Z11, low KUtE). Both cultivars showed remarkable improvement in leaf area and lower leaf photosynthesis with elevated K supply. The total photosynthetic limitation of Z11 in lower leaf was 51.9% higher than that of H9 under K deficiency. Most of limitation under K deficiency was dominated by MCL for Z11, yet it was equally controlled by MCL and SL for H9. Nevertheless, with increasing K supply, SL became the primary limitation for both cultivars. Z11 needed a 12.0% higher leaf K concentration to avoid A decline, and higher K-based thresholds for each limitation. Overall, cultivars higher in KUtE have improved inherent leaf photosynthesis and area, and present lower K-based thresholds for SL, MCL and BL.
钾利用效率（KUtE）较高的油菜品种在缺钾条件下可能具有更强的光合作用（A）。然而，KUtE与光合作用之间的内在联系尚不清楚。本研究以华油杂9号（H9，KUtE高）和中双11号（Z11，KUtE低）甘蓝型油菜的上部和下部叶片为材料，对补充钾素后气孔导度（SL）、叶肉导度（MCL）和生化限制（BL）对光合作用的影响进行了定量分析。随着钾供应增加，两个品种的叶面积和下部叶片光合作用均显著提高。缺钾条件下，Z11下部叶片的总光合限制比H9高51.9%。缺钾条件下，Z11的限制主要由MCL主导，而H9则由MCL和SL共同控制。然而，随着钾供应的增加，SL成为两个品种的主要限制因素。Z11需要高12.0%的叶片钾浓度才能避免光合速率下降，且各限制因素的钾阈值更高。总体而言，KUtE较高的品种具有更高的叶片固有光合作用和叶面积，且SL、MCL和BL的钾阈值更低。
