Phytopathology. 2001 Feb;91(2):212-20. doi: 10.1094/PHYTO.2001.91.2.212.
ABSTRACT The effects of rust (caused by Uromyces appendiculatus) and anthracnose (caused by Colletotrichum lindemuthianum) and their interaction on the photosynthetic rates of healthy and diseased bean (Phaseolus vulgaris) leaves were determined by gas-exchange analysis, in plants with each disease, grown under controlled conditions. The equation P(x)/P(0) = (1 - x)() was used to relate relative photosynthetic rate (P(x)/P(0)) to proportional disease severity (x), where beta represents the ratio between virtual and visual lesion. The beta values obtained for rust were near one, indicating that the effect of the pathogen on the remaining green leaf area was minimal. The high values of beta obtained for anthracnose (8.46 and 12.18) indicated that the photosynthesis in the green area beyond the necrotic symptoms of anthracnose was severely impaired. The impact of anthracnose on bean leaf photosynthesis should be considered in assessments of the proportion of healthy tissue in diseased leaves. The accurate assessment of the healthy portion of the leaf could improve the use of concepts such as healthy leaf area duration and healthy leaf area absorption, which are valuable predictors of crop yield. The equation used to analyze the interaction between rust and anthracnose on the same leaf was P(z) = P(0) (1 - x)(x) x (1 - y)(y), where P(z) is the relative photosynthetic rate of any given leaf, P(0) is the maximum relative photosynthetic rate, x is anthracnose severity, y is rust severity, betax is the beta value for anthracnose in the presence of rust, and betay is the beta value for rust in the presence of anthracnose. From the resulting response surface, no interaction of the two diseases was observed. Dark respiration rate increased on diseased leaves compared with control leaves. The remaining green leaf area of leaves with both diseases was not a good source to estimate net photosynthetic rate because the effect of anthracnose extended far beyond the visual lesions, whereas the effect of rust on photosynthesis was essentially limited to the pustule plus halo.
摘要 在受控条件下，对分别患有叶锈病（由禾柄锈菌引起）和炭疽病（由胶孢炭疽菌引起）以及同时患有两种病害的豌豆植株进行气体交换分析，以确定病害及其互作对健康和染病豌豆叶片光合速率的影响。文中使用方程 P(x)/P(0) = (1 - x)() 将相对光合速率 (P(x)/P(0)) 与比例病害严重度 (x) 联系起来，其中β代表虚拟和视觉病变之间的比值。禾柄锈菌引起的叶锈病的β值接近 1，表明病原菌对剩余绿叶面积的影响最小。炭疽病引起的β值较高（8.46 和 12.18），表明炭疽病的绿色区域内的光合作用在超出炭疽病坏死症状的区域严重受损。在评估染病叶片中健康组织的比例时，应考虑炭疽病对豌豆叶片光合作用的影响。准确评估叶片的健康部分可以提高健康叶面积持续时间和健康叶面积吸收等概念的应用，这些概念是作物产量的有价值预测指标。用于分析同一叶片上叶锈病和炭疽病相互作用的方程为 P(z) = P(0) (1 - x)(x) x (1 - y)(y)，其中 P(z) 是任何给定叶片的相对光合速率，P(0) 是最大相对光合速率，x 是炭疽病严重度，y 是叶锈病严重度，betax 是叶锈病存在时炭疽病的β值，betay 是叶锈病存在时叶锈病的β值。从得到的响应曲面来看，两种病害之间没有相互作用。与对照叶片相比，染病叶片的暗呼吸速率增加。同时患有两种病害的叶片的剩余绿叶面积并不是估算净光合速率的良好来源，因为炭疽病的影响远远超出了可见的病变范围，而叶锈病对光合作用的影响基本上局限于疱斑和晕圈。
