Stetina K C, Stetina S R, Russin J S
Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge 70803.
Plant Dis. 2006 Jan;90(1):39-43. doi: 10.1094/PD-90-0039.
Rhizoctonia foliar blight, caused by Rhizoctonia solani Kühn anastomosis group 1, causes rapid and severe destruction of soybean foliage and pods during hot, wet weather. The objectives of this study were to determine the yield components affected by this disease and whether rating pod damage or foliar damage provides a more reliable method of assessing disease severity relative to impact on yield. Disease severity in the moderately resistant cv. NK S57-11 and the susceptible cv. Buckshot 723 was assessed in field plots in 1996 and 1997 using foliar and pod ratings (0-to-10 scale corresponding to 0 to 100% of tissue affected). Based on results from regression analysis, pod number, seed number, and seed weight per plot decreased as disease severity increased, whereas the proportion of partially filled pods and the weight of 100 seed were not affected. Yield loss appeared to be due primarily to loss of entire pods. Foliar and pod assessments of disease severity correlated positively in 1996 (r = 0.8343) and 1997 (r = 0.5958) for both cultivars, which suggests that either method can be used to identify relative differences among cultivars. However, pod assessments accounted for more variability than foliar assessments under low-disease conditions. Plants exhibiting moderate to severe symptoms of Rhizoctonia foliar blight also retained green stems and pods at harvest, which was evidence of delayed maturity.
由立枯丝核菌库恩融合群1引起的大豆丝核菌叶枯病，在炎热潮湿的天气中会迅速且严重地破坏大豆叶片和豆荚。本研究的目的是确定受该病害影响的产量构成因素，以及评估豆荚损伤或叶片损伤相对于对产量的影响而言，是否能提供一种更可靠的病害严重程度评估方法。1996年和1997年，在田间小区中，使用叶片和豆荚评级（0至10级，对应0%至100%的受影响组织）对中度抗性品种NK S57 - 11和感病品种Buckshot 723的病害严重程度进行了评估。基于回归分析结果，随着病害严重程度的增加，每小区的豆荚数、种子数和种子重量均下降，而部分饱满豆荚的比例和百粒重不受影响。产量损失似乎主要是由于整个豆荚的损失。两个品种在1996年（r = 0.8343）和1997年（r = 0.5958）的叶片和豆荚病害严重程度评估呈正相关，这表明两种方法均可用于识别品种间的相对差异。然而，在低病害条件下，豆荚评估比叶片评估能解释更多的变异性。表现出中度至重度大豆丝核菌叶枯病症状的植株在收获时茎和豆荚仍保持绿色，这是成熟延迟的证据。
