Adhikari Tika B, Shrestha Anil, Basnyat Ram Chandra, Mew T W
Agriculture and Agri-Food Canada, Saskatoon Research Centre, 107 Science Place, Saskatoon, SK S7N 0X2, Canada.
Department of Plant Agriculture, University of Guelph, Ontario, N1G 2W1 Canada.
Plant Dis. 1999 Oct;83(10):896-901. doi: 10.1094/PDIS.1999.83.10.896.
The progress of bacterial blight epidemics, caused by Xanthomonas oryzae pv. oryzae, varies with environment. The irrigated lowland rice production environment in central Terai (plain) is less conducive to the disease than the irrigated lowland rice production environment in eastern Terai in Nepal. The effect of partial resistance on bacterial blight was studied in central Terai during the wet seasons of 1994, 1995, and 1996. Three partially resistant rice cultivars, Sabitri, Laxmi, and IR54 (possessing the Xa4 gene), and susceptible check IR24 were included in this study. Analysis of pooled data from the 3 years of experiments indicated that rice cultivars differed in resistance based on three epidemiological parameters: disease severity (DS), area under the disease progress curve (AUDPC), and rate of disease increase (r). Estimates of DS, AUDPC, and r were reduced and yield loss was negligible in the partially resistant cultivar Laxmi compared with the susceptible check IR24. IR54, which has partial resistance to X. oryzae pv. oryzae, also showed low DS, AUDPC, and r, which prevented yield loss due to bacterial blight. The locally adapted cultivar Sabitri showed intermediate estimates of DS, AUDPC, r, and yield loss. Earlier and more severe disease developed in the susceptible check IR24, resulting in a yield loss of 22%. Yield losses were mainly due to reductions in number of tillers, number of grains per panicle, and 1,000-grain weight. These data indicate that the use of rice cultivars with high levels of partial resistance will be an effective tool for the management of bacterial blight in central Terai and similar environments in Nepal.
由稻黄单胞菌稻致病变种引起的白叶枯病流行进程因环境而异。尼泊尔中部特赖（平原）的灌溉低地水稻生产环境比东部特赖的灌溉低地水稻生产环境更不利于该病发生。1994年、1995年和1996年雨季期间，在中部特赖研究了部分抗性对白叶枯病的影响。本研究纳入了三个部分抗性水稻品种Sabitri、Laxmi和IR54（携带Xa4基因）以及感病对照品种IR24。对3年试验的汇总数据分析表明，基于三个流行病学参数，即病情严重度（DS）、病害进展曲线下面积（AUDPC）和病害增加速率（r），各水稻品种在抗性方面存在差异。与感病对照品种IR24相比，部分抗性品种Laxmi的DS、AUDPC和r估计值降低，产量损失可忽略不计。对稻黄单胞菌稻致病变种具有部分抗性的IR54也表现出较低的DS、AUDPC和r，从而避免了因白叶枯病造成的产量损失。当地适应性品种Sabitri的DS、AUDPC、r和产量损失估计值处于中等水平。感病对照品种IR24发病更早且更严重，导致产量损失22%。产量损失主要是由于分蘖数、每穗粒数和千粒重的减少。这些数据表明，使用具有高度部分抗性的水稻品种将是尼泊尔中部特赖及类似环境中白叶枯病防治的有效手段。
