United States Department of Agriculture-Agriculture Research Service, Fort Detrick, MD 21702, USA.
Phytopathology. 2012 Aug;102(8):761-8. doi: 10.1094/PHYTO-01-12-0011-R.
Although considerable information exists regarding the importance of moisture in the development of soybean rust, little is known about the influence of temperature. The purpose of our study was to determine whether temperature might be a significant limiting factor in the development of soybean rust in the southeastern United States. Soybean plants infected with Phakopsora pachyrhizi were incubated in temperature-controlled growth chambers simulating day and night diurnal temperature patterns representative of the southeastern United States during the growing season. At 3-day intervals beginning 12 days after inoculation, urediniospores were collected from each plant and counted. The highest numbers of urediniospores were produced when day temperatures peaked at 21 or 25°C and night temperatures dipped to 8 or 12°C. When day temperatures peaked at 29, 33, or 37°C for a minimum of 1 h/day, urediniospore production was reduced to 36, 19, and 0%, respectively, compared with urediniospore production at the optimum diurnal temperature conditions. Essentially, no lesions developed when the daily temperature high was 37°C or above. Temperature data obtained from the National Climatic Data Center showed that temperature highs during July and August in several southeastern states were too high for significant urediniospore production on 55 to 77% of days. The inhibition of temperature highs on soybean rust development in southeastern states not only limits disease locally but also has implications pertaining to spread of soybean rust into and development of disease in the major soybean-producing regions of the Midwestern and northern states. We concluded from our results that temperature highs common to southeastern states are a factor in the delay or absence of soybean rust in much of the United States.
虽然关于水分在大豆锈病发展中的重要性有相当多的信息，但对温度的影响知之甚少。我们研究的目的是确定温度是否可能是美国东南部大豆锈病发展的一个重要限制因素。感染 Phakopsora pachyrhizi 的大豆植株在温度控制的生长室中孵育，模拟美国东南部生长季节的昼夜温度模式。在接种后 12 天开始，每隔 3 天从每株植物上收集和计数夏孢子。当日最高温度达到 21 或 25°C 且夜间温度降至 8 或 12°C 时，产生的夏孢子数量最多。当日最高温度达到 29、33 或 37°C 且每天至少 1 小时时，与最适昼夜温度条件下的夏孢子产量相比，夏孢子产量分别减少了 36%、19%和 0%。当每日温度高达到 37°C 或以上时，基本上没有病变发展。从国家气候数据中心获得的温度数据表明，在东南部的几个州，7 月和 8 月的高温在 55%至 77%的天数里不利于大量产生夏孢子。温度升高对东南部大豆锈病发展的抑制不仅使局部疾病受到限制，而且还对大豆锈病向中西部和北部主要大豆产区的传播和发展产生影响。我们从研究结果中得出结论，东南各州常见的高温是美国大部分地区大豆锈病延迟或不存在的一个因素。
