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为了探讨大叶小蘖对小麦稈锈病流行无关的原因,以大叶小蘖上的锈孢子接种小麦上,和 P.Elymina P.Pygmaea 的冬孢子接种大叶小蘖上,结果肯定大叶小蘖在自然条件下对当地小麦稈锈病流行无关。大叶小蘖是这两种杂草锈菌的锈孢子阶段寄主。大叶小蘖展叶时期的气候条件不利于小麦稈锈菌冬孢子发芽,这是它在自然条件下不起转主寄主作用的关键因素。在小蘖展叶盛期(最易感染时期)的5月中旬,平均气温适合小麦稈锈菌冬孢子发芽,但缺少必要的湿度条件。而在连雨潮湿天气,湿度条件虽然具备了,但温度又降得很低,这就使小麦稈锈菌冬孢子很难发芽,使小蘖错过了最易感染的机会,5月下旬以后,气温日渐增高,又超过了小麦稈锈菌参孢子发芽的最高温度,虽有充足的水分,冬孢子也很少发芽。此时小蘖陆续长出新梢,发出嫩叶,也不再被侵染了。三年来,在小蘖邻近麦地调查,和进行稈锈菌生理小种分析结果,小麦稈锈菌不通过大叶小蘖产生多种生理小种。冬孢子发芽试验证明,在斗沟子各处散乱的麦稈上的小麦稈锈菌冬孢子,到5月中旬已正常成熟,发芽率很高。只要有充足的水分,在9°—21℃温度范围内,小麦稈锈菌冬孢子发芽很好,且长小孢子;而在9℃以下或22℃以上,冬孢子很少发芽。
In order to investigate the reason why the large-leaved tiller has nothing to do with the epidemic of wheat stem rust, we inoculated the wheat with the spores on the small tiller, and the small tiller on the large-leaf tiller with P. elymina P. Pygmaea. Tillers have no correlation with the prevalence of local wheat stem rust under natural conditions. Large-leaved tillers are the rust spore stage hosts of both weeds. The climatic conditions during the leaf-setting period of large-leaved small tillers are not conducive to the spore-forming of wheat spore rust, which is the key factor that does not play a role as the main host in natural conditions. In mid-May of mid-May, the average temperature was suitable for teliospore germination of wheat straw rust, but lacking the necessary humidity conditions. In the even wet weather, although the humidity conditions are available, but the temperature dropped very low, which makes the winter wheat spore rust hard stem spores, so that small tillers missed the most vulnerable to infection, late May, Increasing temperature, but also exceeded the maximum temperature of spore germination of wheat straw rust spores, although sufficient water, winter spores rarely sprout. Small tillers at this time one after another to grow new shoots, issued young leaves, no longer be infected. In the past three years, surveys of wheat fields near small tillers and the analysis of physiological races of Stem Blight have shown that Wheat Stem Rust does not produce a variety of physiological races through Larvae. Winter spore germination test proved that scattered throughout the fighting Dugou wheat straw rust on wheat stem winter spores, by mid-May has been normal maturation, germination rate is high. As long as there is sufficient moisture, the teliospores of wheat straw rust germinate very well and microspore grows within the temperature range of 9 ° -21 ℃, whereas the teliospores rarely sprout below 9 ℃ or above 22 ℃.