Seasonal Fluctuations in Numbers of Larvae of the Cereal Cyst Nematode (Het'Erodera Avenae) and of Pratylenchus Minyus and T'Ylenchorhynchus Brevidens in Soil
Seasonal Fluctuations in Numbers of Larvae of the Cereal Cyst Nematode (Het'Erodera Avenae) and of Pratylenchus Minyus and T'Ylenchorhynchus Brevidens in Soil
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DOI：
10.1163/187529270x00018
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发表时间：
1970
期刊：
影响因子：
--
通讯作者：
J. Meagher
中科院分区：
文献类型：
--
作者：
J. Meagher
季节性出现的H.连续3年对田间麦长管蚜幼虫进行了研究。幼虫数量最高，在深秋和冬季时，土壤水分和土壤温度的水平有利于出现。秋季降雨量少可能会延迟出苗。在温室实验中，土壤从一个领域自然感染Heterodera avenae，Pratylenchus minyus和Tylenchorhynchus brevidens暴露于五个水分制度。在田间持水量的土壤中，H. 5个月后，燕麦幼虫和少量卵存活。在秋季和冬季，幼虫的出现是良好的土壤始终保持在60%的田间持水量，并进一步增加土壤进行干湿循环。在春末和夏季，土壤中没有幼虫。孵化和出现的模式解释了线虫病的严重程度增加，秋季降雨量高。虽然澳大利亚和北方的季节相反，但幼虫在一年中大约相同的月份出现。出现后，似乎在秋季温度降低。在澳大利亚，这可能是一样重要的最佳出现足够的土壤水分，但没有证据表明，一个非常低的温度要求孵化前。在接下来的秋天，孵化卵留在包囊表现出休眠或滞育。在空气干燥的土壤中，鸡蛋在储存13个月后几乎没有活力损失，土壤湿润后出苗良好。这与欧洲的观察相反。P.minyus和T.短齿藓在干燥土壤中表现出良好的生存能力，约50%的初始种群分别存活了15个月和9个月。
The seasonal emergence of H. avenae larvae in the field was studied for 3 consecutive years. Larval numbers were highest during late autumn and winter when levels of soil moisture and soil temperature were favourable for emergence. Low rainfall in the autumn may delay emergence. In a glasshouse experiment, soil from a field naturally infested with Heterodera avenae, Pratylenchus minyus and Tylenchorhynchus brevidens was exposed to five moisture regimes. In soil held at field capacity there was a low emergence of H. avenae larvae and few eggs were viable after 5 months. In autumn and winter, larval emergence was good in soil constantly maintained at 60% field capacity, and was further increased in soil subjected to wetting and drying cycles. Larvae were absent from the soil in late spring and summer. The patterns of hatching and emergence explain the increased severity of nematode disease following high autumn rainfall. Although the seasons in Australia and Northern Europe are opposite, larvae emerge during, approximately, the same months of the year. Emergence appeared to follow a lowering of temperature in autumn. In Australia, this may be as important for optimum emergence as adequate soil moisture, but there is no evidence for a very low temperature requirement prior to hatching. In the following autumn, hatch from eggs remaining in cysts demonstrated dormancy or diapause. In air-dry soil, eggs showed little loss of viability after thirteen months storage and good emergence followed soil wetting. This contrasts with European observations. P. minyus and, to a lesser extent, T. brevidens showed a good capacity to survive in dry soil and about 50% of the initial populations survived for fifteen and nine months respectively.