人工接种测定水稻干尖线虫在水稻上的病害发展动态

Study on Dynamic Development of Aphelenchoides besseyi on Rice Plant by Artificial Inoculations in Greenhouse

【目的】探讨近年来江苏水稻生产上的重要病害水稻—"小穗头"和水稻干尖线虫间的相互关系。【方法】在水稻"小穗头"上分离出干尖线虫,经人工培养,在温室中接种到镇稻2号和武运粳7号的芽鞘部和叶鞘部,通过测定发病程度,稻谷饱满度,谷粒中线虫虫量和线虫死亡率等指标来确定对"小穗头"形成以及对水稻生长发育的影响。【结果】镇稻2号"小穗头"与健康稻穗相比水稻株高下降6.7%、稻穗长度减少16.4%、稻谷粒数下降13.5%。在开花期之前,线虫主要分布于叶鞘部和生长点周围,虫量增加40%;花期后,线虫主要分布于稻穗上并且虫量增幅达90.8%。饱粒种子中带虫率、线虫虫量最高,空粒种子则最低。线虫死亡率在胚乳发育正常的种子中要比胚乳发育不正常的种子低。【结论】水稻干尖线虫是造成水稻"小穗头"症状的病原。武运粳7号仅表现"小穗头"而无叶片干尖症状,说明该现象是干尖线虫在水稻上呈现的新症状。

【Objective】 An experiment was carried out to study the relationship between Aphelenchoides besseyi and the symptoms of small grains and erect panicles, a severe rice disease in Jiangsu province, China. 【Method】A. besseyi was extracted from small grains and erect panicles and cultured artificially, then inoculated into bud and leaf sheaths of seedlings of two Oryza sativa cultivars, namely Zhendao No.2 and Wuyunjing No.7 in a greenhouse. The effect on rice growth, in particular the small grains and erect panicles, was revealed by the extent of the disease, seed expansion stages, nematode load and nematode mortality. 【Result】In contrast to healthy seedlings, the height, length and the numbers of spikelets of unhealthy panicles of Zhendao No.2 decreased by 6.7%, 16.4%, 13.5%, respectively. Before anthesis, nematodes were attracted to the leaf sheath and apical meristem, nematode load increased by 40%; after anthesis nematodes occurred in spikelets principally and the number increased by 90.8%.The percentage of infected seeds and nematode load were highest in plump seeds and lowest in empty seeds. Nematode mortality on grain with normal endosperm was lower than seeds with abnormal endosperm. 【Conclusion】Results indicated that A. besseyi was the pathogen in rice with the symptoms of small grains and erect panicles. Wuyunjing No.7 manifests only small grains and erect panicles but not symptom of leaf white-tip. These symptoms of small grains and erect panicles are new symptom records for disease caused by A. besseyi on rice.