广西热区晚稻田稗草种类及其分布特点

【目的】明确广西热区晚稻田发生危害的稗草种类及其地域分布特点，为广西稗草的防控及稗草生物学、生态学研究提供基础数据和参考。【方法】以稻田稗草为对象，于2019年10月和2020年10月采用五点取样法对处于热带季风气候区的南宁、北海、钦州、梧州、贵港、玉林、百色和崇左市晚稻田进行田间调查及采样，共112个调查点672个小区田块；采用七级目测法调查每个样点的稻田稗草发生情况；运用Levins方法中的Shannon-Wiener生态位宽度及Pianka生态位重叠值分析稻田稗草的生态位动态。【结果】广西热区晚稻田主要有孔雀稗、硬稃稗、长芒稗、西来稗、光头稗、稗、无芒稗、短芒稗和细叶旱稗等9种稗草，其中无芒稗的发生频度最大，为98.21%，其次为西来稗，发生频度为93.75%，长芒稗、硬稃稗和光头稗的发生频度较小，均低于40.00%；百色、钦州和梧州以无芒稗为优势种，北海、崇左、贵港、南宁和玉林等以西来稗为优势种；9种稗草中，以无芒稗的生态位宽度最大，为2.847，其次是西来稗，生态位宽度为2.614；稗与孔雀稗为最大生态位重叠值物种对，光头稗与硬稃稗为最小生态位重叠值物种对，光头稗与其他物种的生态位重叠值普遍较低。【结论】广西热区晚稻田稗草种类丰富，且不同区域稻田的优势稗草种类不同。生产中应针对不同种类稗草采取针性防控措施。

Distribution characteristics of Echinocloa species in late rice fields in tropical areas of Guangxi

【Objective】In order to study the distribution patterns of Echinocloa species in late rice fields in tropical areas of Guangxi and provide basic data for the control of barnyard grass, biology and ecology research on barnyard grass.【Method】Barnyard grass was the objective.Barnyard grass in the laterice fields of which located in the tropical region such as Nanning, Beihai, Qinzhou, Wuzhou, Guigang, Yulin, Baise and Chongzuo were investigated and sampled with the five point sampling method in October, 2019 and October, 2020.There were 112 investigation points and 672 plots.The occurrence of barnyard grass was surveyed by seven grade visual method on each point.The Shannon-Wiener niche width and Pianka niche overlap value in the Levins method were used to analyze the niche dynamics of barnyard grass in paddy field.【Result】The results showed that nine species of Echinocloa species were observed in late rice fields of Guangxi, they were E.cruspavonis, E.glabrescens, E.caudata, E.crusgalli var .zelayensis, E.colonum, E.glabrescens, E.crusgalli var .mitis, E.crusgalli var .Breviseta and E.crusgalli var .praticola. The occorrence frequency of E.crusgalli var .mitis was the highest(98.21%), followed by E.crusgalli var .zelayensis(93.75%), and those of E.caudata, E.glabrescens and E.colonum were low, which were all lower than 40.00%.In Baise, Qinzhou and Wuzhou, E.crusgalli var.mitis was mono-dominant among Echinocloa species on rice fields, while in Beihai, Chongzuo, Guigang, Nanning and Yulin, E.crusgalli var. zelayensis was dominant species.Among the nine Echinocloa species observed, E.crusgalli var.mitis showed the largest niche breadth(2.847), followed by E.crusgalli var.zelayensis(2.614).Niche overlaps between E.crusgalli and E.cruspavonis were the highest, that between E.colonum and E.glabrescens were the lowest, those between E.colonum and other species were low.【Conclusion】Echinocloa species in late rice fields of Guangxi are abundant, and the dominant species of barnyard grass are different in different rice fields.Specific control measures should be taken for different species of barnyard grass in production.