直播稻田杂草稻灾害发生及生态型的演变特征OA北大核心CSTPCD

[Objective]Weedy rice poses a significant threat to rice production in direct-seeded rice fields,resulting in substantial yield losses.Analyzing the occurrence patterns,diversity changes,and genetic evolution of weedy rice populations in these fields is crucial for managing agricultural ecosystems effectively and preventing weedy rice disasters.[Methods]This study conducted a continuous three-year fixed-site survey of weedy rice populations in new direct-seeded rice field ecosystems.Through targeted sampling,phenotypic characterization,and population genetic structure analysis using liquid chip technology,we examined the scale of damage,ecological types,and genetic diversity evolution of weedy rice populations.[Results]In direct-seeded rice fields,the weedy rice population increased annually,with densities of 345.6 plants/m2,512.4 plants/m2,and 600.1 plants/m2,respectively.Phenotypic diversity showed a consistent upward trend,with Shannon-Wiener(H')indices of 0.530,0.762,and 0.852,and Simpson(D)indices of 0.340,0.227,and 0.164.Genetic diversity(Pi)initially increased and then declined over the three years,with values of 0.2097,0.2530,and 0.1493,respectively.At the population genetic structure level,both principal component analysis(PCA)and phylogenetic tree analysis consistently indicated that weedy rice was not directly related to locally cultivated rice.Weedy rice samples from different years were distributed across major clustering branches.Various types of weedy rice underwent natural selection due to the cold environment and competition with direct-seeded rice,leading to a survival-of-the-fittest scenario.This process results in rapid convergence,increased genetic diversity,alterations in population genetic structure,and the emergence of adaptive types.[Conclusion]Weedy rice invasion in direct-seeded rice fields leads to rapid population expansion and diversity increase,escalating the disaster index swiftly.Genetic diversity and population genetic structure are highly sensitive to selection pressure,suggesting that harmful adapted weedy rice types are established early in their invasion into direct-seeded rice field ecosystems.