Seedling Establishment Rate of Double-cropping and Direct-seeded Rice under Submergence in South China:Germplasm Screening and Comparative Analysis
The widely used rice varieties(parents)in the rice-growing area of South China were used as test materials and the field direct seeding and flooding seedling emergence tests were conducted in both early and late seasons,respectively,in South China.The aim was to identify and screen out germplasm with higher rate of seedling establishment under flooding and submergence conditions(under the condition of water depth of 6 cm),and provide material support for the development of new rice varieties suitable for direct seeding under natural conditions in South China.The results showed that the seedling establishment rate under flooding and submergence conditions in the early season was significantly higher than that in the late season,and there was no significant correlation between the rates of seedling establishment in the early and late seasons(R2=-0.1253).In the early season,the rates of seedling establishment of'Francis','starbonett99','Runfeng B','Kasalath',and'Yuekang 1614',were the highest five materials,up to 65.0％to 76.5％.Cluster analysis grouped these five materials into the same cluster I.In the late season,the rates of seedling establishment of'Yujingruanzhan'and'Conventional Rice 5'were the highest ones,but only accounted for 42.5％and 39.5％,respectively,and they were also grouped into the same cluster.This indicates that due to different climatic conditions in the early and late rice-growing seasons in South China,different types of germplasm materials with high seedling establishment rate under flooding and submergence conditions should be selected for the breeding of new direct-seeded rice varieties.
ricegermplasm screeningrate of seedling establishmentsubmergencedirect-seeded riceSouth China
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