Abstract Early flooding after direct seeding induces anaerobic condition during germination or anaerobic germination (AG), which severely reduces crop establishment in both rainfed and irrigated areas. Seeds germinating in flooded soils could encounter hypoxia or even anoxia in severe cases, and this hinders germination and seedling growth. The study evaluated the effects of incorporating two major QTLs, AG1 and AG2, associated with tolerance of flooding during germination into the background of two popular rice varieties and assessed their interactive effects on enhancing crop establishment, and subsequent growth, grain yield and quality under direct seeded rice (DSR) system. Elite near-isogenic lines incorporating QTLs of major effects on AG tolerance (AG1, AG2 and AG1 + AG2) in the backgrounds of the popular varieties PSBRc82 (PSBRc82-AG1, PSBRc82-AG2, PSBRc82-AG1-AG2) and Ciherang-Sub1 (Ciherang-Sub1-AG1, Ciherang-Sub1-AG2, Ciherang-Sub1-AG1-AG2), along with the donors Kho Hlan On (KHN for AG1) and Ma-Zhan Red (MZR, AG2) and the recipients PSBRc82 and Ciherang-Sub1 were grown either under saturated soils or flooded with 3−5 cm water depth immediately after dry seeding. Flooding substantially reduced seedling emergence, survival, plant biomass, grain yield and yield components across genotypes. The reduction in yield was more drastic in the sensitive genotypes. The significant decline in grain yield was mainly attributed to reductions in number of panicle per unit area. The AG1, AG2 QTLs are effective in conferring tolerance of early flooding during germination. AG1 and AG2 introgression lines showed a yield advantage of up to 2.8 t ha−1, under early flooding compared with their recurrent parents. Apparently, introgression of AG1 and AG2 QTLs did not have any negative impact on performance under saturated (control) and flooded conditions with respect to seedling emergence, growth, and yield, though with effect on chalkiness in some backgrounds, which warrant further studies.

中文翻译：

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淹水条件下直播水稻系统AG1和AG2 QTLs基因渗入系的生长、生产力和籽粒品质

摘要 直播后过早淹水会在发芽或厌氧发芽（AG）期间诱导厌氧条件，这严重减少了雨育和灌溉地区的作物生长。种子在淹水土壤中发芽，严重时会遇到缺氧甚至缺氧，阻碍发芽和幼苗生长。该研究评估了将两个主要 QTL AG1 和 AG2 与发芽期间耐涝相关的影响纳入两个流行水稻品种的背景中，并评估了它们对促进作物生长、随后的生长、粮食产量和质量的交互作用。种稻（DSR）系统。在流行品种 PSBRc82 (PSBRc82-AG1, PSBRc82-AG2、PSBRc82-AG1-AG2）和 Ciherang-Sub1（Ciherang-Sub1-AG1、Ciherang-Sub1-AG2、Ciherang-Sub1-AG1-AG2），以及捐助者 Kho Hlan On（KHN 代表 AG1）和 Ma -Zhan Red (MZR, AG2) 和接受者 PSBRc82 和 Ciherang-Sub1 要么在饱和土壤下生长，要么在干播后立即用 3-5 cm 水深淹没。洪水大大减少了不同基因型的幼苗出苗、存活、植物生物量、谷物产量和产量成分。在敏感基因型中，产量的降低更为剧烈。粮食产量显着下降的主要原因是单位面积穗数减少。AG1、AG2 QTL 可有效赋予萌发期间早期洪水的耐受性。AG1 和 AG2 基因渗入系显示出高达 2.8 t ha-1 的产量优势，与他们经常出现的父母相比，在早期的洪水中。显然，AG1 和 AG2 QTL 的基因渗入对饱和（对照）和淹水条件下的幼苗出苗、生长和产量没有任何负面影响，尽管在某些背景下对垩白有影响，这值得进一步研究。