The definition of efficient selection methods for biomass yield of alfalfa and other open-pollinated forage crops has lagged behind, despite its crucial importance for breeders. This study, performed in northern Italy, aimed to compare nine breeding schemes encompassing the evaluation of replicated clones and half-sib (HS), first selfing generation (S₁) or second selfing generation (S₂) families without or with within-family selection. The comparison was based on actual gains for dry-matter yield over 43 mo and final plant survival across irrigated and rainfed cropping of advanced generation synthetics (Syn-3) built from 12 selected parents. The study envisaged biomass yield selection over 31 mo under dense planting among 125 S₀ plants and/or their progenies, after a stage of stratified mass selection which acted as a benchmark for genetic gains and whose genetic progress over the original genetic base was concurrently assessed. Half-sib progeny-based selection exhibited highest genetic gains with respect to unit time and return on yearly investment for direct costs for both biomass yield and crop persistence. Among-and-within-HS family selection ranked second, and S₁ progeny-based selection ranked third, for yield gains, whereas three schemes implying two selfing generations were valuable for improving persistence but not yield. The initial stage of stratified mass selection was time- and cost-efficient for improving yield but not persistence. We provided information also on self-fertility and inbreeding depression variation across selfing generations, genetic variation of clonal, HS, S₁ and S₂ material, and consistency of S₀ parent value across different types of material. Our results may have implications for field-based and genomic selection.

中文翻译：

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基于实际生物量产量增益的九种苜蓿育种方案的比较

尽管对育种者至关重要，但对苜蓿和其他开放授粉草料作物生物量产量的有效选择方法的定义已经落后。这项在意大利北部进行的研究旨在比较九种育种计划，包括对无或有家庭内的复制克隆和半同胞 (HS)、第一代 (S ₁ ) 或第二代 (S ₂ ) 家庭的评估选择。比较是基于 43 个月内干物质产量的实际收益以及灌溉和雨育种植的先进合成作物 (Syn-3) 的最终植物存活率，这些作物由 12 个选定的亲本构建而成。该研究设想在 125 S ₀之间密集种植下超过 31 个月的生物量产量选择植物和/或其后代，在作为遗传增益基准的分层质量选择阶段之后，同时评估其在原始遗传基础上的遗传进展。基于半同胞后代的选择在单位时间和生物量产量和作物持久性的直接成本的年度投资回报方面表现出最高的遗传收益。HS家庭选择排名第二，S ₁基于后代的选择在产量增加方面排名第三，而暗示两代自交的三个方案对于提高持久性很有价值，但对提高产量没有价值。分层质量选择的初始阶段对提高产量具有时间和成本效益，但不是持久性。我们还提供了关于自交世代之间的自交和近交衰退变异、克隆、HS、S ₁和 S ₂材料的遗传变异以及不同类型材料之间S ₀亲本值的一致性的信息。我们的结果可能对基于田间的选择和基因组选择有影响。