Abstract Earlier investigations on the possible advantages of heterogeneous inbred crops in terms of performance, adaptability and yield stability focused mainly on small-grain cereals. This study provides an unprecedented assessment of these advantages for an inbred forage crop, namely, subterranean clover (Trifolium subterraneum L.). Pure lines of the subspecies subterraneum (S) and brachycalycinum (B) featuring contrasting phenology that were collected from each of two climatically-contrasting locations were compared with their intra-subspecies 2- and 4-component mixtures and inter-subspecies 4- and 8-component mixtures. The comparison encompassed biomass yield, seed production and seedling regeneration measured over two seasons in four managed environments with contrasting soil types and drought stress levels. Compared with the mean value of component lines, intra-subspecies mixtures of the subspecies with greater phenological diversity, i.e., S, exhibited greater biomass, seed yield and seedling regeneration across environments, whereas intra-subspecies mixtures of B or inter-subspecies mixtures with 4-components exhibited a biomass yield advantage only. Diversity maximisation by the 8-component mixture failed to out-yield the mean of its component lines for any trait. On average, mixtures diplayed distinctly greater stability of biomass yield and seedling regeneration performance as measured by low absolute values of the first entry × environment interaction principal component axis compared to pure lines. Advantages were similar for the two subspecies and tended to increase with increasing mixture complexity. While S mixtures could capitalise on complementary responses of their component lines to different drought stress levels, inter-subspecies mixtures could also exploit complementary responses to contrasting soil types. The comparison among best-performing entries within each plant material highlighted the value of a B 2-component mixture, which displayed a slight, non-significant penalty of biomass yield, nearly identical seed yield and seedling regeneration, and distinctly greater stability of performance for all traits, compared to the pure line with greatest biomass yield.

中文翻译：

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在对比鲜明的地中海环境中，不同复杂度的地下三叶草纯线条和线条混合物的性能和适应性

摘要 早先对异种近交作物在性能、适应性和产量稳定性方面的可能优势的研究主要集中在小粒谷物上。这项研究为近交牧草作物，即地下三叶草 (Trifolium subterraneum L.) 提供了对这些优势的前所未有的评估。亚种 subterraneum (S) 和 brachycalycinum (B) 的纯品系具有对比物候的特征，从两个气候相反的位置中的每一个收集到的，与它们的亚种内 2 和 4 组分混合物以及亚种间 4 和 8 进行了比较- 组分混合物。比较包括在四个管理环境中两个季节测量的生物量产量、种子产量和幼苗再生，这些环境具有对比的土壤类型和干旱胁迫水平。与成分系的平均值相比，具有更大物候多样性的亚种的亚种内混合物，即 S，表现出更大的生物量、种子产量和跨环境的幼苗再生，而 B 的亚种内混合物或亚种间混合物与4-组分仅表现出生物量产量优势。8 组分混合物的多样性最大化未能超过其任何特征的组分线的平均值。平均而言，与纯品系相比，混合物表现出明显更高的生物质产量稳定性和幼苗再生性能，这是通过第一项×环境相互作用主成分轴的低绝对值来衡量的。两个亚种的优势相似，并且随着混合物复杂性的增加而增加。虽然 S 混合物可以利用其组成线对不同干旱胁迫水平的互补反应，但亚种间混合物也可以利用对对比土壤类型的互补反应。每种植物材料中表现最佳的条目之间的比较突出了 B 2 组分混合物的价值，它显示了生物量产量的轻微、非显着损失、几乎相同的种子产量和幼苗再生，以及明显更高的性能稳定性所有性状，与具有最大生物量产量的纯系相比。