Abstract Plant breeding is one of the key strategies for further enhancement of crop yields; however, effective breeding strategies require phenotypic characterisation of the available germplasm. This study sought to characterise the phenotypic expression of fourteen crop traits related to phenology, plant architecture, and yield in a panel of 40 cultivars selected to represent the phenotypic variability present in Italian rice germplasm during a two-season field experiment. The observed range of phenotypic variation was high for many traits (coefficients of variation ranging from 5.9% to 45.4%) including yield (mean: 6.47 t ha−1; CV: 15.4 %; min: 2.19 t ha−1; max: 8.95 t ha−1), and multiple strong associations emerged in all the analysed traits. Cluster analysis extracted three groups of genotypes characterised by alternative yield strategies, i.e. “high-tillering”, “early maturing”, and “increased source-sink”. Our findings highlight that rice yield decrease when one strategy is overemphasised. In contrast, the highest-yielding genotypes have a balanced ratio between sink and source organs, along with a proportional duration of vegetative and reproductive phases. This study depicts the phenotypic variability in Italian rice cultivars and proposes a novel classification based on yield-related traits which could be of use in multiple rice breeding applications.

中文翻译：

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意大利水稻种质的表型变异

摘要 植物育种是进一步提高作物产量的关键策略之一；然而，有效的育种策略需要对可用种质进行表型表征。本研究旨在表征与物候学、植物结构和产量相关的 14 种作物性状的表型表达，这些性状由 40 个品种组成，这些品种被选为代表在两季田间试验期间意大利水稻种质中存在的表型变异性。观察到的许多性状的表型变异范围很大（变异系数范围从 5.9% 到 45.4%），包括产量（平均值：6.47 t ha-1；CV：15.4 %；最小值：2.19 t ha-1；最大值：8.95 t ha-1)，并且在所有分析的特征中都出现了多个强关联。聚类分析提取了三组以替代产量策略为特征的基因型，即。e. “高分蘖”、“早熟”和“增源汇”。我们的研究结果强调，当过分强调一种策略时，水稻产量会下降。相比之下，产量最高的基因型在汇器官和源器官之间具有平衡的比例，以及营养和繁殖阶段的成比例持续时间。本研究描述了意大利水稻品种的表型变异性，并提出了一种基于产量相关性状的新分类，可用于多种水稻育种应用。