Selection of superior clones in sugarcane (Saccharum spp.) breeding programs follows a multistage process, starting in the first stage with selection of seedlings grown from seeds obtained from crosses. Effective selection of seedlings is important but notoriously difficult. Selection validity is affected by experimental error variation and interplant competition effects and is also complicated by the need to consider many different traits that affect economic value of cultivars (e.g., cane yield, sugar content, fiber content, disease resistance, etc.). In this study, we developed an optimized protocol for selection of sugarcane seedlings that balances the desire to maximize genetic gains but also be cost and labor efficient. A population of seedlings in commercial sugarcane breeding programs was first evaluated in a field trial (Stage 1). A subset of the population was then taken at random and grown in a subsequent trial (Stage 2) for evaluation in small plots. Minor modifications to application of the complete selection index that would greatly reduce labor requirements but have only a small impact on reducing genetic gains were then explored, to identify optimal selection protocols for routine application in commercial breeding programs. A procedure is recommended for routine selection of seedlings that involves (a) selection of families based on an index of four traits (stalk diameter, stalk height, trashiness, and pith rating, all derived from measurements of a small sample of seedlings in each family), followed by (b) sequential measurement and culling of individual seedlings in each selected family based on (in order) trashiness, stalk diameter, and pith rating.

中文翻译：

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优化甘蔗幼苗选择指标

甘蔗（Saccharum spp）优良无性系的选择.) 育种计划遵循一个多阶段过程，从第一阶段开始，选择从杂交获得的种子中生长的幼苗。有效地选择幼苗很重要，但也是出了名的困难。选择有效性受实验误差变异和植物间竞争效应的影响，并且由于需要考虑影响栽培品种经济价值的许多不同性状（例如，甘蔗产量、糖含量、纤维含量、抗病性等）而变得复杂。在这项研究中，我们开发了一个优化的甘蔗幼苗选择方案，该方案平衡了最大限度地提高遗传收益的愿望，同时也具有成本和劳动力效率。商业甘蔗育种计划中的幼苗群体首先在田间试验中进行评估（第一阶段）。然后随机抽取人口的一个子集，并在随后的试验（第 2 阶段）中生长以在小块中进行评估。然后探索了对完整选择指数应用的微小修改，这将大大减少劳动力需求，但对减少遗传收益只有很小的影响，以确定商业育种计划中常规应用的最佳选择方案。推荐的常规幼苗选择程序包括 (a) 根据四个性状指数（茎直径、茎高、杂度和髓核等级，所有这些都来自对每个家庭中的小样本幼苗的测量）来选择科)，然后是 (b) 根据（按顺序）垃圾性、茎直径和髓等级对每个选定家庭中的单个幼苗进行连续测量和剔除。