Effective population size and genetic gain expected in a population of Coffea canephora

Abstract This work aimed to study the effective population size and genetic gain in a population of robusta coffee (Coffea canephora Pierre) and verify the possibility of using recurrent selection. The experiment comprised 25 treatments, consisting of 21 C. canephora progenies and four C. arabica (cultivars) grown in Brazil. The experimental design was a 5x5 quadruple balanced lattice, with 24 replications, with one plant per plot. Six harvests were performed in each plant. Statistical analysis was carried out using the mixed model methodology. The analysis showed high additive genetic variability, and the magnitude of the additive components prevailed over that of the dominance components. These facts revealed the plant population liability to undergo recurrent selection, whose expected genetic gains were high. Results suggest that the effective population size and inbreeding degree throughout recurrent selection cycles be monitored. During selective cycles, cloning with weak selection is required due to few progenies.

摘要 本研究旨在探究罗布斯塔咖啡（Coffea canephora Pierre）种群的有效种群大小（effective population size）与遗传增益（genetic gain），并验证应用轮回选择（recurrent selection）的可行性。试验共设置25个处理，包含21份刚果咖啡（Coffea canephora Pierre）家系与4份阿拉伯咖啡（Coffea arabica）栽培品种，种植于巴西境内。试验采用5×5四倍平衡格子设计，共24次重复，每小区定植1株植株。每株植株完成6次采收。统计分析采用混合模型方法（mixed model methodology）。分析结果显示，该种群存在较高的加性遗传变异（additive genetic variability），且加性组分的效应量显著优于显性组分（dominance components）。上述结果表明该植物种群适用于轮回选择，且预期遗传增益较高。研究结果提示，需对轮回选择各周期中的有效种群大小及近交程度（inbreeding degree）进行监测。鉴于家系数量较少，在选择周期内需采用弱选择配合克隆的育种策略。