Repeatability coefficient estimates and optimum number of harvests in graft/rootstock combinations for 'tahiti' acid lime

ABSTRACT Combining longitudinal data and statistical models from perennial crops enabled us to estimate the optimum number of measures (harvests), implying accurate discrimination of superior genotypes in those crops. Herein, the goal of this study was to determine the optimum number of harvests based on yield traits and recommend a superior graft/rootstock combination (GRC) for Citrus latifolia Tanaka. Twenty-four GRCs of 'Tahiti' acid lime were evaluated from July 2017 to August 2018 for fruit yield per plant (FYP), number of fruits per plant (NFP), and longitudinal (LFD) and transversal fruit diameter (TFD). The experimental design was a randomized complete block with 4 replications. The experimental unit consisted of three individuals, totalling 244 individuals. The GRCs were composed of (i) two hybrids that were used as rootstock, citrumelo ‘Swingle’ (Citrus paradisi x Poncirus trifoliata) and cintrandarin ‘Riverside’ (Citrus sunki x Poncirus trifoliata); and (ii) 12 different C. latifolia genotypes that were used as grafts: Bello Fruit, Eledio, Iconha, Itarana, Santa Rosa, Bearss lime, CNPMF 01, CNPMF 02, CNPMF 2001, CNPMF 5059, BRS Passos, and Persian 58. Mixed models were employed to estimate the variance components. The optimum number of harvests was determined based on selective efficiency values above 0.9. The estimated repeatability coefficients presented values of 0.14 (LFD), 0.16 (TFD), 0.36 (FYP), and 0.38 (NFD). Based on the results, four harvests were able to choose genotypes based on FYP and NFP, whereas LFD and TFD were considered inefficient traits for recommending superior GRCs.摘要：结合多年生作物的纵向数据与统计模型，本研究可估算最优测量次数（即采收次数），从而实现该类作物优异基因型的精准鉴别。本研究旨在基于产量性状确定最优采收次数，并为莱姆橘（Citrus latifolia Tanaka）推荐优异嫁接-砧木组合（graft/rootstock combination, GRC）。本研究以24份‘塔希提’酸橙嫁接-砧木组合为供试材料，于2017年7月至2018年8月间测定其单株果实产量（fruit yield per plant, FYP）、单株果实数（number of fruits per plant, NFP）、果实纵径（longitudinal fruit diameter, LFD）及果实横径（transversal fruit diameter, TFD）。试验采用完全随机区组设计，设置4次重复，试验单元为3株植株，共计244株供试材料。供试嫁接-砧木组合由两部分构成：（i）2份用作砧木的杂交材料——‘Swingle’柑桔柚杂种（Citrus paradisi × Poncirus trifoliata）与‘Riverside’香橙枳杂种（Citrus sunki × Poncirus trifoliata）；（ii）12份用作接穗的不同莱姆橘基因型，分别为Bello Fruit、Eledio、Iconha、Itarana、Santa Rosa、Bearss lime、CNPMF 01、CNPMF 02、CNPMF 2001、CNPMF 5059、BRS Passos及Persian 58。本研究采用混合模型估算方差组分，以选择效率值大于0.9为标准确定最优采收次数。经估算，各性状的重复力系数分别为：果实纵径（LFD）0.14、果实横径（TFD）0.16、单株果实产量（FYP）0.36及NFD 0.38。研究结果表明，基于单株果实产量（FYP）与单株果实数（NFP），仅需4次采收即可完成优异基因型的筛选；而果实纵径（LFD）与果实横径（TFD）并不适于作为筛选优异嫁接-砧木组合的有效性状。