Testers in supersweet corn lines

ABSTRACT: The purpose of this study was to evaluate the discriminatory capacity of tester lines for tropical corn lines converted to supersweet shrunken (sh2) gene, for the development of hybrids adapted to tropical conditions. Lines were used as female parents in crosses with three testers: open-pollinated mixed variety; supersweet line L4; supersweet commercial hybrid Tropical Plus. Four trials were carried out to evaluate topcrosses in Maringá - PR e Sabáudia - PR, Brazil in the main growing season of 2015/16. The following traits were evaluated: total ear weight (TEW, in kg), commercial ear weight (CEW, in kg) and total soluble solids (TSS, in °Brix). The GCA estimates for TEW and CEW were highest for L4. The lines Balu-114 and UEM-25 were selected based on the effects of g ̂ ifor the traits studied and should be used in the establishment of base populations for the breeding of superior lines. The s ̂ ijvalue for TEW was highest for cross BALU-182 x Tropical, while for CEW was the highest value for cross BALU-94 x Mista.摘要：本研究旨在评估转育了超甜皱缩（shrunken, sh2）基因的热带玉米自交系的测验种鉴别能力，以培育适配热带种植环境的杂交品种。试验以3个测验种作为父本，与目标自交系组配测交组合：开放授粉混合品种、超甜自交系L4、超甜商用杂交种Tropical Plus。2015/16年度主茬种植季，在巴西巴拉那州马林加（Maringá - PR）与萨巴乌迪亚（Sabáudia - PR）共开展4项顶交种评价试验。本次试验测定的性状包括果穗总重量（total ear weight, TEW，单位：kg）、商品果穗重量（commercial ear weight, CEW，单位：kg）及可溶性固形物总量（total soluble solids, TSS，单位：°Brix）。果穗总重量与商品果穗重量的一般配合力（general combining ability, GCA）估计值以自交系L4最高。基于各目标性状的估计一般配合力效应（ĝ_i），筛选出自交系Balu-114与UEM-25，可用于构建选育优良自交系的基础群体。果穗总重量的特殊配合力效应（ŝ_ij）以组合BALU-182 × Tropical最高，而商品果穗重量的特殊配合力效应以组合BALU-94 × Mista最高。