The combining ability of popcorn S7 lines for Puccinia polysora resistance purposes

ABSTRACT The present study resulted from the lack of information on the genotypic expression ruling the resistance to rust and on the main traits of economic importance to the herein addressed crop. The combining ability of 16 popcorn lines and hybrids was assessed in partial diallel cross in two representative locations in Rio de Janeiro State, Brazil, where forty simple hybrids were obtained. The experiments followed a completely randomized block design with four repetitions and were conducted under natural infestation conditions in order to test the southern rust severity in the entire plant (SSW) and in the leaf of the first ear (SFPE), as well as the morpho-agronomic traits of greater interest: grain yield (GY) and popping expansion (PE). Additive gene effects prevailed in PE and the non-additive ones stood out in GY; however, both gene effects were important to the southern rust resistance characteristics (SSW and SFPE). Hybrids L65 × P10 and P7 × L70 presented appropriate specific combining ability (SCA) values in all traits; therefore, they were promising for the selection of superior genotypes. Lines L80, L76 and L77 expressed negative general combining ability (GCA) values in SSW and SFPE; line P10 recorded high and positiveGCA values in GY and PE.

摘要：本研究缘于当前针对本文所研究作物的抗锈病遗传调控机制及重要经济性状相关信息的匮乏。本研究在巴西里约热内卢州的两个代表性试点开展，采用部分双列杂交设计对16份爆裂玉米自交系与杂交种的配合力进行评估，共获得40个单交种。试验采用完全随机区组设计，设置4次重复，在自然侵染发病条件下进行，以测定全株南方锈病病情严重度（Southern Rust Severity on Whole plant, SSW）与第一果穗叶片南方锈病病情严重度（Southern Rust Severity on First Ear Leaf, SFPE），同时测定关键形态农艺性状：籽粒产量（Grain Yield, GY）与膨化体积（Popping Expansion, PE）。研究结果表明，加性基因效应对膨化体积（PE）的遗传调控占主导地位，而非加性基因效应在籽粒产量（GY）的遗传调控中更为突出；但两类基因效应对南方锈病抗性性状（SSW与SFPE）均具有重要作用。杂交组合L65×P10与P7×L70在所有待测性状上均表现出适宜的特殊配合力（Specific Combining Ability, SCA）值，因此在优良基因型选育中具备应用潜力。自交系L80、L76与L77在SSW与SFPE上呈现负值的一般配合力（General Combining Ability, GCA）；自交系P10在籽粒产量（GY）与膨化体积（PE）上表现出较高的正向一般配合力（GCA）。