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：本研究的开展源于当前针对本试验涉及作物的锈病抗性遗传调控机制及关键经济性状相关信息的匮乏。本研究以巴西里约热内卢州的两个代表性试点为试验场地，采用部分双列杂交（partial diallel cross）设计，对16个爆裂玉米自交系与杂交种的配合力进行评价，最终获得40个单交种。试验采用完全随机区组设计，设置4次重复，于自然锈病侵染条件下开展，以调查全株南方锈病病情指数（SSW）、果穗位叶南方锈病病情指数（SFPE），以及核心关注的形态农艺性状：籽粒产量（grain yield, GY）与膨化倍数（popping expansion, PE）。遗传效应分析表明，膨化倍数（PE）的遗传调控以加性基因效应为主，而籽粒产量（GY）则以非加性基因效应占优；不过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在所有供试性状上均表现出适宜的特殊配合力（specific combining ability, SCA），因此具备选育优良基因型的潜力。自交系L80、L76与L77在SSW与SFPE上均呈现负向一般配合力（general combining ability, GCA）；自交系P10在GY与PE上则表现出高正向一般配合力（GCA）。