Selection of parents for low nitrogen stress through the combining ability of maize partially inbred lines

ABSTRACT. The objective of this work was to estimate the general combining ability of partially inbred lines under high and low nitrogen (N) conditions and to select promising lines to obtain high yields for both conditions. Fifty-five partially inbred S1 progenies were evaluated using the top-cross method, where the lines were crossed with two testers. The 110 top-cross hybrids were evaluated for grain yield during the off-season of 2012 at two sites in the Brazilian Midwest. Partial diallel analysis was performed with the adjusted means of each of the individual analyses of the top crosses. The combining ability of partially inbred lines and testers as well as their interaction with N levels, was estimated for each site. The coefficient of concordance among 15 partially inbred lines selected by the highest general combining ability estimates for each N level was 0.60. The S1 lines 39, 11, 41, 55, 38, 37, 6, 8, and 14 were selected at both N levels. This indicates that these lines can be used to identify ideal hybrids for growing in the off-season in the Brazilian Midwest.

摘要
本研究旨在评估部分自交系在高、低氮（nitrogen, N）条件下的一般配合力（general combining ability），并筛选出可在两种氮水平下均实现高产的优良自交系。研究采用顶交法（top-cross method）对55份部分自交S1后代系进行测评，将这些自交系与2个测验种（tester）杂交，得到110份顶交组合。2012年，在巴西中西部地区的2个试验点，于非主栽季对该110份顶交组合的籽粒产量（grain yield）进行了性状鉴定。本研究以各顶交组合单独分析所得的校正均值为基础，开展部分双列杂交分析（partial diallel analysis）；针对两个试验点，分别估算了部分自交系、测验种的配合力及其与氮素水平的互作效应。针对两种氮素水平分别选取一般配合力最高的15份部分自交系，其选择一致性系数为0.60。在两种氮素水平下均被筛选出的S1系包括39、11、41、55、38、37、6、8和14号，这表明这些自交系可用于筛选适配巴西中西部非主栽季种植的理想杂交品种。