Identification of drought-tolerant corn genotypes by multivariate analysis1

ABSTRACT The identification of genotypes that are tolerant to water deficit is crucial for the maintenance of the agricultural production. This study aimed to evaluate the genotypic variation for drought tolerance among corn genotypes by means of multivariate analysis, as well as to identify hybrids with high grain yield under conditions of water deficit and full irrigation. For this purpose, an experiment was conducted in a randomized block design, with 36 corn hybrids, being 34 experimental elite and two commercial (controls) hybrids, under water deficit and full irrigation, during the reproductive stage, with four replications. The irrigation levels, added to the rainfall, totaled 691.6 mm under full irrigation and 490.8 mm under water deficit. The evaluation encompassed the leaf area index, leaf chlorophyll content, interval between male and female flowering, number of rows per ear, number of grains per ear, ear length, 100-grain weight, ear yield, ear index, total number of grains, number of ears per m2, grain yield at 13 % of moisture and water-use efficiency. The evaluated hybrids showed useful genetic diversity for drought tolerance. Four experimental elite hybrids (3G7395, 3G7415, 1G7034 and 3G7335) stood out under water deficit, showing a high grain yield performance, if compared to the average of the control hybrids.摘要 鉴定耐旱基因型对维持农业生产至关重要。本研究旨在通过多元分析(multivariate analysis)评估玉米基因型间的耐旱性遗传变异，并筛选出在水分亏缺与充分灌溉条件下均具有较高籽粒产量的杂交品种。为此，本研究采用随机区组设计(randomized block design)开展试验，供试材料为36个玉米杂交品种，其中34个为试验性优良品种，2个为商业化对照品种，试验在玉米生殖生长期设置水分亏缺与充分灌溉两个处理，共设置4次重复。结合降雨量计算，充分灌溉处理的总供水量为691.6 mm，水分亏缺处理为490.8 mm。本试验测定指标涵盖叶面积指数(leaf area index)、叶片叶绿素含量、雌雄开花间隔期、果穗行数、果穗粒数、果穗长度、百粒重(100-grain weight)、果穗产量、果穗指数、总粒数、每平方米果穗数、含水率13%时的籽粒产量以及水分利用效率(water-use efficiency)。供试玉米杂交品种间存在可用于耐旱性研究的有效遗传多样性。在水分亏缺条件下，4个试验性优良杂交品种（3G7395、3G7415、1G7034及3G7335）表现突出，其籽粒产量显著高于对照品种的平均水平。