Evaluation of biochemical and physiological traits of corn S6 lines under normal and water deficiency conditions and examining their kinship relationships by cluster analysis

In order to investigate the response of 15 maize S6 lines to drought stress, a split plot design based on randomized complete block design with three replications was conducted in 2015 year at the research field of Graduate University of Advanced Technology, Kerman, Iran. In this study, the main factor was stress at two levels (normal with five days irrigation and low irrigation with ten days irrigation) and the sub-factor was maize line at 15 levels. The results showed that there were significant differences between stress levels and lines for all studied traits (chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, soluble sugars, protein and proline content). Mean comparison of lines showed that lines 9, 3 and 5 had the highest proline content under drought stress conditions. The lowest phenotypic coefficient of variation was for total protein (2.59) and the highest for proline (74.17). Cluster analysis divided the studied lines into four, five and six groups in normal, drought and mean conditions, respectively, and the similarity of their grouping was high. Based on the results of cluster analysis and mean comparisons, lines with high genetic distance were grouped together. Thus, three groups, each with five lines, were found to be used in the planning of breeding projects and cross-breeding programs. Line 9 also showed a high mean for most of the studied traits in both conditions and it can be considered as a promising line in future experiments.