Study of genetic diversity and heterosis in new hybrids of Iris germanica

Iris, both an ornamental and a medicinal plant native to Iran, is of special economic importance in the floricultural industry. Three cultivars in Iris germanica with characteristically brown and blue (female parent) and yellow colors (paternal line) were selected for hybridization. A total of 15 progenies from three parents were evaluated in a randomized complete block design with three replications. The research was conducted at the National Institute of Ornamental Plants in Mahallat, Iran, from 2011 to 2014. Analysis of variance of traits showed that with the exception of the flower diameter, significant differences in traits were observed (p≤0.01). The clustering of quantitative traits was based on the Ward method, and genotypes and parents were divided into five groups. The principal component analysis indicated six factors which could explain 88.15% of the variation. The majority of the hybrids associated with traits of the parent heterosis indicated superiority. The results showed that from the 15 evaluated progenies, progenies of population number NIOP8 had the highest stem diameter. However, compared with the superior parent and parents with a negative heterosis, these progenies had an improved crown diameter, flower branch diameter and peduncle diameter compared to other populations' progenies. Based on the length and width of the inner tepal, and selected leaf characteristics significant heterosis was observed for the progenies of two populations (NIOP5 and NIOP8) in comparison with superior parent and other populations. The frequencies of color spectra were purple-violet, purple, white and pale blue. A range of flower colors was obtained after hybridization with progenies showing the following trend: purple-violet>purple-white>pale blue in terms of flower color.