Reciprocal difference of interspecific hybridization between three different colours of Iris dichotoma and I. domestica

Previously, we found that reciprocal F1 hybrids of purple-flowered Iris dichotoma and I. domestica were different. To further characterize this reciprocal difference, we carried out reciprocal crosses between three different colours of I. dichotoma and I. domestica. Morphological and cytological characters of F1 hybrids of six interspecific crosses between three different colours of I. dichotoma and I. domestica (three direct and their three reciprocals) were evaluated. The results showed that the fruit-setting rates of three different colours of I. dichotoma as female and I. domestica as male were lower than reciprocal cross combinations, but their seed germination rates were significantly higher than reciprocal ones. Reciprocal differences of F1 hybrids were observed for most morphological characters. The F1 hybrids of three different colours of I. dichotoma as female were totally different from their parents; however, the F1 hybrids of I. domestica as female were extremely similar to the mother. The six interspecific hybrids had the same chromosome number (2n = 32) as their parents. Reciprocal differences were detected for karyotype. Parents' and F1 hybrids' karyotypes focused on 1A to 2B. In these cases, the direction of the cross must be kept in mind in order to improve the efficacy of future breeding programmes.