Breeding programs in ornamentals can be facilitated by integrating knowledge of phylogenetic relatedness of potential parents along with other genomic information. Using AFLP, genetic distances were determined for 59 Geranium genotypes, comprising 55 commercial cultivars of the three subgenera of a total collection of 61 Geranium genotypes. A subgroup of 45 genotypes, including intragroup and intergroup hybrids, were selected and further characterized for genome sizes and chromosome numbers. The variation in genome size ranged from 1.51 ± 0.01 pg/2C to 12.94 ± 0.07 pg/2C. The chromosome numbers ranged from 26 to 108–110 with some hybrids showing an aberrant number of chromosomes based on their parents’ constitution. All chromosome numbers of Geranium are an even number, which presumes that unreduced gametes occur in some cross combinations. Overall, parental difference in genome size and chromosome number were not limiting for cross compatibility. Good crossing compatibility was correlated to a Jaccard similarity coefficient as parameter for parental relatedness of about 0.5. Additionally, parent combinations with high differences in the DNA/chromosome value could not result in a successful cross. We expect that our results will enable breeding programs to overcome crossing barriers and support further breeding initiatives.

The current study examined the effect of chemical and organic fertilizers on yield components and essence content of peppermint (Mentha piperita L.). The experiment was carried out in randomized complete design with 7 treatments and 4 replications in Sari Agricultural Research Center, Iran, in 2013. Treatments were: 1-control, 2-sheep manure, 3-vermicompost, and basic chemical fertilizers at different contents as 4-N60,P50,K60 kg ha -1 which equals 0.24, 0.2 and 0.24 g per pot, respectively), 5-N60,P80,K60, 6-N90,P50,K80 and 7-N90,P80,K80. There were 28 pots that 10 kg soil was added to each of those and chemical fertilizer (at determined rates), sheep manure and vermicompost fertilizers (both at the content of 20 ton ha -1 equal 80 g per pot) were also added in per selected pot as treatment. The results showed that the effect of all treatments was very significant on the all agronomic properties and yield of peppermint. Some agronomic and quantitative traits of peppermint like plant height, number of chain, stem wet and dry weight, leaves wet weight and total wet and dry weight were obtained at the maximum values when basic chemical fertilizers was applied at the rate of 90-80-80. The maximum number of stems, number of flowers, number of suckers, leaves dry weight and essence content were also attained by sheep manure. Thus, to prevent soil, plant and finally environment pollution by using chemical fertilizers

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Key message. The success of interspecific hybridization in hardy geranium (Geranium sp.) can be predicted by considering the genetic distance between parental genotypes and using the logistic regression model developed in this study. Hardy geranium is a popular ornamental plant known for its architecture, hardiness, prolonged flowering, and diverse colors in leaves and flowers. In ornamental breeding, the pursuit of novel trait combinations is never-ending. Even in Geranium, certain combinations of valuable traits have not yet been achieved. Interspecific hybridization can increase diversity; however, success remains low due to pre- and postzygotic barriers. Crossing success can be predicted by response criteria such as pollen tube growth (tube_length), seed development (seed_dev), and seed setting (seed_set). Within a collection of 42 Geranium genotypes and during two consecutive breeding seasons (years), we evaluated tube_length, seed_dev, and seed_set for 150, 1155, and 349 crosses, respectively. These crosses varied in four parental differences (variables): chromosome number (Chrom), DNA/chromosome (DNA), style length (Style), and genetic distance expressed as the Jaccard distance (cJaccard = 1 − Jaccard). Using logistic regression models has confirmed that most often, the success rate decreased with increasing parental distance. The most consistent association was seen in seed_dev in combination with cJaccard. The model was used to predict the number of crosses necessary to have 10 successful crossing products by taking into account the uncertainty in the model. These findings provide valuable guidance for future planning of interspecific breeding experiments in Geranium. By incorporating the genetic distance between parental genotypes, breeders can enhance the efficiency and success of hybridization efforts.