German chamomile is an important medical plant with a long history of usage and a wide range of medical applications. Wild forms are diploid, whereas cultivated ones are diploid and tetraploid. Ploidy level variation within 15 origins (varieties, accessions, populations) of chamomile was investigated. Both naturally occurring triploids and those induced through directed crosses between diploid and tetraploid parents were identified and analysed, and these data could facilitate the exploitation of triploidy in chamomile as in other crop plants (fruit and ornamental plants).

Caraway (Carum carvi) is an economically important spice and medicinal plant of the Apiaceae family (syn. Umbelliferrae). Farmers often favor annual cultivation of caraway. However, the annual varieties, which are currently available, do not provide satisfying seed yields. Employing heterosis can be a promising approach to increase yield. Breeding of synthetic varieties utilizes heterosis and may be the method of choice for future caraway breeding. Knowledge of the outcrossing rate is important to evaluate the effectiveness of this breeding method. However, the outcrossing rate of caraway is unknown so far. We estimated the outcrossing rate of seven inbred lines under field conditions in a neighbor-balanced polycross design. For this purpose, we implemented a high-throughput genotyping system (PACE), accompanied by a high-throughput method for DNA extraction adapted to caraway. In total, more than 1300 individual plants were genotyped. We found a high variability of lines regarding outcrossing rate and other traits associated with flowering. The outcrossing rate was on average 66.5% and ranged from 51.6 to 82%. We discussed implications of our findings on the targeted breeding method.

The effect of genotype by environment interaction (G × E) was studied in marjoram in an experiment using 34 genotypes and three locations. For yield, no significant G × E was found, while for plant height, flowering time and the essential oil content, the G × E was significant. As to leaf colour, which was determined using the L*a*b* system and a sensorial score, only the coordinate a* was not significant. Both sensorial evaluations for smell and taste revealed some genotypes to be more stable than others. Regarding the essential oil compounds, both of the 'marjoramy' compounds, cis-sabinene hydrate and cis-sabinene hydrate acetate, were extremely unstable in one hybrid combination which, however, turned out to be the most stable comparing to the total amount of these two compounds. The main sesquiterpenes, β-caryophyllene and bicyclogermacrene, were strongly correlated in their stability, except in one case, where only bicyclogermacrene was highly unstable. The estimation of G × E allows the extrapolation of the degree of instability that is to be expected for a special trait. But, above all, when G × E is given special consideration, it is possible to select for stable genotypes that can be cultivated, e.g. in different regions with the resulting raw material being of higher homogeneity and the environmental influences minimised.

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