Physical characterization of cumin (Cuminum cyminum L.) schizocarps of different origins cultivated in Morocco

An initial investigation on the physical traits of the cumin (Cuminum cyminum L.) schizocarps was examined in order to select the best genotypes of cumin grown in three regions of Morocco (Drâa-Tafilalet, Marrackech-Safi, and Oriental). This operation was conducted on 34 cumin accessions from six origins (local, India, Syria, Egypt, Turkey, and Saudi Arabia). To evaluate differences between the physical properties among accessions, length, width, thickness, and both the volumetric mass and the thousand-schizocarp mass were measured. Geometric properties (geometric mean diameter, sphericity index, specific mass and surface area) and gravitational parameters (bulk density, true density, and porosity) were calculated for each accession. Heritability (broad sense), phenotypic and genetic variabilities are also assessed. The average values of the evaluated parameters were found to be significantly different (p < 0.01) between accessions. The physical characteristics of schizocarps were significantly influenced by their origin, cultivated provinces and irrigation methods. Length, width, thickness and length of style range on average from 5.7 to 6.8 mm, 1.5 to 2.5 mm, 1.2 to 1.8 mm and 0.6 to 0.9 mm, respectively. Local and Egyptian accessions were the best-sized accessions. Regarding the weight, the Indian accession C11 registered the best volumetric mass 52.9 g, while the thousand-mass was found to be higher in the local accession from Zagora C19 with 7.3 g. The results showed that the phenotypic coefficient of variation (PCV) was higher than the genotypic coefficient of variation (GCV). The highest PCV and GCV were length of style (30.0%) and true density (24.4%), respectively. Volumetric mass had the highest value of heritability (99%). PCA analysis of seed origin showed clearly the ordination of cumin schizocarps into three groups. The big-sized schizocarps group is composed of local and Egyptian accessions, while the Saudi Arabia accession was individualized in a single group. Regarding the cultivated zone in Morocco, the ordination of schizocarps according to the province revealed four distinct groups. Finally, this study showed that irrigation mode may also affect the physical properties of cumin schizocarps.