Genetic variation in garden cress (Lepidium sativum L.) germplasm as assessed by some morphological traits

The morphological variation of 81 garden cress including 77 accessions of Genebank Department of Leibniz Institute of Plant Genetics and Crop Plant Research in Gatersleben, Germany and four ancient varieties collected from different geographical and bioclimatic areas of Iran were assessed based on 19 morphological traits. The genotypes were grown according to simple lattice design with four replications across 2 years (2012 and 2013). Significant differences among accessions were revealed for the majority of traits. The coefficient of variation varied from 18.05 (number of seeds per silique of lateral branches) to 52.79 % (biological yield) in the first year and varied from 9.12 (number of seeds of silique per plant) to 36.05 % (biological yield) in the second year. The first four factors explained 83.92 % of the total variation at year 2012 while the first four factors explained 76.93 % of the total variation at year 2013 among 81 of garden cress accessions. At both years, days to flowering, days to maturing, height of first branch and height of first silique, number of silique per lateral branches and number of siliques per plant were the most important traits contributing to the first two factors. This indicates that breeding programs should be based on these traits for improvement of garden cress. The regions of origin of the accessions were dispersed in ten sub-units which the first factor axis was much more important than the second one in separating the regions of origin of the accessions and separated sub-units five from four other sub-units, but this factor axis could not separate accessions of sub-unit I. Based on the observed structures of variation, it is concluded that the magnitude of morphological variation in the material studied is high and the implications of the results for plant breeding programs are discussed. The results of the present study can be used for breeding and improvement of garden cress for various desired traits through hybridization in future.