Evaluation of some Iranian watercress (Nasturtium officinale L.) populations using agro-morphological traits

Watercress (Nasturtium officinale L.) is a perennial member of the Brassicaceae family and naturally grows in abundance near springs and open-running waterways in Europe, America and Asia. The plant seeds are rich sources of glocunasturtiin which its hydrolysis product, 2-phenethyl isothiocyanate (PEITC), is believed to be cancer preventing. The present study was aimed to evaluate twenty-four wild growing populations of N. officinale collected from six provinces of Iran using agro-morphological traits. According to the results, plants of Noshahr population had the minimum number of silique per plant (8.71) and the lowest length of flowering stems (4.86 cm). The highest plant fresh weights were recorded in plants collected from Sarab (50.73 g) and Mehraban (40.94 g). The highest anthocyanin content was visually observed in plants of Uromieh 1 and Uromieh 2 populations. Three kinds of leaf shape were identified in studied populations. Correlation studies revealed significant relationships between some measured characteristics such as number of leaves with the leaf width and leaf length and leaf width with the plant height (correlation coefficients 0.825, 0.720, 0.880, respectively). Cluster analysis divided populations in question into four main groups including 13, 8, 2 and 1 members. Members of the first group had the lowest plant fresh weights and visually lacked anthocyanin. The similarity point of plants in the second group was based on the traits of leaf length, leaf width and the existence of anthocyanin. Plants of the third group were similar from the perspective of plant fresh weight and the plant height, and finally there was clear difference in the fourth group (including Noshahr population) from the perspective of silique and the leaf thickness. Considering morphological diversity observed in the present study, Iranian watercress populations have the potential to be used in the breeding programs of this plant.