Growing, flowering and seeding characteristics of two forest violas (Viola caspia and Viola sintenisii) Compared to Viola tricolor under controlled conditions

Forests, along with their great advantages in environmental sustainability, are suitable and exclusive habitats for important plant species, including violets. Viola is an important forest plant in terms of recognizing flowering systems diversities, ornamental and medicinal importance. Medicinal violets are generally wild and natural. Cultivation and industrialization of drug production process from these medicinal plants, it is necessary to review and re-research them in controlled conditions. In this study, morphological differences, plant growth and developmental behavior especially flower buds production were studied in three different species of Viola: Viola caspia, Viola sintenisii and Viola tricolor (under greenhouse and field conditions). All greenhouse and field experiments were performed in a completely randomized design (CRD) and randomized complete block design (RCBD) with three replications, respectively. The species with a purple flowers (V. sintenisii) blooms about fifteen days earlier than a white flower violet (V. caspia) in spring season. Compared to these two species, the tricolor species blossoms two months earlier. Appearance and morphological tolerance to winter cold was the highest in V. tricolor and then in V. sintenisii was second.  The V. caspia tolerance to winter cold was lowest. Flower buds in the blue species (V. sintenisii) are formed in the first node located on the meristem and form a flower shoot up to a height of 11 cm. In white flowers (V. caspia) and ornamental violet (V. tricolor), unlike the first species, flower buds form on higher internodes, which are about 5 cm higher than the original node. The color of the underground stem in V. sintenisii and V. caspia was white and brown respectively. The type of flower produced in V. sintenisii and V. tricolor were chasmogam at all blooming time, but in the V. caspia it is of the type of cleistogam, semi-chasmogam and chasmogam. The size and shape of the fruits formed on all three studied species are different, which is round in V. sintenisii and elliptical in V. caspia and V. tricolor. The V. sintenisii grow in a sleeping and rosette state and tend to hang in pots, however the V. caspia and V. tricolor are completely vertical and non - rosette. The amount of violet scent (olfactory test) was the highest in V. sintenisii and then second in V. caspia but ornamental violet (V. tricolor) had no odor. Because the most of medicinal spices of viola are wild, it is challenging for compare of their different species for morphological and physiological characteristics as well as produce a standardized product with a high content of specialized metabolites (SM).  To overcome this great challenge, this study focused on the evaluation of growing, flowering and seeding characteristics of 3 forest violas under controlled conditions. This information will be so important for their domestication, cultivation, mass propagation and plant breeding programs.