Photosynthetic efficiency and chlorophyll fluorescence responses of Viola ignobilis Rupr. subjected to different biostimulants and two light intensities

Purpose: Viola ignobilis Rupr. is one of the important medicinal species which is in danger of extinction due to the over harvesting from the main habitats. Nowadays, domestication of medicinal plants in accordance with sustainable agricultural methods is a new important challenge. In this research, we used biostimulants and optimization of light intensity as eco-friendly approaches to improve yield and photosynthetic efficiency of V. ignobilis Rupr. Research Method: The experiment was set up in a split plot arranged in a randomized complete block design with 3 replications. The main factor was two light levels (50% and 100% of full sunlight) and as sub factors plants were treated with animal derived protein hydrolysate (A.PH), vegetal derived protein hydrolysate (V.PH), seaweed extract (SE), the combination of A.PH + SE and V.PH + SE and also, water served as a control. Findings: Light intensities and biostimulant application significantly impacted the morphological parameters including fresh and dry weight of roots and shoots compared to control plants. Furthermore, the photosynthetic pigments did not differ significantly in two light intensities, but, biostimulant application considerably increased the photosynthetic pigments concentration. The obtained results indicated that the highest value of assimilation rate, transpiration rate and stomatal conductance, and also chlorophyll fluorescence parameters including the highest values of qP, Fv/Fm and (ФPSII) were connected to plants treated with A.PH + SE biostimulants under full irradiance. Research limitations: No limitations were found. Originality/Value: Optimizing light condition and combined use of PHs + SE biostimulants due to synergistic effects can improve crop yield and photosynthetic efficiency in violet, when no other sources of fertilizers are available.