| Abstrakt: |
Background and Objectives: During the last decades, excessive application of chemicals in conventional agriculture has contaminated the environment due to contaminants, and harmful residues. Hence, sustainable agricultural practices such as nature-based solutions can be helpful to increase production and alleviate harmful effects on the ecosystem. Also, optimization of environmental conditions influences the physiological process and metabolism in plants and induces better growth and enhance crop yield. The experiments were conducted in a research field in Iran (Roudsar in Gulian province) to investigate the photosynthetic parameters, yield components, and mucilage content of Viola ignobilis Rupr. during 2021-2022. Materials and Methods: The study was set up in a split plot arranged in a randomized complete block design with 3 replications. In this work, two light regimes consisting of 50 and 100% full natural irradiance as the main factor and the biostimulant application including vegetal-protein hydrolysate (V-PH), animal-protein hydrolysate (V-PH), seaweed extract (SE), and the combination of V-PH + SE and A-PH + SE as sub-factors and untreated plants (control) were assessed. A foliar spray of the abovequoted protein hydrolysate was used on the leaves at (0.2 g L-1, 0) and the seaweed extract was applied directly to the soil (2 g L-1, 0). Results: The obtained results indicated that the fresh and dry weight increased at 100% light intensity by 11.66% and 29.39% respectively compared with shade condition. Also, the soluble carbohydrate and total protein showed higher amount in 100% light intensity by 14.18% and 19.29% respectively compared with shaded plants. The mucilage contents of leaf and flower was higher in 100% light intensity by 12.77% and 25.85% respectively. In this work, the root fresh and dry weight did not influence by the light intensity. The results showed that the highest fresh and dry weight of aerial parts, the number of flowers, total soluble carbohydrates, total protein, and mucilage contents of leaves and flowers obtained in plants were grown in full sunlight, whereas, the highest leaf area was recorded in 50% light intensity. Moreover, all kinds of biostimulant applications had positive significant impact on investigated traits. The highest means of yield components were related to A-PH + SE, but in many cases didn’t show any significant differences with V-PH + SE. In terms of mucilage content, the highest concentration of leaf and flower mucilage were connected to V-PH + SE, nevertheless, didn’t reveal any significant differences with other bio-stimulant, except the SE. The interaction between light intensity and bio-stimulants just impacted on the leaf area and the number of flowers. The light intensity did not show any significant effect on total chlorophyll and carotenoids, but, the biostimulant application increased considerably these photosynthetic pigments compared to the control. Moreover, the investigation of photosynthetic traits showed that transpiration rate, stomatal conductance and assimilation rate increased in full irradiance by 13%, 16.95% and 10.95% respectively in comparison with shade condition, Also, the biostimulant application highly increased photosynthetic traits compared with untreated plants. Conclusion: Overall, the results of this work exhibited that the optimizination and changes in the growth conditions of medicinal plants can be improved growth parameters and increased primary and secondary metabolites. The bio-stimulants application was caused to promote the growth parameters, photosynthetic efficiency, and mucilage production in violet. However, applications of seaweed extract in addition to protein hydrolysate had synergistic effects on all assessed growth parameters. [ABSTRACT FROM AUTHOR] |
