Effect of fertilizer sources on physiological and biochemical traits of rosemary (Rosmarinusofficinalis L.) in competition with weeds

Plant nutrition is an important factor in the growth and chemical composition of plants. The application of natural fertilizers can enhance the performance and pharmacological properties of plants. Rosemary (Rosmarinus officinalis L.) belonged to Lamiaceae family. Its essential oil is antimicrobial agent and also, its chemical composition, antioxidant properties and antimicrobial effects have been proven in various studies (40). Application of chemical fertilizers causes environmental pollution and ecological damage. One of the solutions to these problems is the use of sustainable agriculture principles in indigenous agricultural systems, including the use of organic fertilizers such as vermicompost and nanofertilizer. Considering the mentioned issues and taking into account the importance of rosemary herb, this experiment was conducted with the aim of investigating the effect of fertilizer sources on the physiological and biochemical characteristics of rosemary in competition with weeds conditions. This experiment was conducted as a split plot in a randomized complete block design in three replications in Sari Agricultural Sciences and Natural Resources University in 2016. The treatments consisted of: competition between plants and weeds (weedy and weed free) as a main factor, and sub factor was fertilizer sources include sheep manure, vermicompost, sheep manure +vermicompost, NPK fertilizer, NPK nanofertilizer and control (no fertilizer). The studied traits included: photosynthetic pigments (chlorophyll a, b, total and carotenoid), biochemical traits (total phenol, total flavonoids and antioxidant activity), nutrient content (NPK) and plant biomass. The results showed that the experimental treatments had a significant effect on the traits. highest levels of chlorophyll a (7.24 μg ml-1), chlorophyll b (2.66 μg ml-1), total chlorophyll (5.32 μg ml-1) and carotenoid (2.19 μg ml-1) was observed in vermicompost treatment, which was happen in weed free condition too. Maximum amount of total phenol (70.85 mg g-1 dry weight leaf), total flavonoid (46.43 μg ml-1 dry weight leaf) and antioxidant activity (91%) were observed in sheep manure with weed interference, sheep manure with weed interference and vermicompost without weeding, respectively. While, Maximum amounts of nitrogen (1.65%), and potassium (1.90%) were seen in vermicompost in weed free condition and for phosphorus (1.26%) in sheep manure with weed free, respectively. In general, the use of organic fertilizers, addition to positive environmental effects, has a positive effect on increasing the physiological and biochemical traits of the plant, which can be advantages economically and, on the other hand, improving the characteristics of the soil, leads to sustainable agriculture. Therefore, it seems that application of organic fertilizers can be effective in increasing yield and improving the quality of rosemary qualities.