The effect of organic and chemical fertilizers on growth, yield and essential oil of hyssop )Hyssopus officinalis L.(

Organic fertilizers are considerd as valuable sources for plant nutritions in agricultural ecosystems, because in addition to providing nutrients, they can also help to increase soil organic matter levels, which can compensate the deficiency of soil organic matter of arid and semi-arid regions. On the other hand, the use of organic fertilizers in the medicinal plants cropping has a higher priority due to the limited cultivation area of these plants and also the reduction of reliance on chemical fertilizers. Therefore, in this experiment, the effects of organic and inorganic fertilizers were investigated on growth, yield and essential oil of Hyssopus officinalis L.

The experiment was conducted as a randomized complete block design with three replications at the model cultivation site of medicinal plants of Koohrang Agriculture-Jahad (average rainfall of 1357 mm and minimum and maximum temperatures of 2.8 and 16.2 Celsius), in 2018 and 2019. The experimental treatments were 33 plots and includeed poultry manure with three levels of nitrogen uptake efficiency (100, 70 and 40%; PM100, PM70, PM40, respectively), sheep manure with three levels of nitrogen uptake efficiency (100, 70 and 40% SM100, SM70, SM40, respectively), cattle manure with three levels of nitrogen uptake efficiency (100, 70 and 40%; CM100, CM70, CM40, respectively), as well as two levels of control treatment (positive and negative; chemical fertilizer:100 kg N/ha + 100 P/ha and without fertilizer, respectively.The traits that assessed were included photosynthetic pigments, leaf area index, arial biomass, essential oil content and essential oil yield. Data analysis was performed by SAS software and means were compared by (least significant differences) LSD test.

In the first cutting (June 24), the results showed that the maximum contents of chlorophyll a and b were observed under PM40 and CF feeding conditions, respectively. PM40, PM70, PM100 and CF treatments had the maximum arial biomass (3760, 3672, 3632 and 3576 kg/ha, respectively) and were placed in a statistical group without significant. The highest essential oil content was obtained in PM40, CF and PM70 % treatments, with average of 1.49%, 1.33% and 1.3, respectively. However, the highest essential oil yield was observed in PM40, PM70, CF and PM100 fertilizer treatments (56.3, 47.8, 47.3 and 43.8 kg/ha, respectively). In the second cutting (September 5), PM40, CF, CM40 and SM40 treatments had the highest chlorophyll a (7.6, 7.2, 7.1 and 6.9 μg/ml, respectively), and CF, PM40 and PM70 had the highest chlorophyll b (6.8, 6.7 and 6.5 μg/ml, respectively). The maximum arial biomass was observed in conditions of feeding with PM40 and PM70, with average of 2801 and 2746 kg/ha, respectively. The amount of essential oil obtained from feeded plants was not significantly differed from control treatment. However, PM40 and PM70 treatments had the maximum essential oil yield with average of 50.7 and 43.6 kg/ha, respectively.

In this study, considering the maximum production of plant biomass in different levels of poultry manure and also the superiority of essential oil yield of these levels during the first cutting and PM40 and PM70 in the second cutting, it can be concluded that an average level of poultry manure is appropriate for hyssop regarding to its growth and essential oil production. Therefore, poultry manure can be used as an alternative source of chemical fertilizer in order to hyssop production in a similar climatic conditions to Koohrang.