Effect of Different Levels of Vermicompost and Copper Sulfate on Morphological Characteristics, Yield, and Yield Components of Basil (Ocimum basilicum L.)

Basil (Ocimum basilicum) is an herbaceous medicinal plant from the Lamiaceae family with a wide range of applications in the culinary, cosmetic, food, perfumery, and medical industries. The presence of more than 200 chemicals, including flavonoids, monoterpenes, sesquiterpenes, triterpenes, and aromatic compounds in basil oil, have been identified. The main components of its oil are eugenol, methyl eugenol, linalool, estragole, and anethole, varying by chemotype. Basil is one of the most important medicinal plants in Iran, which is widely used in various industries, including pharmaceuticals, cosmetics, sanitary, and food industries, and it is considered an anti-fluff and appetizer in traditional medicine. Therefore, to maximize yield and increase the length of the basil production period, the appropriate management of this product is necessary. Among these, the use of suitable nutritional elements is one of the useful ways to improve the performance of this plant. The centers of origin of basil are the tropical and subtropical regions of Africa, Asia, and South America. Therefore, the purpose of this study was to evaluate the effects of different levels of vermicompost and copper sulfate and their interaction on vegetative, reproductive growth, and yield of basil's medicinal plant.

To investigate the effect of vermicompost and copper sulfate on some vegetative and reproductive characteristics of the basil plant, an experiment was carried out as factorial based on a randomized completely block design with three replications in the research farm of Birjand University, Iran, during the growing season 2017-2018. Treatments were three levels of vermicompost (0, 5, and 10 t.ha-1) and three levels of copper sulfate (0, 3, and 6 per thousand) with three replications. The measured indices include vegetative characteristics (plant height, lateral number, plant fresh and dry weight, leaf fresh and dry weight, number of leaves and node per plant, lateral branch length internally spaced, and diameter stem) and reproductive characteristics (inflorescence number and length, number of plant seeds, the weight of one thousand seeds, harvest index, grain performance, and biological function).

The results showed that the studied treatments had a significant effect on the number of lateral branches, plant dry weight, number of leaves per plant, lateral branch length, number of seeds, 1000-seed weight, harvest index, grain yield, and biological yield so that the highest number of lateral branches (17.33), Plant dry weight (14.83 g.m-2), Number of leaves per plant (167), Lateral branch length (26.83 cm), Number of seeds (3854.3), 1000-seed weight (1.80 g), Seed yield (3350 kg.m-2) and biological yield (20968.3 kg.m-2) basil was obtained in the treatment of 5 t.h-1 of vermicompost and 6 per thousand of copper sulfate and its advantage over the control was 67, 51, 16, 43, 79, 26, 87 and 26%, respectively. Harvest index in the treatment of 5 t.h-1 of vermicompost and 3 per thousand of copper sulfate with 13.01 in its maximum amount.

In general, the results indicated a positive and incremental effect of the combined application of the chemical and organic fertilizers on the yield of the basil plant, and according to the results, treatment with 6 per thousand copper sulfate and five t.ha-1 vermicompost was recommended as the best treatment for increasing yield. But always in agricultural products, especially in the production of basil as a medicinal and vegetable plant, the best results in terms of crop production and health, as well as essential oils and medicinal compounds, were related to the combined treatments of organic and chemical fertilizers, because these treatments are relative compared to organic treatments alone, they increased the yield and on the other hand, compared to chemical fertilizers, they had a healthier product and more medicinal compounds.Acknowledgments: Authors are grateful to Ebrahim Ebrahimabadi for their help with the field experiments.