Effect of some plant growth promoting rhizobacteria and chemical fertilizer on growth parameters, yield and essential oil of fennel (Foeniculum vulgare Mill)

摘要

The use of renewable resources and inputs is one of the fundamental principles of sustainable agriculture that enables maximum crop productivity and minimal environmental risk. Therefore, in order to investigate the influence of bio- and chemical fertilizers on the growth parameters and the essential oil of fennel (Foeniculum vulgare Mill), an experiment based on a randomized complete blocks design with five treatments and three replications was carried out at the Agricultural Research Station, Shirvan Faculty of Agriculture, The Ferdowsi University of Mashhad, north east of Iran. The various treatments were the integrated application of Nitroxin biological fertilizer (contents Azospirillum sp., Azotobacter sp. and Pseudomonas fluorescens) and chemical fertilizer. Five treatments including 100% recommended dosage of nitrogen and phosphorous chemical fertilizers (NP) as a control (T-1), 50% recommended NP (T-2), Nitroxin + 50% NP (T-3), Nitroxin + 25% NP (T-4) and only Nitroxin (T-5) were used. The results showed that the application of a combination of bio- and chemical fertilizers improved the growth traits (plant height, number of umbels per plant, plant dry weight) of the fennel plants compared to the chemical fertilizer treatments only. Plants treated with Nitroxin + 50% NP (T-3) had significantly the highest plant height (76.5 cm), number of umbels per plant (48.5), dry weight (40.2 g) and fruit yield per plant (8.1 g). The application of a combination of bio- and chemical fertilizers also increased the amount of nitrogen, phosphorous and potassium in the plant tissues so that plants treated with Nitroxin + 50% NP (T-3) had the highest amount of nitrogen (16.1 mg g(-1) dry weight), phosphorous (10.2 mg g(-1) dry weight) and potassium (12.1 mg g(-1) dry weight) in the leaves, while the least amount of nitrogen (7.8 mg g(-1) dry weight), phosphorous (4.9 mg g(-1) dry weight) and potassium (6.1 mg g(-1) dry weight) occurred in the leaves of plants treated with 50% NP (T-2). The highest essential oil yield was also observed when using a combination of Nitroxin + 50% NP (T-3). However, the least amount of essential oil yield was obtained in plants treated with 50% NP (T-2). This experiment revealed that the replacement of up to 75% of the chemical fertilizer by the addition of Nitroxin bio-fertilizer would not reduce fennel yield and can therefore have an important role in sustainable resource management. The results also indicated that non-chemical sources of crop nutrition provide a reliable alternative to chemical fertilization in organic crop production in the agro-ecosystems of Iran.