Effects of organic and biological fertilizers on fruit yield and essential oil of sweet fennel (Foeniculum vulgare var. dulce)

R. Moradi,A. Nezhadali,P. Rezvani Moghaddam,M. Nasiri Mahallati

doi:10.5424/sjar/20110902-190-10

Abstract

In order to evaluate the effects of different organic and biological fertilizers on quantity and quality of fennel essentialoil, an experiment was conducted in a completely randomized block design with three replications. The experimentaltreatments included two organic (compost and vermicompost) and two biological (Pseudomonas putida and Azotobacterchroococcum) fertilizers, their all twin combinations (Ps. putida + A. chroococcum, Ps. putida + compost, Ps. putida + vermicompost, A. chroococcum + compost, A. chroococcum + vermicompost and compost + vermicompost) and control (non fertilized). There were significant differences between treatments in terms of seed essential oil percentage, essential oil yield; anethole, fenchone, limonene and stragole content in seed essential oil. Results showed that the highest and the lowest percentages of essential oil were obtained in control (2.9%) and A. chroococcum + vermicompost (2.2%) treatments, respectively. The highest essential oil yield (29.9 L ha–1) and anethole content of essential oil (69.7%) and the lowest contents of fenchone (6.14%), limonene (4.84%) and estragole (2.78%) in essential oil were obtained in compost + vermicompost treatment. It seems that compost + vermicompost treatment compared to other treatments supplied the highest equilibrium of nutrients and water in the root zone of sweet fennel which is led to increasing the anethole content, there upon, decreasing other compounds. Essential oil yield and percentage of anethole content in essential oil were significantly higher in all organic and biological treatments compared with control.

Highlights

Chemical fertilizers are key components for providing crop nutrients needs in recent years (SharifiAshori-Abadi, 1998)
The results showed that different treatments had no significant effect on essential oil percentage
While there were no significant differences between different treatments in terms of essential oil percentage but because of the higher fruit yield in vermicompost plus compost treatment, (Moradi et al, 2010) the essential oil yield was higher in this treatment compared with others

Summary

Introduction

Chemical fertilizers are key components for providing crop nutrients needs in recent years (SharifiAshori-Abadi, 1998). To avoid the risk of these negative effects of chemical fertilizers, it is necessary to use organic or biological fertilizers which provide plant nutrients and increase long term sustainability of agroecosystems (Murty and Ladha, 1988; Mehnaz and Lazarovits, 2006). Previous studies have shown that the PGPB can fix the atmospheric nitrogen, dissolve the phosphorus and potassium of the soil and control the pathogen via producing plant growth regulators (Sturz and Christie, 2003). These bacteria are known as «yield promoting bacteria» because they improve increasingly growth and development of plants (Sturz and Christie, 2003). Among the PGPBs, Azotobacter chroococcum and Pseudomonas putida are the greatest prevalent species, founding in the soil, that fix nitrogen and phosphorus, respectively (Kumar et al, 2001; Seilsepour et al, 2002; Vessey, 2003)

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Conclusion