Fruit yields, essential and fixed oil content, essential oil component and fatty acids profile of fennel in response to different doses of sheep and cow manures

Abstract

Fennel ( Foeniculum vulgare L.) is a well-known aromatic plant belonging to the Apiaceae family, which is extensively cultivated worldwide as a culinary spice. Although organic cultivation of medicinal and aromatic plants can improve the quality and safety of medicinal plants, the appropriate dosage of organic fertilizers is critical to avoid agricultural and environmental problems. This research was carried out to assess the effects of various doses (7.5, 15, 22.5, and 30 t ha − 1 ) of cow (CM) and sheep manure (SM) applied on the morphology, yield, and desired quality characteristics of fennel during the 2019 and 2020 vegetation periods. The results showed that different application rates of SM and CM had significant effects on the yield and quality characteristics of fennel plants compared to the control. On the basis of the two-year mean values, application of the CM at 22.5 t ha − 1 (1.7 t ha − 1 ) and SM at 22.5 t ha − 1 (1.6 t ha − 1 ) produced the greatest fruit yield. The highest essential oil content was obtained from CM at 15 t ha − 1 (26.4 L ha − 1 ) and SM at 22.5 t ha − 1 (25.2 L ha − 1 ), while cow manure applied at 15 t ha − 1 (21.6%) and 22.5 t ha − 1 (19.1%) had the highest values of fixed oil content. Trans -anethole, limonene, anisaldehyde and camphor were the major constituents among all the applications. CM applied at 22.5 t ha − 1 (37.7%) and SM applied at 22.5 t ha − 1 (35.9%) recorded the highest values of trans -anethole content. So, SM and CM can help produce high-quality fennel fruit by decreasing the chemical fertilizer uses and minimizing environmental pollution.