Effect of planting method on seed yield and essential oil content of fennel (Foeniculum vulgare Mill.) ecotypes

Medicinal plants are among the most valuable natural resources in Iran which can play an important role in people health, job creation, and non-oil exports if they are properly identified, improved, cultivated and used. The increasing use of medicinal plants at the global level makes the importance of cultivation and production of these plants clearer. Currently, many researches are being conducted in the fields of identification of effective substances, therapeutic properties, cultivation and domestication of medicinal plants. Fennel (Foeniculum vulgare Mill.) is one of the medicinal plants that have many uses in foods, pharmaceutical and health industries, and is used in traditional Iranian medicine for long time. Therefore, the cultivation and production of this medicinal plant is of great importance.

To investigate the effect of direct seeding and transplanting on the yield and yield components of 10 fennel ecotypes, factorial experiment completely randomized complete block design with three replications. The experiment was carried out in the research field of the faculty of agriculture of the University of Tabriz, located eight kilometers east of Tabriz, Iran. Eight native fennel ecotypes of Iran from the provinces of Isfahan (Tatmaj Kashan), Isfahan (Zeyare), Alborz (Karaj), Lorestan (Khorramabad), East Azerbaijan (Bonab), North Khorasan (Shirvan), Hamadan and Ardabil (Meshkin Shahr) and two different foreign ecotypes from Germany (Saxony-Anhalt and Thuringia) were cultivated by two methods, direct seeding and transplanting.Seedlings were produced in winter in controlled environment and were transplaned in the field at the six leaf satge. In direct seeding, the seeds were sown in the mid April 2019. Hand weeding was done several times during the growing period. After harvesting the plants, sampling was done from the mid August until the late November 2019. Plant height, biological yield, seed yield, 1000 seed weight, essential oil content per hundred grams of dry matter and harvest index were measured and calculated.

The results of analysis of variance showed that main effect of ecotype and planting method were significant on seed yield and essential oil contents. The interaction effect of planting method × ecotypes was significant for all traits except for seed yield and essential oil content. The average seed yield in direct planting method was higher than that of transplanting, however, the essential oil content in transplanting method was higher than in direct seeding. The highest seed yield was related to the ecotype from Shirvan and the highest essential oil was related to the ecotypes from Germany (Saxony-Anhalt). The observed genetic variation for seed yield, important agronomic traits and the essential oil content among studied fennel ecotypes makes it possible to use these ecotypes in fennel breeding programs to develop cultivars with high seed yield and essential oil content.

The results of this experiment showed that there was considerable variation for most of the studied traits. Since the heritability for most traits was high, it can be concluded that most of this variation is probably related to genetic factors. Therefore, the selection of these traits can be effective for the development of fennel cultivars with higher seed and biological yields and essential oil content. The significant correlation coefficients between traits facilitates the indirect selection for important agronomic traits. The results of the cluster analysis showed that the morphological and phenological traits, to some extent, separated the fennel ecotypes based on geographical and climatic regions. The genetic variation among the studied ecotypes makes it possible to use these ecotypes in fennel breeding programs to develop new cultivars with high seed yield and essential oil content.