عنوان مقاله [English]
Drought stress is one of the abiotic factors that restricts crop growth and performance in most regions of the world. It causes changes in the growth of medicinal plants regarding the quantity and quality of their active ingredients. Fennel belongs to Apiaceae family that is growing in most parts of Iran. Essential oil that obtained from its seeds used in various industries of pharmaceutical, food, and cosmetics. Wide germplasm resources, genetic diversity among species, low water requirement and drought resistance have been factors for increasing importance of this plant. Despite of tendency to use and produce natural products, and importance of medical application of fennel, few studies have been existed and resulted in using local mass for cultivation in Iran. Studies suggested that for yield improvement, selection should be emphasis on plant height, primary branches, total plant branches and the number of effective umbrella in plant. The purpose of this research is to evaluated the morpho-phenological and quantities characteristics of different ecotypes of fennel and selection criteria for resistance and compatibility under water stress.
Materials and Methods
This experiment was conducted in a randomized complete block design with three replications at two locations of normal and end-of-season drought stress at the agricultural research farm of University of Birjand during 2014-2015 growing season. Ecotypes contained: Birjand, Mashhad, Nishabur, Gonabad, Bojnoord, Ilam and a Roman cultivar. Drought stress was treated before flowering by evaporation pan (Type A). Traits such as number of days to 50% flowering, days to 50% maturity, plant height, height of the main umbrella, the number of main branches per plants, the number of umbrellas, effective number of umbrella per plants, the number of seeds per main umbrella, the number of umbelets in main umbrella, Internodal length, internodes number and grain yield were measured. Analysis of variance and drawing By-Plot was carried out with GenStat 12 software. Cluster analysis and Pearson correlation coefficient analysis was performed using SPSS software.
Results and Discussion
Analysis of variance showed that the genotypes were significantly different for all traits except for the number of branches and the number of umbrella per plants in 1% probability levels. This result indicates that there is genetic variation in these genotypes for evaluated traits in normal and drought conditions. Correlation coefficient analysis showed a significant correlation between investigated traits under both normal and stress conditions. Result of cluster analysis was similar under both normal and stress condition and investigated ecotypes of fennel were divided to two distinct groups. Under normal condition, the highest seed yield was related to Birjand ecotype. Under drought stress condition, however, the highest seed yield corresponded to Mashhad, Nishabour, Khousf and Bojnord ecotypes while Romi and Ilam ecotypes where located in middle class for seed yield trait and lowest seed yield was related to Gonabad ecotype. Based on bi-plot analysis of genotype×traits, under normal conditions ecotypes such as Ilam, Gonabad and Khoosf had the highest value in plant height, internode length, days to maturity and the main branches. Under stress conditions, ecotypes such as Bojnoord, Mashhad, Nishabur and Roman had the best grain yield. Ilam and Khoosf showed moderate yield.
There was a significant difference between yields of different genotype under both normal and stress conditions that is related to the number of fertilized umbels and the number of umbels per plant. Under drought stress conditions genotypes such as Mashhad, Nishabur, Khosf and Bojnoord had the highest performance and belong in one class, while Ilam and Roman genotypes were in middle classes and Gonabad genotype stay on in lowest yield. The number of umbels per plant, the number of seeds per plant and umbels can be as effective traits on grain yield and can be the best criteria for selection in breeding programs.