Study of Phenological, Morphological and Phytochemical Characteristics of Ajwain (Trachyspermum ammi L.) Genotypes

Trachyspermum ammi (L.) Sprague or commonly Ajwain is an herbaceous herb belonging to the family Apiaceae and vastly grows in Egypt, Iran, Pakistan, Afghanistan, and India as well as European regions. Known as Zenyan or Nankhah in medical and pharmaceutical manuscript of medieval Persia, seeds of Ajwain were highly used by traditional healers for different ailments. Due to its various chemical constituents, the herb seeds were also evaluated for its numerous pharmacological properties. Moreover, numbers of chemical constituents have been reported for the herb. In addition, fiber (11.9%), carbohydrates (24.6%), tannins, glycosides, moisture (8.9%), protein (17.1%), fat (21.1%), saponins, flavones and other components (7.1%) involving calcium, phosphorous, iron, cobalt, copper, iodine, manganese, thiamine, riboflavin and nicotinic acid are of reported phytochemical constituents of Ajwain. Other studies showed that there was a difference among investigated ecotypes of Ajwain for following characters including plant height, number of branches, number of umbels, number of umbellets in an inflorescence, biological yield, single plant yield, and for number of secondary branches and oil content at 5% probability level. According to high correlation analysis between grain and oil yields, breeding for these two traits can be consistent in Iranian ecotypes of Ajwain. Oil contents percentage in ecotypes from south and center were more than other parts of Iran.

This study was carried out at Research Station of the Agricultural Research and Education Center of Khorasan Razavi, Iran during 2012-2013 crop years. In this experiment, 27 genotypes of Ajwain from different parts of the country were collected by the Natural Resources Genes Bank of Iran. Gene banks is a source for the right seed and look into several issues in order to improve levels of germplasm distribution and its utilization, duplication of plant identity, and access to database, for pre-breeding activities. In order to evaluate the morphological and phenological traits and to measure essential oil percentage, yield and yield components of Trachyspermum ammi for achieving superior germplasm. It was conducted in a randomized complete block design with three replications. Seed samples were first cultivated in the greenhouse and then transferred to the field and cultivated in drip irrigation conditions. Both fresh and dry weights were collected and measured for each sample. Seed size, yield components, biomass and grain yield as well as essential oil percentage were measured in all the cultured germplasm. All phenological stages including stem elongation time, flowering time and seeding time were counted and recorded during the growth period.

In this research, analysis of variance showed that there is a significant difference at 5% probability level between genotypes for a number of traits in different groups for 50% flowering time in 1.5 months, plant biomass 72-245 g.plant-1, seed yield 38-61.3 g.plant-1, and essential oil 3.08-11.22%. The highest positive direct effect (39%) on the yield of Ajwain essential oil was observed on biomass trait which has a positive and high correlation (53%) with the number of days to maturity. Different accessions of Ajwain have a potentially important source of genetic variation for the improvement of the cultivated species.  Genetic and environmental conditions play a significant and interrelated role on the emergence of traits. The selection of these traits is influenced by genotype and phenotype. High levels of genetic advance represent an incremental gene activity, while low levels represent the non-additive activity of the gene. The knowledge of genetic variability in a given crop species for characters under improvement is important in any plant breeding program. Understanding the nature and magnitude of variability among Ajwain genotypes for traits of economic importance is the goal of this study and it is vital to plan effective breeding programs.

As plant biomass has the highest positive direct effect on the yield of ajwain essential oil and a high correlation (53%) with the number of days to maturity, the selection of these traits should be considered with greater attention and emphasis on breeding programs. They were determined as suitable criteria and characters in plant breeding to produce the best of ajwain genotypes.