Evaluation of Quantity and Quality Yield of Cumin (Cuminum cyminum L.) Ecotypes in Different Planting Date under Sabzevar Climatic Conditions

Cumin (Cuminum cyminum L.) is one of the most important domestic herbs in Iran and is one of the earliest spices used by humans. Due to its characteristics such as short growing season, low water requirement, non-interruption of growth season with other agricultural products as well as high economic justification for other crops and export, it has found a special place in arid and semi-arid areas, including Sabzevar. Growth, yield and characteristics of medicinal plants are influenced by environmental factors such as temperature and light that can be varied by different sowing dates. Planting date is one of the most important factors in crop performance improvement and percentage of essential oil of cumin, which is resulted in weather parameters changes during the growing season and then in the production. In addition, the use of the adapted ecotype to the environmental conditions of the area plays a major role in achieving a proper performance. A high proportion of the total variation in yield is related to the interaction of genotype in planting history, which can greatly complicated the choice for a broad adaptation to different sowing dates. This research was carried out with aim of investigating the changes in yield of cumin ecotypes in different planting dates and determining the optimum planting time for this plant under Sabzevar climatic conditions.

In order to investigate the effect of planting date on quantitative and qualitative characteristics of different cumin populations, field experiment was conducted as split plots in a randomized complete block design with three replications in Sabzevar, Iran during 2016-2017. The factors included sowing date at three levels: 30 January, 20 February and 10 March, as well as different cumin ecotype in four levels of Sabzevar, Birjand, Kerman and Biyarjomand, respectively, assigned to the main plots and sub plots, respectively. Plant height, Umbel per plant, Seed per umbels, 1000- Seed yield, Biological yield, Essential oil yield and Essential oil percentage were measured and calculated accordingly. The treatments were run as an analysis of variance (ANOVA) to determine if significant differences existed among treatments means. Multiple comparison tests were performed for significant effects using the Duncan,s test.

The results showed that the highest number of umbels per plant, plant height, 1000-seed weight, seed yield and biological yield, as well as percentage of essential oil were obtained in the sowing date of January 30, and the delay in planting reduced the qualitative and quantitative characteristics of cumin. Among the studied ecotypes, Sabzevar ecotype had the highest number of umbrellas per plant, plant height, biological yield and essential oil percentage, as well as the highest number of seeds per umbels, seed yield and essential oil in Sabzevar ecotype and at sowing date of 30 January. It turned out that Sabzevar ecotype seems to have shown significant superiority to other ecotypes with higher potential performance in the studied environment. In this research, linear relationship between essential oil percentage and yield, as well as seed yield and essential oil yield were observed with 96% and 93%, respectively.

The optimum cumin’s planting date in one region causes reduction of the effects of non-biotic stresses during the growing season. The results of this experiment showed that in winter crop cultivation, seed yield and essential oil significantly decreased by delayed planting from January to March. In addition, Sabzevar ecotype in the study area had higher production potential. As for sowing date, the highest seed yield and essential oil were obtained in the first and second month of sowing. It seems that planting of cumin in the January increases the production potential due to increasing growth period and absorption of photosynthetic active radiation, as well as more effective use of plants from environmental factors.