Investigating the Effect of Cultivation Method and Pre-Soaking of Seed on Seed and Essential oil Yield of Cumin (Cuminum cyminum L.) Under Dry Farming

Document Type : Full Paper

Authors

• Rooholla Moradi ¹
• Amir Hossein Saeidnejad ²
• Seyyed Masoud Ziaei ³

¹ Department of Plant Productions, Agricultural Faculty of Bardsir, Shahid Bahonar University of Kerman, Iran

² Crop and Horticultural Science Research Department, Kerman Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Kerman, Iran

³ Department of Plant Productions, Higher Education Complex of Saravan, Saravan, Iran.

Abstract

Keywords

• Emergence percentage
• Essential oil percentage
• Germination
• Land leveling
• Tillage

Main Subjects

• Medicinal plant science

Extended Abstract

Introduction

Medicinal plants play major roles in human health services worldwide. Many people in both developing and developed countries are turning to herbal medicine. Iran has a long medical tradition and traditional learning of plant remedies. Besides serving medical and cultural functions, medicinal plants also have an important economic role across the country. The planting area of medicinal plants is about 166,527 ha, which contains nearly 1% of the total planting area in Iran. Cumin (Cuminum cyminum L.) is an annual plant, which commonly cultivated in arid and semiarid regions of Iran, especially in Great Khorasan province. India (70%), Syria (7%), Turkey (6%) and Iran (6%) are the main producers of cumin. The crop has a wide range of uses, including in the medicinal, cosmetic and food industries. Cumin occupies about 26% of total area devoted to medicinal plants in Iran.

In arid regions, cumin production is widely limited by poor stand establishment and nutrient deficiencies. Cumin seeds germination tends to be irregular and can extend over long periods, particularly in drought-prone environments. The adverse effects of drought stress can be alleviated by various measures, including seed priming (pre-sowing seed treatment). The general purpose of seed priming is to partially hydrate the seed to a point where germination processes are begun, but not completed. Treated seeds are usually re-dried to primary moisture before use, but they would exhibit rapid germination when re-imbibed under normal or stress conditions. Such controlled imbibition of seed followed by dehydration was shown to improve germination and early seedling growth under salt and drought stress, compared to seedlings grown from untreated seed. Various pre-hydration or priming treatments have been employed to increase the speed and synchrony of seed germination.

On the other hand, it should be noted that the cultivation method in dry farming can affect the yield of cumin. Different tillage and cultivation methods can affect the germination of seeds by changing the physical conditions of the seed bed, such as moisture, heat, ventilation and resistance characteristics of the soil. Plant establishment is generally considered as a criterion for evaluating the quality of the substrate and cultivation method. The number of emerged plants and their growth conditions are an indicator of the number of seeds that have successfully germinated and sprouted from the soil.

Materials and Methods

In order to investigate yield, yield components and essential oil quantity of cumin as affected by cultivation and pre-soaking methods, a split plot experiment was conducted based on randomized complete block design with three replications. The main-plot of the experiment was cultivation method in two levels (cultivation in a leveled and non- leveled method), and duration of seed pre-soaking in four levels (6, 12, 24 and 48 hours) was consisted as sub-plot.

Results and discussion

The highest and lowest number of emergent plants were observed in the 12 and 48-hours seed pre-soaking treatments, respectively. When the seeds were not soaked, the number of emerged plants in the leveled cultivation method (48 plants per m²) was more than that of non-leveled cultivation method (41 plants per m²). But, for the treatments of 6, 12 and 24-hours pre-soaking, there was an opposite trend. In both cultivation methods, the highest plant height and number of umbrellas per plant were obtained in the 48-hour seed pre-soaking treatment. In all seed soaking treatments, seed yield was significantly higher in non-leveled than leveled cultivation method. The highest seed yield (78. 64 g m^-2), biological yield (188. 7 g m^-2) and essential oil yield (1.82 ml m^-2) were obtained in the cultivation method without leveling with 12-hours of seed pre-soaking. In the leveled cultivation method, the non-presoaked seeds significantly produced the highest essential oil percentage (2. 14%), but in non-leveled cultivation method, the highest essential oil percentage (2. 60%) was observed in 48 hours of seed pre-soaking, which it had no significant difference with other seed pre-soaking treatments in terms of essential oil percentage. Among the investigated traits, essential oil yield had the strongest correlation (r=0.912) with the seed yield. In other words, seed yield was the most influential factor in producing cumin essential oil.

Conclusion

The results illustrated that the pre-soaking of cumin seeds can be important in rainfed cultivation and soaking the seeds for 12 hours had a notable effect on the plant emerging and seed yield. Another important point was that soaking cumin seeds for more than 12 hours does not have a positive effect. Also, the results confirmed that cultivation cumin seeds in uneven land (no-leveling after plowing) due to shading of the rhizosphere, reducing the evaporation, preventing runoff and maintaining more soil moisture led to improvement of cumin yield.