Evaluation of the Salinity Stress Effect on Cumin ( Cuminum cyminum L.) Ecotypes in Kerman, Iran

Author AB designed the study, the protocol and interpreted the data. Author MS anchored the field study, gathered the initial data and performed preliminary data analysis. Authors while AB and MS managed the literature searches and produced the initial draft. Both authors read and approved the final manuscript. ABSTRACT Cumin ( Cuminum cyminum L.) is one of the most important Medicinal plants. Since many semi arid and arid areas of Iran are affected by salinity and accessing water resources has been decreased. Proper measures need to be taken for water efficiency and efficient use of salt area in agriculture. Resources can be used in an optimum way by changing the planting pattern and using proper of cumin under salt stress. This research was conducted to determine the highest rate yield and tolerance against salinity stress of different ecotypes of cumin. The experiment was executed in the triple lattice with three repetitions in Kerman, Iran. The results showed that salinity stress has significant deference on traits such as seed index, seed yield, dry weight and harvest index, while it has non-significant result on other yield components such as plant height, number of umbel per plant, number of seeds per umbel and number of seeds per plant. The studied ecotypes had a significant difference regarding all of the characteristics. Therefore, the ecotype of Sepidan from Pars province was identified as the most tolerating and the ecotype of Qaen from Southern-Original Khorasan province was identified as the most sensitive ecotype under salinity stress regarding seed yield.


INTRODUCTION
Cumin belonging to umbelliferea, is an annual plant and one of the most important and oldest spice seed that has been used by humans. Economic value of cumin is the numerous uses of the seeds as a drug and spicy for about a thousand years ago [1]. It is regarded as part of food cultures in West Asia, a predominant habitat of this plant. Therefore, trade and consumption of the crop is almost limited to natural areas that product it [2]. In recent years cumin has been attended by farmers due to the low water requirement, tolerance to salinity and short growing season and according to the great importance of this plant and its growing cultivation, determination of the appropriate amount for each environment can worthy help this affair [3]. Salinity stress is the accumulation of soluble salts in the plowing's depth or around plant's roots to the extent that damage the plant growth and the product or destroy the plant. Salinity stress is one of the most extensive damage that is in desert and semi-desert areas due to salt accumulation, wetlands and coastal areas due to sea progression as well as soils with poor drainage. Plants growth under salt stress may be decrease with changes in osmotic potential due to low water potential in the root environment or the effects of specific ions [4]. Gory et al. [5] have tried to irrigate cumin plants with water which has 0, 4, 12 and 16 dS/m salinity. In this experiment, the higher salinity above 8 dS/m causes significant decreasing in performance. Moreover, Zidan and Elewa [6] analyzed the salinity effects caused by sodium chloride at levels of zero, 40, 80, 120, 160, 200, 240 and 280 mM on cumin germination and seedling growth characteristics in cumin and founded that germination was reduced greatly in high levels of salinity. Salt stress with NaCl, 40 and 80 mM decreased shoot and root length. Treatment with200 mM showed the significant decreasing in the shoot, root and dry weight. Nabizadeh et al. [7] reported that salinity below 50 mmol has no any effect on vegetative characteristics of cumin. There are many semi arid and arid regions of Iran are affected by salinity and also since accessing water resources has been declined, proper measures should be taken for water efficiency and efficient use of salt region in agriculture. Resources can be used in an optimum way by changing the planting model and using proper herbs that can tolerate salinity stress. This study was executed to determine the most rate yield and endurance against salinity stress of different ecotypes of cumin.

MATERIALS AND METHODS
Forty nine cumin ecotypes which they are subpopulations belonged to nine populations from different provinces of Iran that has the biggest variation for cumin (Table 1) [1]. It was laid out in a simple lattice design with two replications in the Agricultural Research field in Kerman (30º18´N, 57º6´ E and 1754AMSL) in 2013-2014. After preparation of soil and planting seeds, the field was irrigated by salty water in treatments of salinity and ordinary water in the control treatment. The genotypes were planted in plots of 4 m long. There was 50 cm row spacing and the distance between plants was 5cm. All experimental plots were treated uniformly.

Irrigation in Normal and Saline Environment
The First irrigation before planting was heavy. The second irrigation was performed just after planting and style. Supplemental irrigation during the growing season was done after 8 days and the last irrigation was performed 2 weeks before harvest. It was irrigated by natural saline water with pH 7.6 and conductivity equal to 3.55 dS/m. Plants were harvested after removal of edge effect, for measuring the traits 20 plants were selected. Characterizations such as plant height, number of seeds per umbel, number of umbels per plant, seed weight, seed yield, dry weight and harvest index were recorded.

Statistical Analysis
All data were subjected to analysis of variance (ANOVA) using SAS statistical software version 9 (SAS Institute Inc., Cary, NC, USA) and means were compared using Duncan significant difference test (HSD) at alpha 0.05 and Excel software.

Plant Height
The results of variance analysis showed that the effect of the environment on plant height wasn't significant. But ecotype interaction with the environment on plant height was highly significant ( Table 1). The mean compression results of the ecotype plant height effect showed the maximum height 19.55 cm in Jat and the minimum height 10.95 cm in Feridan ecotypes. It could be due to application of salinity stress after full deployment of plant, Therefore, at this stage, plant almost was done. Its length growth and has not apical meristem growth and its length growth is just for the internodes [8]. The mean environment interaction with ecotype examined environment without stress, Sorkheh with 20.80 cm and Feridan ecotypes with 10.50 cm had the highest and lowest height respectively. In stress environment, ecotypes as Sarvestan and Sirjan had the heights with 22.80 cm and the lowest with 10.40 cm plant height (Table 3). Zidan and Elewa [6] reported below 80 mM of salinity plant height of cumin increased.

Umbel Per Plant
According to the analysis of variance, there was no significant effect of environment on umbels per plant. The ecotype and environment interaction effects were highly significant (  (Table 3). Gory et al. [5] reported that a salinity of less than 8 dS/m has no significant effect on the components. The number of umbel per plant explained just about 96% of yield variation [9]. So, the increasing number of umbels in stress environment compared to no stress environment in different ecotypes is due to genetic differences which showed different responses.

Number of Seed Per Umbel
According to Table (1), results indicated that the environment has no significant effect on seed per umbel. However, the interactions between tested ecotypes and environment with ecotype were significant difference. Mean Comparison of ecotypes on number of seed per umbel showed that Sadoq and Maraveh-Tapeh ecotypes with an average of 9.55 had the most and Estahban with an average of 5.50 had the least number of seed per umbel. Reduction of umbel per plant increases the contribution of each umbel from Photosynthesis materials and it will increase the number of seeds per umbel [10]. In Stresses environment, Sadoq and Zarand ecotypes with averages of 10.60 and 5.40 were the most and least seed per umbel, respectively (Table 3). Kafi and Keshmiri [11] reported with increasing salinity, number of seed per umbel reduces. Moreover, Gory et al. [6] showed that the salinity less than 8 dS/m had no significant effect on the number of seeds per umbel.

Number of Seed Per Plant
The results of variance analysis showed that there was no significant effect of the environment on number of seed per plant. But ecotype interaction with the environment on number of seed per plant was highly significant (  (Table 3). Gory et al. [5] reported that salinity less than 8 ds/m and also Armin et al. [12] the salinity less than 6 µmhos/m had any effect on cumin yield components. The cause of increase in the number of seeds from per plant ecotype in stress compared to without stress environment might be the genetic salt tolerant of ecotype.

Seed Weight Index
The results of seed weight index showed that the effect of the environment on this trait is very meaningful and stress had significant deference on seed weight index. Moreover, environment with ecotype interaction was a highly significant difference (Table 1). According to the results of the mean comparison for environment effect on seed weight index exhibited Natanz with mean 0.3885g and Baneh ecotypes with mean of 0.2605 g had the highest and the lowest seed weight. Results of mean Comparison indicated environment with ecotype interaction in nonstress environment with an average of 0.4200 g in Natanz is the maximum and Birjand ecotype with an average of 0.2550 g was minimum seed weight index. However, ecotypes of Qaen and Taybad with averages of 0.4110 and 0.2530 g were the highest and the lowest seed weight index in salinity environment, respectively ( Table  3). The Latest part of yield is seed weight index in cumin that influenced by genetic factors [13]. Kafi and Keshmiri [11] reported that, increasing salinity reduces seed weight index. But Armin et al. [13] stated that the salinity less than 6 µmhos/m has no effect on seed weight index.

Seed Yield
The results demonstrated seed yield per hectare that the effect of the environment on this trait has a high significant difference. Ecotype effect and environment with ecotype interaction also has a significant difference ( Table  2). Mean Comparison showed that Shahmirzad and Baneh ecotypes with averages of 1224kgha -1 and 470.50 kgha -1 , had the highest and lowest seed yield, respectively. The mean comparison environment with ecotype interaction explained stress reduces seed yield per hectare for all ecotypes in the two environments. Mean Comparison showed that the non-stress environment, ecotypes of Sivand and Bardeskan with an average of 1800 kgha -1 to 540 kg ha -1 were the highest and the lowest seed yield. In environment stress, Sepidan and Qaen ecotypes, with averages of 776kg ha -1 and 240 kg ha -1 included the highest and lowest seed yield, respectively ( Table 4). The effect of salinity can reduce plant growth and changes in photosynthetic products transported to the roots, decreasing shoot growth, especially leaves or the partial or total closure of stomata could be due to a direct effect of salt on the photosynthetic system or affect the ion balance [14]. Kafi and Keshmiri [11] showed that increasing salinity in cumin causes loss weight and reduced economic performance cumin seed in per hectare.

Dry Weight
The results illustrated the effect of the environment in ecotype and environment with ecotype interaction on this trait was highly significant ( Table 2). According to comparison mean of environment and ecotype effects on this trait can be concluded that Jat and Naien ecotypes with means of 2330.33kg ha -1 and 2316kg ha -1 have the highest dry weight, respectively and also Taybad with mean of 918 kg/ha had the lowest. Mean comparison about environment with ecotype interaction showed that non stress environment ecotypes such as Joopar (3412 kg ha -1 ) and Bardeskan (960 kg ha -1 ) were the highest and lowest dry weight, respectively. Moreover, in salty environmental Darmian ecotypes with an average of1732 kg ha -1 and Nehbandan with an average of 474 kg ha -1 had the maximum and minimum dry weight, respectively (Table 4). Zidan and Elewa [6] reported that increasing salinity reduces dry weight of cumin.

Harvest Index (H.I)
Analysis of variance indicated that H.I has been affected by stress. There was a highly significant difference between studied ecotypes and environment with ecotype interaction (  (Table 4). Since this index represents the ratio economic yield (seed yield) with biological yield (dry weight). However increasing seed yield compared to increasing dry weight were not uniformly, this trait has been increasing or decreasing. Kafi and Keshmiri [11] reported that seed weight decreases with increasing salinity. Zidan and Elewa [6] stated that increasing stress could be decreasing dry weight. While Gory et al. [5] reported that salinity less than 8 ds/m is ineffective on yield components.

CONCLUSION
Salt stress had a significant difference on traits such as seed weight, seed yield, dry matter and harvest index. But on the other yield components such as plant height has had no significant effect. These minor changes in yield components such as plant height due to the greater impact of salinity on vegetative parts of the plant which has led to reduced cell division and vegetative growth. Ecotypes responded effect on difference to salinity was studied. That represents for genetic diversity and tolerance to stress. Ecotypes of Sepidan and Maraveh-Tapeh belong to Fars and Golestan provinces had the highest seed yield and harvest index in environment with stress. Sivand and Ravar ecotypes belong to Fars and Kerman provinces had the highest seed yield and harvest index showed in environment without stress. At least Sepidan ecotype from Fars province and Qaen ecotype from Southern-Khorasan were the most tolerance and sensitive to salinity stress.