Atieh Drayabeigi; Faezehossadat Abtahi; Hossein Salehi Arjmand
Abstract
IntroductionToday, one of the most important environmental stresses that become a great threat to agricultural activities around the world is soil salinity. The salinity issue is more ...
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IntroductionToday, one of the most important environmental stresses that become a great threat to agricultural activities around the world is soil salinity. The salinity issue is more in arid and semi-arid climate finding hardy plants should be a priority. Therefore, the purpose of this study was to investigate the effect of salinity stress on morphophysiological and biochemical traits of some accesions of ajwain (Trachyspermum copticum L.). Materials and MethodsIn this study, the effects of salinity stress on two levels (control and 100 mM NaCl) as the first factor and 10 accesions of ajwain (Shiraz, Isfahan, Hamedan, Zahedan, Tabriz, Mashhad 1, Mashhad 2, Yazd, Ahvaz, Arak) as the second factor as factorial and the basis of a completely randomized design (CRD) with three replications (n =3) were evaluated in the research greenhouse of Department of Medicinal Plants of Arak University in pot conditions in 2019. In each experimental unit, a few seeds were sown, after emergence; additional seedlings were thinned to prevent competition, so that in each pot, finally, four strongest and uniform seedlings were kept. Until the seedlings reached 8-10 leaves, salinity treatment was done by irrigation with 500 ml of 100 mM NaCl solution. Plants were sampled and harvested to study the morphophysiological and biochemical traites of T.copticum L. in the flowering stage. The obtained data were statistically tested by analysis of variance (GLM) using SAS software Version 9.1 (SAS Institute, Cary, NC, USA, 1990). Duncan’s new multi range test was applied for means comparison and significant differences among employed treatments at P <0.05 and 0.01 using SPSS software Version 16 (SPSS Inc, Chicago, USA). The parameters, including minimum, maximum, mean and standard deviation (SD) were calculated. In order to identify some of the main factors to reduce the number of effective traits in differentiating populations, principal component analysis (PCA) was used. In order to have a simple structure and better interpretation of the results of the analysis, the data was rotated by Varimax procedure. Also, the two- dimensional plot was generated using the first and second principal components (PC1and PC2) with PAST software. Results and DiscussionThe results showed that salinity caused a significant decrease in plant height, fresh weight of aerial parts, dry weight of aerial parts and relative water content, while salinity caused a significant increase in leakage of electrolytes, phenols, flavonoids and antioxidant activity. Salinity stress had no effect on the content of photosynthetic pigments including chlorophyll a, b, total, and carotenoids. The highest height and fresh weight were related to the populations of Hamedan and Mashhad 1, respectively. Also, the lowest mean value of height and fresh weight was related to Arak population. No significant difference was observed among the investigated populations in any of the physiological traits, and only significant difference was observed in the antioxidant capacity, the highest of which was related to the population of Arak and the lowest was related to the population of Mashhad 1. The interaction between population and salinity was not significant in any of the traits. Based on the results of principal component analysis (PCA), the highest value of standard deviation was related to the flavonoid and the lowest value of the standard deviation was related to the trait of total dry weight of aerial parts. ConclusionSalinity negatively affects the growth and physiological responses of the plants. The results also showed that ajwain is classified as a relatively salt tolerant species, although there are significant differences between its accesions.
