Document Type : Original Article

Authors

• Hydar Flayyih ¹
• Jafar Nabati ²
• Ahmad Nezami ³
• Mohammad Kafi ³
• Mohammad Javad Ahmadi ²

¹ Ph.D. Student Department of Agrotechnology, Faculty of Agriculture, Ferdowsi University of Mashhad, Iran

² Assistant Professor Department of Agrotechnology, Faculty of Agriculture, Ferdowsi University of Mashhad, Iran

³ Professor, Department of Agrotechnology, Faculty of Agriculture, Ferdowsi University of Mashhad, Iran

Abstract

Introduction
The growth of chickpea plants is severely affected by salt stress, leading to a significant reduction in their performance. Therefore, identifying salt-tolerant genotypes of chickpea can greatly help improve plant resilience and enhance productivity under stressful conditions.
Materials and methods
This research was conducted with the aim of studying the salt tolerance of Kabuli chickpea genotypes under field conditions in 2021-2022. Salt stress was applied at two levels: 6 and 9 dS.m^-1, along with a control level of 0.5 dS.m^-1. The genotypes were evaluated based on their response to these salt stress levels. The irrigation treatments were applied uniformly and complementarily in three stages for 12 genotypes: before flowering, during flowering, and pod filling. Sodium chloride was used to induce salt stress levels. The volume of irrigation water given to each plot was measured using a water counter, and the same amount of water was considered for all treatments.
Results and discussion
The investigation demonstrated changes in the levels of secondary metabolites and leaf chlorophyll content under salt stress conditions, depending on the plant genotype. In genotypes MCC52, MCC65, MCC77, and MCC92, salt stress reduced the content of plant pigments. The reduction in chlorophyll content in plants under the influence of salt stress is associated with an increase in the activity of chlorophyll-degrading enzymes, alterations in nitrogen metabolism, and the utilization of glutamate due to its involvement in the proline synthesis pathway. Increased scavenging activity of the free radical DPPH was observed in genotypes MCC12, MCC27, MCC28, MCC72, MCC92, and MCC108 under salt stress of 9 dS.m^-1. The activity of the enzyme catalase increased in most studied genotypes under 6 dS.m-1 salt stress, but decreased with the increase in stress level to 9 dS.m^-1. The highest activity of the enzyme ascorbate peroxidase was observed in genotype MCC29 under 6 dS.m^-1 salt stress. The decrease in the osmotic potential in plants is a consequence of cellular water conservation under stress conditions. This is because, under salt stress, the plant needs to maintain a more negative water potential in order to absorb water. Therefore, there is a greater need to increase the concentration of compatible osmolytes. Plants with higher antioxidant capacity demonstrate better resistance to oxidative stress due to their ability to detoxify free radicals. The application of salt stress at a level of 9 dS.m^-1 led to a significant increase in sodium content in all genotypes compared to the control treatment. In over 65% of the studied chickpea genotypes, applying 6 dS.m^-1 salt stress resulted in an increase in potassium content in the plant, while 9 dS.m^-1 salt stress reduced leaf potassium content. The reduction in potassium content in plants is due to the substitution of sodium in place of potassium and calcium. The competition between potassium and sodium ions for uptake sites in the roots is one of the factors that increases sodium content and decreases potassium content. Plant dry weight increased by 25% in genotype MCC72 and more than three times in genotype MCC108 under the highest level of stress compared to the control treatment. In genotype MCC108, the application of the highest level of stress also increased seed weight in the plant by approximately 73% compared to the control treatment. With the imposition of salt stress and the decrease in water potential within the plant, the weight of the plant is affected and decreases. Additionally, due to the disruption of nutrient balance and the effects of osmotic stress, growth is reduced, and the dry weight of the aerial parts also decreases.
Conclusion
In general, the results showed that the imposition of salt stress affected the growth and physiological traits of chickpea genotypes. Seed weight and plant dry weight decreased in all genotypes under salt stress conditions of 6 dS.m^-1 compared to the control treatment. The studied genotypes were able to maintain their survival and growth under salt stress conditions through various mechanisms such as increasing antioxidant compounds, preserving relative leaf water content, increasing leaf chlorophyll content, enhancing the activity of antioxidant enzymes, and increasing the content of metabolites. Generally, there was a high diversity among the studied chickpea genotypes, suggesting that their use in improving salt tolerance in chickpea plants could be beneficial.

Keywords

• Antioxidant
• Chlorophyll content
• Dry weight
• Enzyme
• Metabolite

Main Subjects

• Salinity stress