1- Urmia University
Abstract: (7 Views)
Introduction and Objective: Bread wheat (Triticum aestivum L.), as one of the most important cereal crops worldwide, plays a fundamental role in providing both protein and calories for humans. However, the deficiency of micronutrients, particularly zinc (Zn), is recognized as one of the most serious challenges in wheat production and grain quality. Zinc functions as a cofactor for numerous enzymes and has a pivotal role in many essential biological processes, including photosynthesis, nitrogen metabolism, protein synthesis, and regulation of oxidative balance. Zn deficiency not only reduces crop yield but also limits the nutritional value of wheat grains, which adds to its importance from the perspective of human health and global food security. In this context, the exploitation of wheat genotypes with higher efficiency in zinc uptake and utilization can be considered a sustainable strategy to mitigate these limitations. Therefore, the present study was conducted to investigate the effects of soil Zn deficiency on morphophysiological traits, enzyme activities, and amino acid composition in wheat genotypes with contrasting zinc efficiency, to identify the underlying mechanisms of their differences, and provide a basis for selecting efficient genotypes to be used in breeding programs
Material and Methods: This study was conducted in autumn and winter 2023–2024 in the greenhouse of the Faculty of Agriculture, Urmia University, using a factorial design in a completely randomized layout with three replications. Factors included two zinc levels (no zinc application and 5 mg Zn kg⁻¹ soil from zinc sulfate), seven wheat cultivars (Niknejad, Kavir, Amin, Setareh, Owj, Sarang, and Farin), and three sampling stages (vegetative, reproductive, and grain-filling). The traits measured included plant height, stem diameter, awn length, root length and volume, root fresh and dry weight, spike length and diameter, grains per spike, total number of spikes, total spike weight, thousand-grain weight, and final grain yield. The shoot zinc efficiency index was calculated to identify Zn-efficient and Zn-inefficient cultivars. Additionally, zinc concentrations in roots, leaves, and grains, copper concentration in grain, activities of superoxide dismutase (SOD) and alkaline phosphatase(ALP), and concentration of essential (lysine, threonine, leucine, and isoleucine) and non-essential (aspartic acid, asparagine, arginine, glycine, and tyrosine) amino acids were determined in both efficient and inefficient genotypes. Data were analyzed using SAS software, and mean comparisons were performed with Duncan’s multiple range test.
Results: Based on the shoot zinc efficiency index, Niknejad was identified as the most Zn-efficient, while Farin was classified as the least Zn-inefficient. Analysis of variance showed that Zn deficiency significantly affected most traits at the 1% probability level. Under Zn deficiency, root length and weight, spike length, grains per spike, and yield of Farin were severely reduced, whereas Niknejad maintained its growth potential. Zinc concentrations in roots and grains of Niknejad under stress were significantly higher than those in Farin, whereas differences in shoot zinc levels were less pronounced. Grain copper concentration declined more sharply in the inefficient cultivars compared to the efficient ones. Enzyme activity analysis revealed that Zn deficiency decreased SOD activity in both cultivars, but Niknejad maintained significantly higher activity. The activity of alkaline phosphatase increased in the leaves of Niknejad under Zn deficiency, while no significant changes were observed in the roots of the cultivars. Amino acid analysis showed a reduction in both essential (lysine, threonine, leucine, and isoleucine) and non-essential (aspartic acid, arginine, glycine, and tyrosine) amino acids under Zn deficiency. For example, lysine and threonine concentrations in Niknejad under Zn sufficiency conditions were 14.8 and 11.5 mg g⁻¹, respectively, which decreased to 9.7 and 9.5 mg g⁻¹ under deficiency conditions.
Conclusion: The results showed that the Niknejad cultivar (Zn-efficient) has a higher ability to adapt to Zn deficiency compared to the Farin cultivar (Zn-inefficient). The Niknejad cultivar was able to maintain root and spike growth, the number of grains per spike, and yield even under Zn deficiency conditions, while the Farin cultivar exhibited a significant reduction in these traits. Study the activity of SOD and ALP enzymes in leaf and root indicated that the Zn-efficient cultivar, through increasing the activity of these enzymes, is capable of sustaining oxidative balance and improving Zn utilization, whereas the Zn-inefficient cultivar, under the influence of Zn deficiency, faced a reduction in enzyme activity. Furthermore, zinc concentration in the root and zinc and copper concentrations in the grain of the Zn-efficient cultivar were higher, which demonstrates a higher efficiency in the uptake, translocation, and remobilization of nutrients in these cultivars. In addition, the study of amino acids revealed that zinc deficiency led to a reduction in the concentration of both essential and non-essential amino acids in the grain of the Niknejad cultivar. In total, the findings of this research indicate that the selection of Zn-efficient cultivars can be an effective strategy for coping with Zn deficiency in soil. These cultivars, in addition to enhancing yield stability under Zn deficiency stress, also improve the nutritional quality of the grain and can be utilized as valuable genetic resources in breeding programs and in the development of new wheat cultivars.
Material and Methods: This study was conducted in autumn and winter 2023–2024 in the greenhouse of the Faculty of Agriculture, Urmia University, using a factorial design in a completely randomized layout with three replications. Factors included two zinc levels (no zinc application and 5 mg Zn kg⁻¹ soil from zinc sulfate), seven wheat cultivars (Niknejad, Kavir, Amin, Setareh, Owj, Sarang, and Farin), and three sampling stages (vegetative, reproductive, and grain-filling). The traits measured included plant height, stem diameter, awn length, root length and volume, root fresh and dry weight, spike length and diameter, grains per spike, total number of spikes, total spike weight, thousand-grain weight, and final grain yield. The shoot zinc efficiency index was calculated to identify Zn-efficient and Zn-inefficient cultivars. Additionally, zinc concentrations in roots, leaves, and grains, copper concentration in grain, activities of superoxide dismutase (SOD) and alkaline phosphatase(ALP), and concentration of essential (lysine, threonine, leucine, and isoleucine) and non-essential (aspartic acid, asparagine, arginine, glycine, and tyrosine) amino acids were determined in both efficient and inefficient genotypes. Data were analyzed using SAS software, and mean comparisons were performed with Duncan’s multiple range test.
Results: Based on the shoot zinc efficiency index, Niknejad was identified as the most Zn-efficient, while Farin was classified as the least Zn-inefficient. Analysis of variance showed that Zn deficiency significantly affected most traits at the 1% probability level. Under Zn deficiency, root length and weight, spike length, grains per spike, and yield of Farin were severely reduced, whereas Niknejad maintained its growth potential. Zinc concentrations in roots and grains of Niknejad under stress were significantly higher than those in Farin, whereas differences in shoot zinc levels were less pronounced. Grain copper concentration declined more sharply in the inefficient cultivars compared to the efficient ones. Enzyme activity analysis revealed that Zn deficiency decreased SOD activity in both cultivars, but Niknejad maintained significantly higher activity. The activity of alkaline phosphatase increased in the leaves of Niknejad under Zn deficiency, while no significant changes were observed in the roots of the cultivars. Amino acid analysis showed a reduction in both essential (lysine, threonine, leucine, and isoleucine) and non-essential (aspartic acid, arginine, glycine, and tyrosine) amino acids under Zn deficiency. For example, lysine and threonine concentrations in Niknejad under Zn sufficiency conditions were 14.8 and 11.5 mg g⁻¹, respectively, which decreased to 9.7 and 9.5 mg g⁻¹ under deficiency conditions.
Conclusion: The results showed that the Niknejad cultivar (Zn-efficient) has a higher ability to adapt to Zn deficiency compared to the Farin cultivar (Zn-inefficient). The Niknejad cultivar was able to maintain root and spike growth, the number of grains per spike, and yield even under Zn deficiency conditions, while the Farin cultivar exhibited a significant reduction in these traits. Study the activity of SOD and ALP enzymes in leaf and root indicated that the Zn-efficient cultivar, through increasing the activity of these enzymes, is capable of sustaining oxidative balance and improving Zn utilization, whereas the Zn-inefficient cultivar, under the influence of Zn deficiency, faced a reduction in enzyme activity. Furthermore, zinc concentration in the root and zinc and copper concentrations in the grain of the Zn-efficient cultivar were higher, which demonstrates a higher efficiency in the uptake, translocation, and remobilization of nutrients in these cultivars. In addition, the study of amino acids revealed that zinc deficiency led to a reduction in the concentration of both essential and non-essential amino acids in the grain of the Niknejad cultivar. In total, the findings of this research indicate that the selection of Zn-efficient cultivars can be an effective strategy for coping with Zn deficiency in soil. These cultivars, in addition to enhancing yield stability under Zn deficiency stress, also improve the nutritional quality of the grain and can be utilized as valuable genetic resources in breeding programs and in the development of new wheat cultivars.
Keywords: Alkaline phosphatase, Amino acid, Bread wheat, Micronutrients, Superoxide dismutase, Zinc efficiency
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