Document Type : Research Paper - Agronomy
Authors
1 Production and Genetics Department of Plant, Faculty of Agriculture, University of Birjand, South Khorasan Province, Birjand, Iran.
2 Manager of Saffron Research Group
3 Associate Professor, Production and Genetics Department of Plant, Faculty of Agriculture, University of Birjand, South Khorasan Province, Birjand, Iran.
4 Associate Professor, Department of Agrotechnology, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.
Abstract
Introduction: Environmental stresses are the most important factors limiting the growth and production of crops in the world. Among the environmental stresses, drought or water shortage is considered as the strongest and most sophisticated reducing factor for crop and food security threatening which is solely responsible for 45% of the reduction in crop yield in different parts of the globe. Drought stress and nutrient limitation, especially in arid and semi-arid conditions, have severe consequences on crop yield. Therefore, finding new solutions to increase the resistance of plants is essential. Quinoa is highly resistant to drought and salt stress and can grow well in soils with lack of nutrient. The high tolerance of this plant to abiotic stresses has made this plant highly adaptable to different climatic conditions. Therefore, quinoa can be used as a suitable plant for nutrition (i.e., food security) and achieving sustainable agriculture.
Material and Methods: The current study was performed in two experimental stations in Birjand and Mashhad, Iran, in 2019. Experiments were similarly conducted as the factorial split with four replicates. Irrigation regimes at 3 levels (50, 75, and 100% of water requirement) was the main plot and vermicompost (0 and 5 t. ha-1) × GABA (0, 5, and 10 mg L-1) were the subplot. Growth indices were measured in six stages and then the content of malondialdehyde, grain yield and amino acids were measured in full flowering stage and physiological ripening stage respectively.
Results and Discussion: According to the results of data analysis, increasing drought stress levels caused a decreased effect on plant height, Leaf Area Index (LAI), Crop Growth Rate (CGR), and Relative Growth Ra (RGR). For example, in the fourth stage (flowering stage) in Mashhad, after applying 5 t. ha-1 of vermicompost compared to control, CGR increased by 26.8%. The same results were recorded for isoleucine, lysine, phenylalanine, threonine, and tryptophan. A positive response regarding growth characteristics and amino acids in quinoa seeds was recorded following the application of vermicompost. Under severe drought stress, the application of GABA had a significant effect in reducing malondialdehyde content (15.6%), which is used as a marker to determine the amount of oxidative damage to lipids and the membrane damage. Based on the combined application of vermicomposting and GABA, the highest concentrations of isoleucine (5.25 mg L-1), lysine (6.20 mg L-1), methionine (2.19 mg L-1), and phenylalanine (3.21 mg L-1) were obtained when 5 t. ha-1 vermicompost + 10 mg L-1 GABA were tested.
Conclusion: In general, the use of GABA alone or in combination with vermicompost effectively decreased the adverse effects of drought stress on lipid metabolism and amino acid accumulation. According to the results, it is recommended the applying 5 t. ha-1 vermicompost + 10 mg L-1 GABA to improve quinoa resistance to water stress, especially under arid and semi-arid areas. Having this in mind, the widespread use of organic fertilizers can be considered as one of the essential areas in applied scientific research on sustainable agriculture development. Drought stress is also related to the plant nutrition, and a reduction in availability and various nutrients uptake for the plant is considered as one of the most important negative effects of drought stress. Therefore, using of natural fertilizers with biological origin has great importance in maintaining the structure, biological activity, exchange and water holding capacity and finally, in modifying the physical and chemical structure of soil.
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