Evaluation of the Reaction of Early Genotypes of Quinoa Plant to Different Levels of Salinity Stress

Prolonged droughts and lack of water resources, followed by the salinity of water and soil resources, have faced many limitations in the production of some conventional agricultural and garden plants, especially in arid and semi-arid regions of the country. Therefore, the introduction of new plants with high yield potential, which have suitable growth in saline soils, the threshold of their seed yield reduction is high, and the production product is of high quality has been considered in Iran. Quinoa with the scientific name Chenopodium quinoa Willd. It is an annual plant originating from Latin America, which, despite its high nutritional value, tolerates a wide range of abiotic stresses and can grow in marginal lands. For this reason, this experiment was conducted to investigate the performance of quinoa plant genotypes against different levels of salinity in the research field of the Gorgan Agricultural Meteorological Research Department.

Cultivation of seeds of nine genotypes Titicaca (control number), Giza1, RedCarina, Q18, Q21, Q22, Q26, Q29, and Q31 obtained from Karaj Seedling and Seed Breeding Research Institute in a factorial experiment based on a complete random block design. Plastic pots were made with a bed of sand and clay in a ratio of two to one on March 5, 2019. The application of NaCl salt solution treatments at the levels of zero, 10, 20, and 30 decisiemens/m started after the establishment of the plant and reached the six-leaf stage and lasted for 45 days. After salinity treatment, morphological traits including plant height, stem diameter, number of sub-branches, inflorescence length, inflorescence width, biomass, 1000 seed weight, and seed weight per plant were measured.

According to this study, with the increase in NaCl salinity level, there was a significant decrease in all traits. Different genotypes also had significant differences in most traits in each salinity treatment. The RedCarina and Q12 genotypes consistently exhibited poor performance across all salinity levels in the examined traits, whereas the Giza1 and Q21 genotypes demonstrated high performance in most traits, indicating sensitivity and tolerance, respectively. These two groups of genotypes consistently clustered together in both cluster analysis and biplot tests across different salinity levels. However, some genotypes displayed relative performance variations at different salinity levels. For instance, the Titicaca cultivar excelled at high salinity levels of 20 and 30 dS.m-1, while the Q29 and Q31 genotypes exhibited high performance and tolerance to salinity stress at low salinity levels of zero and 10 dS.m-1. Genotypes that had high yield potential at low salinity levels had the highest yield in vegetative traits at salinity levels of 20 and 30 decisiemens, but had the lowest values in reproductive traits, especially in seed weight. In Principal Component Analysis, reproductive traits explained the most changes in high salinity levels. Salinity stress caused a significant decrease in most of the traits of the quinoa plant. The response of genotypes to different salinity levels was different. In addition, the genotypes showed different performance even in different growth phases. The high performance in traits related to the vegetative phase and weak response in the reproductive phase show that the granulation stage in the quinoa plant can be introduced as a salinity-sensitive stage. These results also show the high diversity of quinoa plant genotypes in each of the different salinity levels.