Effect of gamma amino butyric acid on morpho-physiological traits and seed yield of Quinoa under salinity stress

Salinity and accumulation of salts in the soil are one of the most important non-biological stresses that limiting agricultural production in arid and semi-arid regions of Iran. to minimize the effects of stress we can use the foliar application of gamma-aminobutyric acid (GABA). Therefore, due to the adverse effects of salinity stress on the growth and yield of many plants, including quinoa, it is necessary to use methods to increase plant resistance to improve growth, production, and crop yield. Therefore, the present study was conducted to study the effect of gamma-aminobutyric acid on reducing the effects of salinity stress and improving the quantitative and qualitative characteristics of quinoa

Two-factor factorial experiment in a randomized complete block design with three replications, was conducted during 2018-2019 in the research greenhouse of Imam Khomeini International University in Qazvin, Iran. The experimental factors included salinity of irrigation water at three levels (0, 8 and 16 dS / m sodium chloride) and GABA at five levels (0, 2.5, 5, 7.5 and 10 mM). Quinoa seeds were obtained from the Seed and Plant Breeding Research Institute. After seedling establishment in the four-leaf stage, salinity was applied by adding sodium chloride to irrigation water. Some morphological and physiological traits such as main stem diameter, number of spikes per plant, grain yield, 1000-seed weight, harvest index; SPAD, leaf relative water content, leaf water loss and membrane stability percentage were also measured.

The results showed that salinity had a reducing and significant effect on plant growth and development indices. Application of gamma-amino butyric acid improved the traits of SPAD, plant height, stem length, number of spikes, and harvest index. Therefore, foliar application of GABA under salinity stress conditions is recommended as a compatible osmolyte that reduces salinity damage in quinoa. The salinity × GABA interaction was significant for all traits except relative water loss, SPAD index, plant height and number of spikes per plant. At salinity of 16 dS / m, the best GABA treatment increased the leaf relative water content (10%), membrane stability index (29%), stem diameter (11%), 1000-seed weight (37%), grain yield (36 %), plant dry weight (70%), potassium content (58%), potassium to sodium ratio (168%) and decrease in sodium content (117%) compared to non-use of GABA conditions. The maximum leaf SPAD index (39.88), the highest plant height (55.15 cm), and the highest number of spikes per plant (15.03) were obtained in plants treated with 10 mM GABA.

Quinoa is a plant with very high nutritional value that can be an important part of our diet shortly. The results of this study showed that although this plant has a high resistance to salinity, but increasing the salinity of irrigation water caused a significant reduction in its growth and development, on the other hand, the use of GABA as a natural factor that improves plant resistance to biotic and abiotic stresses, was able to greatly compensate for the damage caused by saline water and significantly increase the resistance of quinoa to salinity.