Effect of Selenium and Humic Acid on Germination and Some Morphological Characteristics of Quinoa under Drought and Salinity Stress

In recent years, young quinoa leaves are used as fresh or cooked vegetables. Due to its high quality vegetable protein, quinoa is a promising candidate for increasing food production in the world. Due to its tolerance to abiotic stresses, quinoa is known as one of the most valuable and nutritious food products. Environmental stresses, especially drought and salinity are one of the most important factors in reducing growth in plant growth and development stages, especially the germination stage of the plant. The increase in global demand for the production of nutritious and healthy food has challenged researchers to look for the production of products in marginal areas that are inefficient for producing agricultural products due to adverse weather conditions, low soil fertility, and lack of good quality irrigation water. As a result, in this study was conducted to study the effect of selenium and humic acid on germination percentage, seed germination characteristics and some morphological characteristics of quinoa (Chenopodium quinoa) seedling under drought and salinity stress as a factorial experiment in the form of completely randomized design with three replications.

The research was conducted as two independent experiments. The experiments were  carried out in the physiology laboratory of the Faculty of Agricultural Sciences and Engineering. The first experiment consisted of four levels of selenium (0, 5, 10 and 20 mg L-1 sodium selenate), three levels of humic acid (0, 100 and 300 mg L-1) and four levels of drought stress (0, -4, -8 and -12 bar). The second experiment with four levels of selenium (0, 5, 10 and 20 mg L-1 sodium selenate), three levels of humic acid (0, 100 and 300 mg L-1) and six levels of salinity stress (0, 0.5, 4.3, 8, 11.8 and 16 ds/m) were performed. Titicaca variety was used in this research. The criterion for seed germination was the emergence of roots approximately 3 mm long. At the end of the seventh day, the characteristics of germination percentage, germination rate, mean daily germination, mean germination time, germination rate coefficient, seed vigour and seed germination index were measured. At the end of the experiment, the length, fresh and dry weight of seedlings, stems and roots were examined.

Drought and salinity stress had a negative effect on germination percentage and seed  germination indices and morphological characteristics of quinoa seedlings. Whiles, according to the results, selenium and humic acid under salinity and drought stress had a positive effect on germination percentage and some morphological characteristics of quinoa seedling. Considering that one of the salinity resistance indicators is having longer root length, selenium and humic acid increased the root length of quinoa under salt stress conditions compared to the control. Humic acid and selenium had a positive effect on germination and plant growth by increasing water uptake and root volume, so that the highest germination percentage and morphological characteristics in the treatment without stress with 20 mg L-1 sodium selenate and 300 mg L-1Humic acid was observed. According to the obtained results, the highest percentage of germination, germination rate germination rate coefficient, seed vigor, seedling, stem and root fresh weight in the treatment without salt stress with 20 mg L-1 of sodium selenate and 300 mg L-1 humic acid was observed. With the increase of sodium chloride concentration, the germination percentage and germination indices of quinoa seeds decreased. Under salinity stress, in all four levels of selenium, with increasing humic acid concentration, the percentage of germination and investigated characteristics increased.

Therefore, the use of humic acid at a concentration of 300 mg L-1 along with 20 mg L-1 sodium selenate is recommended to improve germination and seed growth of quinoa under drought and salt stress conditions. As a result, the use of selenium and humic acid in the direction of sustainable agriculture and healthy crop production is cost effective and the use of selenium and humic acid fertilizer is recommended. Humic acid improves product performance by increasing nutrient absorption and affecting antioxidant defense mechanisms. In salinity stress, humic acid leads to osmotic regulation by maintaining water absorption. Selenium has beneficial effects on plants at low levels. Selenium can affect germination and root length. Plant seeds are able to absorb selenium from the environment and convert it into various organic forms or inorganic selenium compounds during germination.