Throughout history, agricultural sector in Indonesia has faced a shortage of land. As a result, we must take use of land that is still available, even if the conditions are unsuitable for plant growth, one of which is salinity-stressed land. Amaranth is a frequently cultivated plant in Indonesia (Amaranthus tricolor L.). This vegetable plant is commonly consumed as food due to its nutritional content and numerous health benefits. To cultivate amaranth on salinity-stressed land, additional nutrients are required to ensure that the plants continue to thrive. One of them is the provision of biofertilizers, a type of organic fertilizer that contains beneficial bacteria for plant growth. This study aimed to determinate the effect of biofertilizer application on the growth and diameter of the stem metaxylem of amaranth plants growing in a salinity-stressed environment. As a salinity stress treatment, NaCl was applied at doses of 0, 2500, 5000, 7500, and 10000 ppm. The diameter of the metaxylem was determined by making fresh preparations across amaranth stems. The biofertilizer application does not affect the height and number of leaves of the plant. However, as the dose of biofertilizer was increased, the value of the metaxylem diameter of the stem increased.

Amaranthus tricolor L. is a widely consumed and cultivated vegetable in Indonesia. Meanwhile, one of the agriculturally usable areas in the country is coastal land. However, the salinity in this land needs to be considered for proper plant growth, therefore, biofertilizer solutions are applied to enhance the growth of plants under salinity stress. This fertilizer is made from livestock urine and microbial strains. In this study, the biofertilizer was applied at a dose of 0, 10, 20, and 30 liters/ha while the stress treatment was carried out with NaCl at a concentration of 0, 2,500 5,000, 7,500, and 10,000 ppm. In addition, manure was also given as a basic fertilizer. The highest growth rate observed in the form of increase in plant height and number of leaves was found in the biofertilizer treatment of 30 and 0 liters/ha. Meanwhile, the highest mean total chlorophyll content was found in plants treated with a dose of 30 liters/ha. Based on the results, it was concluded that the application of biofertilizer affects the growth rate and chlorophyll content of spinach, but only at a certain concentration of salinity levels.