Black soybean (Glycine max L.) is native to Asia and well adapted to tropical climate countries, such as, Indonesia. The demand for black soybean supply increases due to soy sauce making. Limited fertile land causes efforts to enhance black soybean production to relocate to sub-optimal lands, such as, saline land. However, in saline soils the plant productivity is very low; therefore, technological inputs are required to prevent the crop from salinity stress, one of which is an exogenous application of antioxidants. The presented study aimed to analyze the yield in several black soybean cultivars when applied with antioxidants under salinity stress conditions. The study used a randomized complete block design with a factorial arrangement and three replications. The first factor comprised four cultivars of black soybean, i.e., Malika, Detam 2, Detam 3, and Detam 4, while the second factor was antioxidants (ascorbic acid, salicylic acid, and vitamin E – α-tocopherol) application, and without application of antioxidant (control). The results showed that salinity stress significantly affected the growth and yield of four black soybean cultivars. However, cultivar Detam 2 compared with other cultivars, performed best based on morphological and yield-related traits under saline soil conditions. Furthermore, in antioxidants, salicylic acid gave the best results for morphological characters, while ascorbic acid and vitamin E performed better for yield-related traits. Overall, the antioxidant application increased the tolerance of black soybean genotypes as compared with the control under salinity stress conditions.

Keywords: Black soybean (Glycine max L.), antioxidant defense, cultivars, morphological traits, NaCl levels

Key findings: Antioxidants play an essential role and increase the tolerance of black soybeans to salinity stress conditions.