Physiological Adaptation of Soybean Genotypes Induced with Gamma Irradiation against Drought

Dry land is characterized particularly by the limited water availabiliy and decreasing land productivity and the selection of drought tolerant genotypes is one of the strategies to optimize the productivity of agricultural crops on dry land. The study aims to classify soybean genotypes tolerant and sensitive to drought stress, determine the tolerance limits of the soybean genotypes to drought stress (the percentage of water content of soil) in growth and production on the dry land, and determine the parameters of observations that can be used as indicators for the selection of soybean genotypes tolerant to drought stress. The results are expected to give a contribution in the development of soybean on dry land. The research was carried out as experimental study using a Split Plot Design (SPD) with soil moisture levels as main plot (MP) and soybean genotypes as sub plot (SP). The soil moisture levels were set based on the percentage of soil water content consisted of four levels e. g.100 % field capacity (k0), 80-100 % field capacity (k1), 60-80 % of field capacity (k2) and 40-60 % of field capacity (k3). Soybean genotype mutants of the 4th generation used as the sub plot were Menyapa genotype, 50 Gy, Orba genotype, 25 Gy, Tanggamus genotype, Tanggamus genotype, 25 Gy, Tanggamus genotype, 50 Gy, Orba genotype, 50 Gy, Menyapa genotype, Orba genotype. A total of 32 treatment combinations were obtained and planted on acid dry land. The data was analyzed using statistical software (Excel). The result shows that six genotypes found to be tolerant namely genotype Menyapa, 50 Gy, Orba genotype, 25 Gy, Tanggamus genotype, Tanggamus genotype, 25 Gy, Tanggamus genotype, 50 Gy, Orba genotype, 50 Gy and 2 genotypes moderate, namely Menyapa genotype and Orba genotype. The percentage of soil moisture content of 40-60 % field capacity can be used as an indicator for selecting the soybean genotypes tolerant to drought, parameters of root length, root fresh weight and canopy, Al uptake in roots and canopy, proline content and the date of flowering can be used as indicators for selection of soybean genotypes to drought stress.