Andrew Yoel

Current breeding efforts in soybean largely focus on identifying genotypes with high seed yield and large seed size. Our study applied a mutation using 250 Gy Gamma-Ray Irradiation to soybean cv. Anjasari. The variability in the M1 generation was identified, and the planting was continued to M2 M3, M4, M5 until M6 generation. The objectives of this research were to evaluate mutant lines exhibiting a good performance in yield and morphological characteristics that can support the yield component in M6 generation. This research was conducted from January 2019 to May 2019 at Ciparanje Experiment Station, Faculty of Agriculture, Universitas Padjadjaran, Jatinangor, West Java. The experiment was arranged in a Randomized Completely Block Design with fifteen mutant soybean genotypes as treatments with two replications within each treatment. The results showed several genotypes produced higher yield and better agro-morphological characteristics. The genotypes MR-33, MR-4A, and MR-2A showed significantly higher number of total pods per plant. Meanwhile, the genotypes MR-35A, MR-37, MR-23, MR-36A, MR-3A, MR-29A, MR-34A, MR-4A, MR-17, and MR-5A showed a higher value in weight of 100 seeds. The highest yield was observed in MR-29A and MR-23, which then will be used as the genotypes for multilocation test for stability. ton.ha-1) (United States Department of Agriculture, 2019). Mutation is either one way to induce variations in the context of plant breeding in soybean germplasm, especially in large seed characters and high yield. Based on the utilization of gamma radiation in vivo and in vitro, followed by their utilization in breeding programs, induced mutation is one of the secure ways to improve genetic diversity in many plants including in soybean (Yuliasti and Reflinur, 2017). The latest data showed more than 2600 mutant varieties with desirable quantitative and qualitative traits have been introduced. Laskar and Khan (2017) obtained favorite traits using physical mutagens in lentils and advocated the importance of induced mutations as one of the most effective and efficient approaches to regenerate and restore the genetic variability in lentils. Mutation breeding is probably an effective tool for generating variability in the existing varieties and selecting lines with desirable characters, which proved to be an ideal crop. In this study, the mutation carried out was by using a 250 Gy Gamma-Ray Irradiation to soybean cv. Arjasari. Irradiation was performed using Gamma cell 200 machine owned by the National Nuclear Energy Agency (BATAN). The variability in the M1 generation was identified, and the planting was continued to M2 M3, M4, and M5 generation. In M5 generation planted from September 2019 to December 2019, it was found that genotypes MR-35A, MR-37, MR-23, MR-36A, MR-22A, MR-33, MR-16A, MR-3A, MR-29A, MR-34A, MR-4A, MR-17, MR-2A, MR-5A, and MR-8A showed a higher performance in yield and yield component compared to Arjasari cultivar as a wild type. Our present study was conducted to obtain promising genotypes of mutant soybean in M6 generation showing high yield and better morphological characteristics as a yield component. The genotypes of M6 generation that have been selected in this study will be used as prospective genotypes for multilocation test for stability of high yield in the next generation. MATERIALS AND METHODS This research was conducted from January 2019 to May 2019 at Ciparanje Experiment Station, Faculty of Agriculture, Universitas Padjadjaran, Jatinangor, West Java at an altitude of 850 meters above sea level. The soil type of the research site is Ultisol. Fifteen mutant soybean genotypes were used as the materials in this experiment. Others materials used were cow manure, Urea fertilizers, KCl fertilizers, SP-36 fertilizers, fungicides (Karbofuran 3G), insecticides (deltametrin), water, and liquid organic fertilizer. This experiment was arranged in a Randomized Complete Block Design (RCBD) consisting of 15 genotypes as treatments with two replications within each treatment. Urea, KCl, and SP-36 fertilization was performed once in February and April, which was applied by making a patch on the side of the seeds planted in the field. The liquid organic fertilizer volume for each plot (1.2 m2) was 7.5 mL per plant, and it was applied every two weeks until the harvest period. Plant spacing for each plot was 15 cm ×40 cm. The variables observed in this study included plant height, total number of pods per plant, total number of seeds per plant, total number of branches per plant, and yield. The data were analyzed using the analysis of variance (ANOVA) and the Scott-Knott test at a level of α = 5%, performed in R studio 1.1. 463 (Jelihovschi et al., 2014) . RESULTS AND DISCUSSIONS Plant height and number of branches per plant Plant height is the parameter of plant growth frequently observed since it becomes the determinant for the yield quality, and it can be simply measured (Zhang et al., 2018). Xue et al. (2019) find that plant height is an essential trait in soybean, as taller plants may have higher yields but may also be at risk for lodging. In this study, there was no significant difference in the plant height based on the ScottKnott test results (Table 1). Total number of branches is the characteristic that has indirect effect on the seed yield (Faot et al., 2019). The various mutant soybean genotypes compared in this study showed significantly different number of branches based on the ScottKnott test (Table 1). Genotypes MR-22A, MR-34A, MR-4A, MR-2A, MR-5A, and MR-8A showed higher plant height compared to others. The number of branches generally have a strong positive correlation with the number of seeds and yield (Vu et al., 2019). It is because the increasing number of branches indicates an increasing number of pods per plant (Egli, 2013). Ilmu Pertanian (Agricultural Science) 118 Vol. 5 No. 3, December 2020