Mutants obtained by chronical gamma irradiation from a Kárpátalja local soybean variety: II. M₄ and M₅ generations

Summary

In Hungary in the last few years there has been a renewed interest in improving oil and/or protein content of the soybean crop, because these components have positive economic values both for the purchasers and the sellers. For this purpose mutant soybean germplasm was developed by pedigree method from a Kárpátalja local variety by 100–300 Gy chronical gamma irradiation to produce mutant soybean lines with an increased oil and/or protein content and acceptable agronomic performance. Chronical gamma irradiation increased the genetic variability of the oil content. In the M₄ generation, function index predicted up to 28% oil content in the irradiated Kárpátalja germplasm. Plants with 24.1 and 23.6% oil content were selected from the 150 Gy and the 100 Gy populations. Due to the limited genetic variation for protein content, no mutant genotypes with higher protein content were identified. In the M₅ generation, progenies of a superior plant with 23.6% oil content were homozygous for this characteristics, while progenies of a superior plant with 24.1% oil content were segregating. Their oil content ranged from 20.3 to 22.1%. Oil content had a moderate negative correlation with 1000-seed weight in both of the studied generations (r = −0.40*** and −0.39***). The 200 Gy dose significantly increased the number of pods, the number of seeds and the yield per plant. The applied doses, except the 150 and the 200 Gy ones, significantly decreased the 1000-seed weight as compared to the control. A function index was introduced to evaluate the genetic variability. The seed yield performance at two locations showed significant differences.