Caracterização de cultivares antigas e modernas de soja quanto a morfologia radicular

Abstract

Soybean is one of most important economic crop worldwide, feedstock in many feed products, beyond be source oil and protein. With the advancement of the breeding programs and better management practices, the grain yield increased along the years. However, the genetic gain in root development is not known. The aim of this study was evaluated the genetic gain in morphologic root system of the genotypes cultivated in south of Brazil. Twenty-five genotypes from different releasers were used, released between 1965 to 2011. The trials was conducted in a greenhouse, at the UTFPR University. The experimental units was composed by PVC pipes (100 mm), with a plastic bag used to support the soil and plants. Theses plastic bags were manufactured manually. Five seeds were seeding in each PVC pipe, and after the emergence, one plant was selected to compose the experimental unit. None fertilizer was used, and the cultural practices follow the technical recommendations for the crop. The evaluated characters were: dry mass of primary and secondary root and root height. Data was evaluated by the ANOVA analyses and mean comparisons by TUKEY test, with 5% of error probability. The analyses were performed with Genes software. The soybean breeding reduced the root system between years. A negative linear regression was observed for all evaluated characters from old genotypes to modern genotypes, where the dry mass of primary root was r=-0.003, dry mass of secondary root was r=-0.006 and root height was r=-0.47. The genotype Paraná (1998) presented the bigger weight of dry mass of primary root (1.01 g) To the root height the genotype BR 4 (1979) presented the bigger result (125 cm) and for the dry mass of secondary root, the genotype BR 16 (1987) presented the bigger result as compared of other genotypes (0.68 g).