Agronomic performance and genetic dissimilarity of second-harvest soybean cultivars using REML/BLUP and Gower’s algorithm

Diego Nicolau Follmann,Antonio David Bortoluzzi Silva,Daniela Meira,Gustavo Henrique Demari,Velci Queiróz De Souza,Maicon Nardino,Alberto Cargnelutti Filho,Ivan Ricardo Carvalho,Tiago Olivoto,Carine Meier

doi:10.1590/1678-4499.20180194

Abstract

ABSTRACT The cultivation of second-harvest with soybean crop after first-harvest with maize crop has become an alternative to aggregate income to farmers in the South region of Brazil. However, there is little information about this cropping system in this region. The aims of this study were to: (i) evaluate the agronomic performance of soybean (Glycine max L.) cultivars growing in second-harvest during the summer; and (ii) evaluate the genetic divergence of the cultivars based on qualitative and quantitative traits. To do this, 18 soybean cultivars were evaluated in three field trials, sown during January in the northwestern region of Rio Grande do Sul state, Brazil. In each experiment, a randomized block design with four replicates was used. Five quantitative traits (representing the agronomic performance of the cultivars) and 12 qualitative traits (morphological descriptors) were assessed aiming at studying the genetic divergence. Variance components and genetic parameters were estimated using mixed models and BLUPs for genotypes were estimated for each quantitative trait. The cultivars FPS Iguacu RR and BMX Turbo RR have good agronomic performance and are, based on quantitative and qualitative traits, genetically distant. These cultivars have shown agronomic features that allow their cultivation in the second-harvest in the northwestern of Rio Grande do Sul in addition to be potential genitors for future soybean breeding programs.

Highlights

The area of soybean cultivation in Brazil is 35 million hectares, being Rio Grande do Sul the second largest producer state with a cultivated area of 5.69 million hectares (CONAB 2018)
Studies on soybean cultivation in the second-harvest in subtropical regions are still limited and should be fostered by research. It can be cited studies evaluating the agronomic performance of the soybean in late periods of cultivation in the southern region of Brazil, that evaluated the first-pod insertion height across sowing times, plant height, and mass of seeds (Braccini et al 2004), the number of branches (Ludwig et al 2010; Zanon et al 2015) and the grain yield (Ludwig et al 2010)
The choice of productive and divergent cultivars is recommended, reducing the effect of the narrow genetic base, which occurs in domesticated crops that undergo intense selections during their breeding

Summary

INTRODUCTION

The area of soybean cultivation in Brazil is 35 million hectares, being Rio Grande do Sul the second largest producer state with a cultivated area of 5.69 million hectares (CONAB 2018). Studies are reported in the literature to evaluate the morphological traits and genetic divergence of cultivars in specific cropping regions and conditions, such as genetic dissimilarity in a lowland environment in Tocantins (Almeida et al 2011), first-crop cultivation in the states of Rio Grande do Sul (Rigon et al 2012), Mato Grosso do Sul (Torres et al 2015), and Piauí (Sousa et al 2016), as well as in Tanzania (Lyimo et al 2017). The aims of this study were to: (i) evaluate the agronomic performance of second-harvest soybean cultivars (Glycine max L.) using mixed models; and (ii) evaluate the genetic divergence based on the Gower’s algorithm and UPGMA (Unweighted Pair-Group Method Using an Arithmetic Average) grouping, based on qualitative and quantitative traits

MATERIAL AND METHODS

Dissimilarity of second-harvest soybean cultivars

Findings

CONCLUSION