Identification of superior progenies between common bean gene groups for root system obtained by recurrent selection

Paulo Henrique Cerutti,Ana Carolina Da Costa Lara Fioreze,Altamir Frederico Guidolin,Jefferson Luís Meirelles Coimbra,Jucimara Alves Silva,Rita Carolina De Melo,Silmar Primieri

doi:10.1590/1678-4499.20200487

Abstract

Genetic variability is essential for gains in breeding programs. The cyclic process of progeny recombination is a strategy to raise the chances of selecting better genotype combinations. The objective of this study was to identify superior progenies between common bean genes groups in first recurrent selection cycle for root system traits. Parents of the Andean and Middle American gene groups were hybridized in a complete diallel scheme. Thereafter, the parents and F1 and F2 populations were planted in the field. To establish the base population of recurrent selection (C0), seven segregating populations (F2) with superior performance for root system were selected and intercrossed, resulting in recombinant progenies (C1). To estimate the selection gain, the parents and C0 and C1 genotypes were compared with regard to the following variables: total root length (TRL, cm), projected root area (PRA, cm2), root volume (VOL, cm3) and number of root tips (RT). The difference between genotype combinations indicates the presence of genetic variability and effectiveness of recurrent selection. The mean genetic progress for root system-related traits was 12.9% (TRL), 12.6% (PRA), 12% (VOL) and 11.5% (RT) in the first recombination cycle. The mean phenotypic performance of seven of the C1 progenies exceeded that of their parents for all root system traits. These progenies are promising as base populations of the next selection cycle.

Highlights

Over the course of time, breeding programs have been successful in the development of agronomically superior genotypes
The mean square value of genotypes was significant by the F statistic (p < 0.05) for all response variables (Table 2). This fact reveals the existence of genetic variability among the 35 genotypes
Monitoring and use of genetic variability are fundamental at the beginning of any breeding program

Summary

Introduction

Over the course of time, breeding programs have been successful in the development of agronomically superior genotypes. For common bean (Phaseolus vulgaris L.), as well as other crops, breeding efforts have mainly addressed higher grain yields (Silva et al 2013; Pereira et al 2016). Due to the yield instability of common bean cultivars under adverse cultivation conditions, the root system has come to be considered a key aspect to be evaluated in breeding programs (Amongi et al 2015; Silva et al 2016). The presence of genetic variability and the low targeting of breeding programs for root system trait makes genetic gain possible. The Andean gene group comprises genotypes with large seeds (35–50 g/100 seeds), ‘T’ phaseolin type and growth habits I and IV. The Middle American group, on the other hand, includes genotypes with small seeds (20 g/100 seeds), ‘S’ phaseolin type and growth habits II and III. A predominantly superficial root system (0–10 cm) was reported for the Andean group, while root development into deeper soil layers was observed in the Middle American group (Nienhuis and Singh 1988; Beebe et al 2013; Polania et al 2016)

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Conclusion