Genetic parameters and selection of Brachiaria decumbens hybrids for agronomic traits and resistance to spittlebugs

Rogério Gonçalves Mateus,Fabrícia Zimermann Vilela Torres,Lucas Bearari Martins,José Raul Valério,Cacilda Borges Do Valle,Pedro Nelson Cesar Do Amaral,Sanzio Carvalho Lima Barrios

doi:10.1590/1984-70332015v15n4a39

Abstract

Abstract The objective of this work was to estimate genetic parameters for agronomic traits and resistance to spittlebugs in B. decumbens hybrids and to select the ones with best performance. For that, 324 hybrids were evaluated in field plots for agronomic traits and in the greenhouse for resistance to spittlebugs. Genetic variability amongst the hybrids was observed for all traits analyzed. The heritability estimates between genotypes means were higher than 0.52 for all agronomic traits and 0.98 and 0.99 for nymphal survival and nymphal period duration respectively. Hybrids with better performance than cultivar Basilisk for each individual trait were identified and also through a selection index combining all traits. Assigning weights to the different traits in the selection index did not significantly alter the rank for superior hybrids. Those were selected to continue on to the next phases of the breeding program.

Highlights

Brachiaria pastures are the basis of animal production in the tropics and in Brazil since they provide means of producing beef and milk in acid and poor soils
Significant difference for the effect of hybrids was observed for all the agronomic traits and resistance to pasture spittlebugs through the maximum likelihood test (p < 0.01)
This result indicates the presence of genetic variability among the hybrids of B. decumbens for all these traits which allows selection of superior hybrids for both groups of traits

Summary

Introduction

Brachiaria pastures are the basis of animal production in the tropics and in Brazil since they provide means of producing beef and milk in acid and poor soils. These forages played a major role in bringing progress to some regions through the establishment of seed production industries. Among the species widely used, B. decumbens has a sole cultivar, cv. According to Keller-Grein et al (1996), this cultivar is the best known and mostly widely used throughout the world. Its excellent adaptation to poor, acid soils and its palatable forage production in pastures that withstand high grazing pressure somehow counteracts its susceptibility to pasture spittlebugs (Valério et al 1996) and animal photosensitization (Lascano and Euclides 1996)

Objectives

Methods

Results