Evidence for Heterosis in Italian Ryegrass (Lolium multiflorum Lam.) Based on Inbreeding Depression in F2 Generation Offspring from Biparental Crosses

Junping Wang,John Forster,Luke Pembleton,Noel Cogan

doi:10.3390/agronomy6040049

Junping Wang, John Forster + Show 2 more

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https://doi.org/10.3390/agronomy6040049

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Abstract

Italian ryegrass is one of the most important temperate forage grasses on a global basis. Improvement of both dry matter yield and quality of herbage have been major objectives of pasture grass breeding over the last century. F1 and F2 progeny sets derived from controlled pair-crosses between selected Italian ryegrass genotypes have been evaluated for yield and nutritive quality under field conditions. Linear regression of the performance of F1 families under sward conditions on parental genotype means in a spaced plant trial was significant for quality characteristics, but not for herbage yield. This result suggests that phenotypic selection of individual plants from spaced plant nursery is feasible for improvement of nutritive quality traits, but not for yield. The presence of significant heterosis within F1 populations was demonstrated by reduced herbage production in subsequent F2 populations (generated by one cycle of full-sib mating), an up to 22.1% total herbage yield in fresh weight, and a 30.5% survival rate at the end of the second reproductive cycle. Potential optimal crosses for exploiting such heterosis are discussed, based on construction and the inter-mating of complementary parental pools, for the implementation of a novel F1 hybrid production strategy.

Highlights

Italian ryegrass (L. multiflorum Lam.) is one of the most important temperate forage grasses on a global basis, providing a high quality and cost-effective option for the supply of forage during the winter and spring seasons
Three types of methods for first filial generation (F1 ) hybrid production have been proposed as a means to capture and exploit heterosis in forage grasses
The observed seasonal changes from of herbage yield andNursery quality are consistent with previous reports

Summary

Introduction

Italian ryegrass (L. multiflorum Lam.) is one of the most important temperate forage grasses on a global basis, providing a high quality and cost-effective option for the supply of forage during the winter and spring seasons. Forage productivity traits such as yield, quality, and persistence have been the core targets of modern ryegrass breeding [1]. Three types of methods for first filial generation (F1 ) hybrid production have been proposed as a means to capture and exploit heterosis in forage grasses These include varietal hybrid production [8,9,10,11], the use of Agronomy 2016, 6, 49; doi:10.3390/agronomy6040049 www.mdpi.com/journal/agronomy

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