Strengths and Weaknesses of National Variety Trial Data for Multi-Environment Analysis: A Case Study on Grain Yield and Protein Content

Vahid Rahimi Eichi,Paul Eckermann,Peter Langridge,Benoit Darrier,Matteo Riboni,Trevor Garnett,Mamoru Okamoto

doi:10.3390/agronomy10050753

Abstract

Multi-environment trial studies provide an opportunity for the detailed analysis of complex traits. However, conducting trials across a large number of regions can be costly and labor intensive. The Australian National Variety Trials (NVT) provide grain yield and protein content (GPC) data of over 200 wheat varieties in many and varied environments across the Australian wheat-belt and is representative of similar trials conducted in other countries. Through our analysis of the NVT dataset, we highlight the advantages and limitations in using these data to explore the relationship between grain yield and GPC in the low yielding environments of Australia. Eight environment types (ETs), categorized in a previous study based on the time and intensity of drought stress, were used to analyze the impact of drought on the relationship between grain yield and protein content. The study illustrates the value of comprehensive multi-environment analysis to explore the complex relationship between yield and GPC, and to identify the most appropriate environments to select for a favorable relationship. However, the NVT trial design does not follow the rigor associated with a normal genotype × environment study and this limits the accuracy of the interpretation.

Highlights

Wheat is a major source of protein in the human diet and, along with rice, the most important crop product for carbohydrate [1,2]
While grain yield is of critical importance to wheat farmers, the protein content will influence the value of the grain
The relationship between grain yield and protein content is complex and highly dependent on the production environment but breeders have targeted both traits for selection in their breeding programs

Summary

Introduction

Wheat is a major source of protein in the human diet and, along with rice, the most important crop product for carbohydrate [1,2]. Through advances in agronomic practices and breeding, wheat yields have increased spectacularly over the past few decades [2,4,5]. Many of the major traits, such as yield and GPC, targeted for improvement in breeding programs and of prime importance to farmers, are under complex genetic control and strongly influenced by the production environment. For both wheat breeders and farmers, the relationship between yield and GPC is important. Many countries run extensive varietal trials to provide information for farmers on performance of varieties under their likely production conditions and for Agronomy 2020, 10, 753; doi:10.3390/agronomy10050753 www.mdpi.com/journal/agronomy

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