Genetic Yield Gains In CIMMYT's International Elite Spring Wheat Yield Trials By Modeling The Genotype × Environment Interaction.

Leonardo A Crespo‐Herrera,Govindan Velu,Mateo Vargas,Suchismita Mondal,Julio Huerta‐Espino,Jose Crossa,Enrique Autrique,Hans J Braun,Ravi P Singh

doi:10.2135/cropsci2016.06.0553

Abstract

We calculated the annual genetic gains for grain yield (GY) of wheat (Triticum aestivum L.) achieved over 8 yr of international Elite Spring Wheat Yield Trials (ESWYT), from 2006–2007 (27th ESWYT) to 2014–2015 (34th ESWYT). In total, 426 locations were classified within three main megaenvironments (MEs): ME1 (optimally irrigated environments), ME4 (drought-stressed environments), and ME5 (heat-stressed environments). By fitting a factor analytical structure for modeling the genotype × environment (G × E) interaction, we measured GY gains relative to the widely grown cultivar Attila (GYA) and to the local checks (GYLC). Genetic gains for GYA and GYLC across locations were 1.67 and 0.53% (90.1 and 28.7 kg ha–1 yr–1), respectively. In ME1, genetic gains were 1.63 and 0.72% (102.7 and 46.65 kg ha–1 yr–1) for GYA and GYLC, respectively. In ME4, genetic gains were 2.7 and 0.41% (88 and 15.45 kg ha–1 yr–1) for GYA and GYLC, respectively. In ME5, genetic gains were 0.31 and 1.0% (11.28 and 36.6 kg ha–1 yr–1) for GYA and GYLC, respectively. The high GYA in ME1 and ME4 can be partially attributed to yellow rust races that affect Attila. When G × E interactions were not modeled, genetic gains were lower. Analyses showed that CIMMYT’s location at Ciudad Obregon, Mexico, is highly correlated with locations in other countries in ME1. Lines that were top performers in more than one ME and more than one country were identified. CIMMYT’s breeding program continues to deliver improved and widely adapted germplasm for target environments.

Highlights

We calculated the annual genetic gains for grain yield (GY) of wheat (Triticum aestivum L.) achieved over 8 yr of international Elite Spring Wheat Yield Trials (ESWYT), from 2006–2007 (27th ESWYT) to 2014–2015 (34th ESWYT)
The average GY of Attila ranged from 2.0 t ha–1 in ME4 (33th ESWYT) to 6.31 t ha–1 in ME1 (31st ESWYT), whereas for local check (LC), the average GY ranged from 2.6 t ha–1 in ME4 (33rd ESWYT) to 6.76 t ha–1 in ME1 (29th ESWYT)
Phenotypic correlations for GY were highly significant between ME1 and ME4 in the 28th, 29th, 31st, 33rd, and 34th ESWYTs (Fig. 2)

Summary

Introduction

We calculated the annual genetic gains for grain yield (GY) of wheat (Triticum aestivum L.) achieved over 8 yr of international Elite Spring Wheat Yield Trials (ESWYT), from 2006–2007 (27th ESWYT) to 2014–2015 (34th ESWYT). The Global Wheat Breeding Program at CIMMYT was founded to explore strategies for breeding widely adapted and highly stable wheat cultivars (Braun et al, 1996; Singh and Trethowan, 2007) These strategies include: (i) the exchange and selection of segregating populations in contrasting environments (shuttle breeding), (ii) multilocation testing at representative sites in the environments where wheat is grown, and (iii) germplasm evaluation under stressed and optimal conditions. As part of its multilocation testing strategy, CIMMYT distributes annual nurseries and replicated yield trials through an international collaborative network that includes more than 300 cooperators Such nurseries consist of newly developed lines targeted at certain environments (e.g., the ESWYT for optimal environments) or at achieving certain breeding goals. Detailed descriptions of these MEs can be found in Rajaram et al (1993), Hodson and White (2007), Braun et al (2010), and in an internet-based platform launched by CIMMYT (www.wheatatlas.org, accessed 10 Oct. 2016)

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