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Wheat Yield Improvements in Brazil: Roles of Genetics and Environment
Author(s) -
Bornhofen Elesandro,
Todeschini Matheus Henrique,
Stoco Matheus Giovane,
Madureira Alana,
Marchioro Volmir Sergio,
Storck Lindolfo,
Benin Giovani
Publication year - 2018
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci2017.06.0358
Subject(s) - genetic gain , biology , randomized block design , yield (engineering) , breeding program , grain yield , restricted maximum likelihood , best linear unbiased prediction , agriculture , agronomy , gene–environment interaction , variance components , microbiology and biotechnology , zoology , genetic variation , statistics , genotype , selection (genetic algorithm) , cultivar , ecology , genetics , mathematics , maximum likelihood , gene , materials science , artificial intelligence , computer science , metallurgy
Several studies have shown a significant increase in wheat ( Triticum aestivum L.) grain yield (GY) worldwide during the 20th century as a result of genetic and environmental improvement. The objective of this study was to measure the genetic gains achieved in a wheat breeding program maintained by the Central Cooperative of Agricultural Research (COODETEC) in Brazil through the annual evaluation of lines in multienvironment trials. The dataset was composed of 836 advanced trials and was evaluated in 40 representative locations to assess the value for cultivation and use (VCU) regions in the south, southeast, and central‐west areas of the country from 2004 to 2013. Each trial consisted of 25 treatments (lines + checks) in a randomized complete block design with three replicates. A linear mixed model was fitted to predict the genetic values of each genotype per year and a restricted maximum likelihood algorithm to estimate the variance components. These genetic values were used to compute the genetic gain over the years. The overall estimated genetic gain of the breeding program was 61.59 kg ha −1 yr −1 (1.68% yr −1 ) for GY, although it was partially counterbalanced by the estimated negative environmental effects. The genetic gain per VCU region ranged from 31.38 (VCU 4) to 115.33 kg ha −1 yr −1 (VCU 1). After accounting for the environmental changes over years, the yield gain was 39.40 kg ha −1 yr −1 (1.10% yr −1 ), ranging from −0.82 (VCU 3) to 3.35% yr −1 (VCU 1). The assessment of Brazilian cultivars released between 1998 and 2014 showed genetic gains in GY of 34.8 kg ha −1 yr −1 (1% yr −1 ), demonstrating that the efforts of Brazilian research institutions to develop cultivars have produced additive results. The implications of genetic gain estimates on breeding programs are discussed.