Abstract
Producers need wheat cultivars adapted to the predominant climate conditions of the end of the rainy period. Having this in mind, EPAMIG (Agriculture and Livestock Research Institute of Minas Gerais) has been developing a wheat genetic improvement program since 1976, and the estimates of the genetic improvement established by the breeding programs could be useful to quantify their efficiency. This study focused on the quantification of the genetic progress achieved by these improvement programs of dryland wheat in the Brazilian-savanna between 1976 and 2005. The efficiency of these programs was evaluated based on grain yield data of VCU (Value for Cultivation and Use) trials conducted at ten locations in the Minas Gerais State, Brazil. The mean estimated genetic progress for mean grain yield between 1976 and 2005 was 37 kg ha-1 year-1. The genetic yield gain in the study period indicates that the improvement programs of dryland wheat in the Brazilian-savanna are effective. Besides the marked contribution of genetic gain, the environmental and technological improvements were also relevant for the yield, accounting for 47.4% of the total progress in the period. The improvement programs of dryland wheat resulted in a genotype renovation rate of 35% over the years.
Highlights
Since the seventies of the last century, wheat has expanded towards the Midwest of Brazil, where it is grown on soils of the Cerrado (Brazilian savanna) area, with quite promising results (Souza & Ramalho, 2001; Cargnin et al, 2006)
This study aimed to quantify the genetic improvement obtained by dryland wheat breeding programs in the Brazilian-savanna between 1976 and 2005, conducted by EPAMIG in Minas
A similar number was used in other studies on the genetic progress of other crops such as rice (Breseghello et al, 1999), shorter periods were by them considered in relation to the present case
Summary
Since the seventies of the last century, wheat has expanded towards the Midwest of Brazil, where it is grown on soils of the Cerrado (Brazilian savanna) area, with quite promising results (Souza & Ramalho, 2001; Cargnin et al, 2006). The planted area of dryland wheat is small, this crop type represents an alternative in succession to early soybean, as an income complement to producers, besides increasing land use efficiency and reducing machine idleness, among other advantages. As a rising number of soils has become infested by the soybean cyst nematode Heterodera glycines, new production systems are needed to be able to coexist with this new problem that threatens Brazilian soybean cultivation. Producers need wheat cultivars adapted to the predominant climate conditions of the end of the rainy.
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