Associations among Twenty Years of International Bread Wheat Yield Evaluation Environments

Abstract

al., 1996). CIMMYT bread wheat germplasm bred in Mexico by means of this shuttle is distributed globally Understanding the way different environments differentiate cultiin the Elite Spring Wheat Yield Trial (ESWYT). vars for yield allows the plant breeder to optimize choice of parents, germplasm screening, yield testing, and resource use within the targetIn an attempt to focus the wheat breeding effort at region. To determine the associations among yield testing environ-CIMMYT, the major wheat production zones have been ments, wheat (Triticum aestivum L.) yield data from 963 replicated divided into zones of similar agro-ecological adaptation trials sown across a 20-yr period were analyzed by means of pattern (Calhoun et al., 1994;Rajaram et al., 1994). Abdalla et analysis and the shifted multiplicative model (SHMM) to group sites al. (1997) examined durum (Triticum turgidum L.) within and across years. Pattern analysis identified four primary cluswheat yield trials sown at 40 different locations in 1990ters of sites and four representative locations within these clusters 1991 and concluded that test sites associated on the basis were identified by squared Euclidean distances. Group-1 represented of latitude and similar production constraints. Others primarily Mediterranean and West Asian locations and South Amerihave indicated the importance of identifying and tarcan sites. Group-2 was comprised of generally warmer sites in southern geting wheat germplasm to specific environments (Deand eastern Asia. Group-3 comprised higher rainfall locations in South America and eastern Africa and Group-4 represented cooler sites in Lacy and Lawrence, 1988; DeLacy et al., 1994; Peterson South America and West Asia. The respective key locations for each and Pfeiffer, 1989). These studies examined associations of the four groups were Sakha, Egypt; Quezaltenango, Guatemala; among locations by estimating genotype ϫ environ-Londrina, Brazil; and Pirsabak, Pakistan. The four key sites were ment interactions. then used to examine site clusters within each year by SHMM. The Two models have been used to study the effects of sites at Pirsabak and Sakha associated best across all global wheat-GEI on site groupings without crossover interaction growing regions where a combined total of 700 of 1117 (62%) pos-(COI). These are the shifted multiplicative model sible clusters with other global wheat locations were realized. This (SHMM) (Cornelius et al., 1992; Crossa et al., 1993, compared with 52% for Quezaltenango and 38% for Londrina. Factors 1996) and the site regression model (SREG) (Crossa with a primary influence on site clustering were cropping seasonand Cornelius, 1997). The SHMM has also been used

Identificación de mega‑ambientes para potenciar el uso de genotipos superiores de arroz en Panamá

“…Además, diversos autores desarrollaron métodos para el agrupamiento de los ambientes (Gauch Junior & Zobel, 1997;Annicchiarico et al, 2000;Atlin et al, 2000;Trethowan et al, 2003;Yang et al, 2005).…”

Identifying high yielding stable winter wheat genotypes for irrigated environments in Central and West Asia

“…Wheat (Triticum aestivum L.) in Central and West Asia is cultivated across diverse environments, ranging from warm lowlands to temperate highlands (Trethowan et al 2001(Trethowan et al , 2003Lage et al 2008). These environments represent more than one mega-environment for wheat cultivation as defined by CIMMYT (van Ginkel and Rajaram 1993).…”

Genetics Options for Improving the Productivity of Wheat in Water‐Limited and Temperature‐Stressed Environments

“…In crosses between primary synthetics and adapted wheat cultivars, plant breeders at CIMMYT observed an improved response to drought among the derived progeny (Trethowan et al 2000(Trethowan et al , 2003. These responses were initially observed in northwestern Mexico in the Sonoran desert under limited irrigation and then internationally once the selected progeny were distributed in CIMMYT's SAWYT (Lage and Trethowan 2008).…”

“…Materials developed and deployed in this way have adapted well to a wide range of growing conditions in the wheat-growing areas of the developing world (Trethowan et al , 2003.…”