Conceptual models of desirable trait profiles are used in wheat breeding to accumulate complementary physiological traits (PTs). The principal steps in PT breeding include characterization of potential parents for adaptive mechanisms, strategic crossing among parents that encompass as many target traits as possible, and early generation selection (EGS) of bulks for canopy temperature (CT). Other EGS techniques that are amenable to high-throughput include measurement of spectral reflectance indices and stomatal aperture-related traits. Exotic parents can be used to introduce new allelic diversity –including landraces and products of inter-specific hybridization– and both approaches have been employed to introduce stress-adaptive traits into CIMMYT germplasm. PT expression, even of un-adapted and exotic germplasm, can be used as a basis for selecting promising genotypes for use in germplasm development. Discovering the genetic basis of PTs is highly complex because putative quantitative trait loci (QTLs) may interact with environment and genetic background, including genes of major effect. Detection of QTLs is improved in mapping populations where flowering time is controlled, and new mapping populations can be designed by screening potential parents that do not contrast in Rht, Ppd or Vrn alleles. Association mapping can be employed for gene discovery using exclusively agronomically improved material.

Global Wheat Program

Text in English

INT1511

CIMMYT Staff Publications Collection