Using stomatal aperture-related traits to select for high yield potential in bread wheat

More efficient wheat breeding methods are needed to meet demand for wheat from expected population growth in developing countries. This paper reports results from recent studies conducted at CIMMYT aimed at assessing the use of stomatal aperture-related traits (SATs) as indirect selection criteria for high yield-potential in bread wheat. Two classes of SATs were assessed: the instantaneous trait leaf porosity (POR), which is a close surrogate for stomatal conductance, and the integrative traits Delta C-13 ofleafandgrain and delta O-18 of grain. For 3 out of the 4 populations of breeding lines tested in 2001-02, the results indicated strong prospects for using SATs in screening for high yield potential. Grain A C-13, leaf A C-13 and POR each showed promise, with moderate to high heritability, moderate to strong genetic correlations with yield, and yield gains from retrospective selection of about 40-50g m(-2) at trial mean yields of 520g m(-2). Grain 6 (18) 0 showed less promise. Heritability of this trait was moderately high, but grain 8 O-18 was not strongly correlated with yield and retrospective gains from selection were small. For one population, none of the SATs showed any convincing association with yield. The reasons for this need further investigation as SATs are evaluated over additional seasons.