Environmental clues for yield performance and stability of Spanish bread wheat landraces

Breeding of bread wheat cultivars adapted to specific environments will be facilitated if ideotype characteristics associated with yield performance under such particular conditions can be determined. However, the existence of genotype-by-environment interactions (GEI) needs also to be examined for accuracy of cultivars performance expectations. In this study, we have field-assayed 60 spring bread wheat Spanish landraces under four contrasting environments. A detailed characterization of the environments has been conducted based on up to 40 agroclimatic variables. These included either climatic records, separately considering the vegetative and reproductive crop cycle, and bioclimatic variables that consider the combined effect of temperature and precipitation along the whole crop season. Grain yield (GY) and related components, i.e., spikes per m 2 (SN), kernels per spike (KS) and thousand-kernel weight (TKW), have been evaluated as well as some relevant agronomic traits (days to heading and plant height). The results have evidenced great differences among traits regarding the relative weight of the genotype and environment on total variation. It has also been showed that increasing a certain yield component can be associated to better yield performance in some, but not all, environments. The same holds for earliness, found to be irrelevant on GY in favourable agroclimatic conditions but showing beneficial effects on genotypes performance if cultivated in climatically adverse environments. The GEI for GY resulted much more influenced by the site than by the year factor and, among agroclimatic conditions, water inputs were less relevant than certain temperature records. Finally, individual local varieties with either good performance in contrasting conditions or restricted adaptation to any of the environments tested have been identified. • Increasing kernels per spike is the commonest strategy for achieving higher yields. • Spike number has no effect on yield in some environments. • Earliness has opposite effects on grain yield in stressed and favourable environments. • Warm temperature and water input in spring favour spike formation. • Water inputs are less relevant on G×E interaction than thermal conditions.