CONICET | Buscador de Institutos y Recursos Humanos

An extended assumption in maize breeding is that potential yield (Ymax) predicts yield (Y) under stress conditions (here, Ymin), justifying genotypic selection under moderately high-yielding environments. Moreover, it has been postulated that Y tolerance to stress is relatively independent on the main stressfactor involved in Y reduction (cross-tolerance). We carried out an analysis of four datasets from Argentine Federated Farmers network (2010/11, 2011/12 and 2012/13, 11 locations and >20 hybrids) and the National Institute of Agricultural Technology (INTA) (12 locations, 13 hybrids). No consistent relation was detected between Y max and Ymin (r2 < 0.14) in each dataset. Y stability assessed by the coefficient of variation positively related to Ymin (r2 > 0.68 across datasets) but not to Ymax. Depending on the dataset, 40?70% of the hybrids had a varying Y performance (from worse to better) compared with theaverage of all hybrids, with no consistent advantage of hybrids with high Ymax within the environmental range explored in the dataset. In order to assess the existence of cross-tolerance, INTA environments were divided into two groups: water-limited environments and environments exposed to other(s) type(s) of stress. While a relation was found between average yields (r2 = 0.64) of each hybrid in both environments, there was no relation for Y stability (r2 = 0.07). Taken together, our results suggest that: (i) a high Ymax is not a good indicator of high Y tolerance under stressful conditions; (ii) Y tolerance is related to high Y stability, which may or may not involve a Y penalty under high-yielding environments; (iii) around 50% of the genotypes have Y performance that is not consistently worse or better than the average throughout therange of environments explored and (iv) cross-tolerance to stress is a peculiar trait of some hybrids, but most of the hybrids analysed here do not show cross-tolerance.