Plasticity and compensatory mechanisms of the yield components of triticale in response to reduced nitrogen fertilization

Context and Objective Nitrogen is a critical and essential nutrient for crop yield, yet its excessive use poses environmental and economic challenges. In this study, we investigated how triticale (× Triticosecale Wittmack) yield components respond to reduced nitrogen fertilization in order to guide breeding of nitrogen-use efficient cultivars. Methods A diverse panel of 450 genotypes was evaluated under standard and low nitrogen conditions across three locations. Grain yield as well as the yield components – ears per square meter, grains per ear, and thousand-kernel mass – were measured and analysed using univariate and multivariate mixed models. Results and Conclusions Significant genotypic variation was observed for all traits under both nitrogen fertilization levels. Grain yield declined under low nitrogen, mainly due to a reduced number of ears per square meter. A slight increase in thousand-kernel mass may reflect enhanced assimilate availability per grain, possibly supported by late-season nitrogen release from soil mineralisation. In contrast, the number of grains per ear remained stable across nitrogen levels. Notably, genotypes with a similar reduction in grain yield under lower nitrogen fertilization can show substantial differences in the response of each of the yield components. Under both nitrogen conditions, the yield component traits were positively correlated with grain yield but showed negative correlations among each other, reflecting the competitive allocation of assimilates. Significance Collectively, these findings emphasize the need for breeding programmes to jointly optimize yield components, particularly ears per square meter and thousand-kernel mass, to develop stable, high-yielding triticale genotypes for different nitrogen conditions. A comprehensive understanding of yield components allows targeting the actual limiting processes in yield formation rather than inducing compensatory shifts among highly plastic components.