Abstract

Context: Phenotypic plasticity is a valuable perspective to evaluate the genotype x environment interaction in an agronomic context of crop adaptation to stress. This work investigated the phenotypic plasticity of leaf, canopy, and agronomic traits in spring wheat. Objectives: Our objectives were to (i) quantify the phenotypic plasticity of physiological and agronomic traits, (ii) probe for correlations between the plasticity of these traits, and (iii) evaluate their role in stressful and favorable environments. Methods: We phenotyped 14 spring wheat genotypes grown in 16 Mediterranean-type environments, combining two sites in central Chile, two water regimes (rainfed and with supplemental irrigation), and four growing seasons (2015–2018). Phenotypic plasticity was calculated as the slope of reaction norms relating the trait for each genotype to the environmental mean of the trait. Results: The range of phenotypic plasticity was large for grain yield (slopes of reaction norms from 0.79 to 1.19) and shoot dry weight (0.90–1.15). High plasticity correlated with high yield, shoot dry matter, plant height, and spikes per m2 under irrigation, but not under drought. High plasticity of harvest index (HI) was associated with low HI in rainfed and irrigated crops. Plasticity in kernels per spike and thousand kernel weight were not correlated with the trait per se in either condition. The phenotypic plasticity of leaf gas exchange traits varied from 0.81 to 1.21. High plasticity in net assimilation and stomatal conductance were associated with the trait in irrigated but not in drought conditions. The plasticity of the fraction of intercepted PAR and leaf area index ranged from 0.88 to 1.13. High plasticity of the fraction of intercepted PAR correlated with poor performance in irrigated conditions, while high carbon isotope discrimination plasticity was linked to low carbon isotope discrimination under stress. Conclusions: Our study elucidates the substantial phenotypic plasticity of spring wheat genotypes across diverse Mediterranean-type environments. We observed varying degrees of plasticity in leaf, canopy, and agronomic traits, with notable correlations between plasticity and trait under different environmental conditions. Our findings underscore the importance of understanding the variation in phenotypic plasticity with trait, genotype, and environment for plant adaptation to stressful and high-yielding conditions.