Cultivation interruptions reduce fitness without consistently increasing phenotypic plasticity in an evolutionary...

Phenotypic plasticity can buffer environmental change, but its evolution depends on cue reliability, fitness costs, genetic variation, and the duration of selection. We developed an individual-based Trait-Environment Fitness Interaction (TEFI) model to examine how cultivation interruptions affect absolute fitness and reaction-norm evolution. During interruptions, selection, reproduction, and mutation ceased, while damage accumulated and decayed after cultivation resumed. Across 100 replicate populations per scenario, long interruptions produced substantially lower final fitness than continuous cultivation. Seed-matched analyses showed lower mean fitness after intermediate and long interruptions, whereas 95% paired intervals for short and recurrent interruptions included zero. None of the baseline interruption scenarios clearly increased mean or final plasticity. Duration experiments, mechanism ablation, genetic-correlation tests, environmental controls, and global sensitivity analysis showed that the fitness response was robust, whereas the plasticity response was conditional. Damage and incomplete recovery contributed to the long-interruption fitness decline, whereas the direct cost of evolved plasticity contributed little. A clear plasticity increase occurred only when long interruptions were combined with strong directional environmental change. Across seven crop datasets, normalized plasticity was lower in rice and wheat than in the other five crops (difference = 0.102, hierarchical-bootstrap 95% interval: 0.072-0.177; exact one-sided permutation P = 0.0476), with the direction robust to alternative metrics and leave-one-dataset-out analyses. This provides a quantitative consistency test, not crop-specific validation of TEFI. Our results identify interruption duration, environmental direction, and recovery opportunity as determinants of post-interruption fitness and caution against assuming that cultivation interruption universally promotes greater plasticity.