A process-based model for leaf development and growth in hardneck garlic (Allium sativum).

Background and aims Phenology and morphology are two major aspects of crop growth models. A new process-based model built for hardneck garlic (Allium sativum) is presented, focusing on phenology and morphology processes and how they translate to whole-plant growth. The tight coupling between the two processes and their dynamic changes throughout the growing season were captured while incorporating storage effects and reproductive aspects unique to bulbous crops. Methods Non-linear temperature dependences of leaf development were integrated into the model and dynamically coupled with changes in leaf growth throughout the growing season. Bulb storage effects on leaf development and photoperiod effects on the vegetative-to-reproductive transition were also incorporated. The model was parameterized with data from a set of experiments and the literature, while its performance was tested with additional observations that had not been used for parameterization under a range of environmental conditions, management practices and cultivar choices. Key Results The model successfully captured the dynamic nature of leaf development and growth in garlic plants throughout the growing season. It simulated with reasonable accuracy the timing of leaf initiation, maturation and senescence, as well as changes in green leaf area over time. Most parameters were relatively stable across cultivars, and parameter sensitivity tests revealed the importance of bulb storage effects. Conclusions The model embodies a novel approach to capture the phenology and morphology of garlic under a range of environments, genotypes and management practices. The process-oriented nature of the model and inclusion of storage effects set the foundation for bulbous crop growth simulations, allowing the understanding and discovery of key processes that coordinate and integrate the dynamics of growth and development from organ to whole plant, with implications for crop improvement programmes while opening opportunities for modelling other bulbous crops.