Use of a Structure-Function Plant Model to Assess the Morphogenetic Plasticity.--How does variation in phyllochron modify plant growth and development of Brassica napus in the GreenLab model?

摘要

A functional-structural model of winter oilseed rape (WOSR) has been developed to study plant morphogenetic plasticity, i.e. how processes of morphogenesis are adapted in response to environmental constraints. The phyllochron (time between emergence of two successive leaves) is one of the variables sensitive to environment. The aim of this article is to use model sensitivity analysis to quantify the impact of an increase or a reduction in phyllochron on plant growth and source/sink functioning. The WOSR model is based on an adaptation of the GreenLab model. The model calibration has been carried out on experimental data. Simulated variations of phyllochron are based on the range observed on several years and varieties. Plant growth is simulated from seedling to beginning of flowering. The maximal number of leaves on the main stem is supposed to be equal for all simulations independently of the phyllochron value. Reductions in the phyllochron reduced duration of growth, leaf surface, Leaf Projected Surface (LPS), and plant dry mass at the end of the growth cycle. For a given calendar date, number of leaves is significantly modified but not the produced biomass. At the opposite, an increase in phyllochron, increased duration of growth, leaf surface, LPS, and plant dry mass. The impact of phyllochron variations can be compensated by 5% change in Leaf Mass per Area (LMA). Consequences of the plasticity in the structure of the plant were assessed in terms of source/sink dynamics. Increase in leaf appearance rate decreased offer/demand, while its slow down increased it. This is the first step towards a comprehensive assessment of the interaction between structural plasticity and functioning.