Analysis of source and sink dynamics involved in oil and protein accumulation in sunflower achenes using a bi-linear model
Résumé
Most recent mechanistic crop models are based on source-sink relationships. To build a conceptual framework for achene quality traits in sunflower (Helianthus annuus L.), source-sink relationships were investigated in contrasting environments. Two experiments were performed under field conditions in 2011 and 2012. Oil, protein, hull (sink), leaves, receptacles and stems (source) were measured weekly under contrasting nitrogen (N−: no fertilization; N+: 150 kg N per ha), plant density (3 and 4.5 plants per m2) and genotype (cv. Kerbel, cv. LG5451 HO and cv. Olledy) treatments. A bi-linear model was fitted to source and sink component dry weight (DW) dynamics per m2. Nitrogen and plant density influenced rates and duration of all source and sink dynamics, while genotype had a significant influence on timing parameters. More significant factor interactions were found in 2011 than in 2012, probably because of other factors that occurred or interacted during grain filling (water stress and/or thermal stress). We constructed a robust source-sink framework for oil and protein accumulation in relation to remobilization processes. The observed “source” chronology was receptacles, stems and green leaves, and we confirmed the “sink” chronology of receptacles, hulls, protein and oil. Chronologies were influenced mostly by genotype. Such a framework is highly useful for dynamic modeling of sunflower. We also discuss the relevance and adaptability of the bi-linear model.