Intercepted Solar Radiation during Seed Filling Determines Sunflower Weight per Seed and Oil Concentration

• Published in: Crop science 2003-01, Vol.43 (1), p.152-161
• Main Authors: Aguirrezábal, Luis A. N., Lavaud, Yorick, Dosio, Guillermo A. A., Izquierdo, Natalia G., Andrade, Fernando H., González, Leila M.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Crop management; Economic plant physiology; Environmental aspects; Environmental effects; Field tests; Flowers & plants; Fructification, ripening. Postharvest physiology; Fundamental and applied biological sciences. Psychology; Growth and development; Physiological aspects; Plant populations; Radiation; Seeds; Solar radiation; Sun; Sunflower seed
• ISSN: 0011-183X; 1435-0653
• DOI: 10.2135/cropsci2003.1520

A reduction in intercepted photosynthetically active radiation (PAR) during a short period of seed filling could affect weight per seed and oil concentration in sunflower (Helianthus annuus L.) depending when the reduction occurs. The main objectives of this work were (i) to determine the period of time during which intercepted PAR most influences final weight per seed and oil concentration, and (ii) to establish and validate relationships between intercepted PAR during such a period and oil yield components. Intercepted PAR was modified by shading (0, 50, or 80%) field grown crops during different periods of seed filling. Data from published and unpublished field experiments, in which intercepted PAR per plant was changed during the entire seed filling period by shading, thinning to reduce plant population, or both, were also used. All experiments were performed under adequate water and nutrient conditions. A reduction in intercepted PAR during 7 to 10 d of seed filling affected weight per seed and oil concentration. The developmental interval during which final weight per seed and oil concentration were best accounted for by accumulated intercepted PAR (r2 > 0.805) began at 250°C d and ended at 450°C days after flowering (DAF). The established relationships were validated with independent data. The relationships obtained in this work help to explain the effects of environment and crop management (sowing date, location, year) on oil yield variation.