Relationship between vegetative organs functioning and sunflower grain filling

VAZQUEZ, ROCIO; BIANCULLI, M.; ECHARTE, M. M.; AGUIRREZÁBAL L.A.N

Toledo

Congreso; XXI reunión de la Sociedad Española de Fisiología Vegetal. XIV Congreso Hispano-Luso de Fisiología Vegetal; 2015

Sociedad Española de Fisiología Vegetal

Relationship between vegetative organs functioning and sunflower grain filling Rocío Vázquez 1, Mariana Bianculli2, Luis Aguirrezábal1,2, María Mercedes Echarte 1,2,31 Facultad de Ciencias Agrarias, Universidad Nacional de Mar del Plata, Argentina 2 Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)3 Instituto Nacional de Tecnología Agropecuaria (INTA)echarte.maria@inta.gob.arYield and quality of sunflower (Helianthus annuus L.) grains result from the combination of its genetic characteristics, the mother plant and the environment. Thus, final grain composition results from the overlapping of the kinetics of development and growth of both the plant and the grain. Environmental factors change grain composition both by directly affecting their metabolism and indirectly by altering mother plant functioning. Most of the knowledge on environmental effects on grain composition has been obtained studying mature grains composition. This approximation does not allow separating maternal, grain and environmental effects. Information of how the environment affects kinetics of plant and grain development and growth is scarce and the relationships between them have not been studied so far.Solar radiation intercepted by the plants is one of the main drivers of grain weight, oil concentration and quality (in terms of fatty acid composition). Its effects are mediated by changes in the assimilate availability for the grains (i.e. source/sink ratio). On the other hand, changes in intercepted radiation modify the onset and/or rate of leaf senescence. The aim of the present work is to explore the relationships between the response of oil concentration and quality of sunflower grain and the vegetative organs functioning under different source/sink ratio conditions.For this, sunflower hybrid MG2 (Dow Agrosciences) was grown in the field at Unidad Integrada Balcarce (Argentina). Treatments meant to increase source/sink (grain excision, E) or decrease it (shading, Sh) were applied. Vegetative organs functioning was evaluated along grain filling by measuring: photosynthesis, leaf area duration, profile of leaf N and chlorophyll, intercepted radiation per plant, NDVI and dry weight. Grain filling was characterized through oil yield components (grain weight and oil concentration) and grain chemical composition (fatty acid composition, C, N).Increasing source/sink increased intercepted solar radiation accumulated by increasing leaf area duration and slowing leaf senescence rate. E treatment reduced photosynthesis suggesting lower assimilate availability for the grains. Although it did not substantially affect grain weight, it decreased oil concentration and increased oleic acid percentage. Sh treatment decreased all the traits analyzed. C and N showed different partition to the grains depending on treatments. These results will be integrated in a conceptual model that will shed some light on the relationship between the performance of the mother plant and sunflower grain filling. This work was supported by CONICET (PIP0632), INTA (PNCyO) and UNMdP.