Patterns of carbohydrates storage in sunflower cultivated at contrasting light enviroments

MARTÍNEZ NOËL G; GIORGI ME; DOSIO G; GARCÍA L; TOGNETTI J

Corrientes

Congreso; XXXII RAFV XVI CLAFV; 2018

In irrigated sunflower, C fixed before anthesis provides about 15 % of total grain C uptake. Carbohydrates are assumed to be stored as sugars mainly in stem, although precise studies about other organs, or under increased assimilate availability, are lacking. We studied the sunflower carbohydrate storage pattern under contrasting light environments.VDH 481 (Advanta) seeds were field cultivated without water or nutrient limitations at 7.2 plants m-2 (controls); after emergence, half of the plot was thinned to 0.48 plants m-2 (isolated). Aboveground structural dry mass (ASDM) and combined fructose (CF, stored carbohydrates) were measured at anthesis in stem, leaves (at different layers), and receptacle. ASDM of isolated plants was 115 % higher than in controls, due to mass increases (80 - 129 %) in all plant organs, while stored CF was 162 % higher, mainly due to heavy sugar accumulation in receptacle. Stem contributed less than receptacle to total CF, especially in isolated plants, in which stem sugars only accounted for 21% of total CF. Thus, both increased mass of storage organs and receptacle CF concentration explained the larger sugar accumulation in plants at higher light availability. This was associated with 55 % higher grain yield of isolated plants.