Self-compatibility in modern hybrids of sunflower (Helianthus annuus L.). Evidence comparing fruit set in open and self- pollinated (bag isolated) plants grown in two different locations.

ASTIZ, V.; IRIARTE, L.A; FLEMMER, A.; HERNÁNDEZ, L.F.

Helia

Institute of Field and Vegetable Crops, Oil Crops Department

Lugar: Novi Sad; Año: 2011 p. 129 - 138

1018-1806

The increase in sunflower yield due to the active participation of honey bees (Apis meliferaL.) in crop pollination has been demonstrated in previous studies. However, this fact is more evident in earlier commercial hybrids.There are reports that suggest that bees are not required in modern commercial hybrids where a high level of self-compatibility occurs.The purpose of this study was to define formation capacity of fully developed fruits (FDF) and incompletely developed fruits (IDF) in two modern sunflower hybrids exposed to open and closed pollination.Two hybrids, one of halfcycle and the other of short cycle, labelled HA and HB respectively, were sub-mitted to two pollination regimes: auto-pollination (bagged treatment) wherethe heads were covered with mesh bags from the first anthesis (FA) to the lastanthesis (LA), avoiding the action of pollinators and open pollination (opentreatment). The study was conducted during three consecutive years in two dif-ferent locations. In the first year, the experimental plots were located at theChacra experimental Barrow (Tres Arroyos; 38°20’ S; 60°13’ W) and in the second and third year at the experimental field of Universidad Nacional del Sur,(Bahía Blanca; 38°45’ S; 62°11’ W), reaching an average plant density of 60.000plants/ha. During the second year treatments were conducted only on the HAand during the third year only on the HB.The number of FDF and IDF, in the three experiments on both sites did not show significant differences among treatments. Nevertheless, a non-significant different response in the numberof FDF and IDF was observed during two years, probably as a result of changes in environmental conditions duringthe anthesis period.We conclude that, due to the effect of a high level of self-compatibility, nodifferences in the generation of fully developed fruits can be observed whenplants of modern commercial sunflower hybrids are excluded from pollinators.