Sunflower crop-wild hybrids: Identification and risks

Abstract

Wild sunflower, Helianthus annuus, is an open-pollinated species that can be a major weed in several crops. If it hybridizes with cultivated sunflower the following generations can generate crop-wild hybrids that could evolve into invasive populations. The objective of this study was to morphologically characterize F1 hybrids between inbred lines and wild sunflower, their F2, BC1 and BC2 progenies with domestic sunflower to assess the risk of these plants evolving into invasive biotypes. Crop-wild hybrids were easily identified as off-type plants. F1 plants were taller, branched with several heads, smaller disks and phyllaries, stigma and pale anthocyanins, and a longer flowering period compared to cultivated sunflower. None of the F2 plants were similar to wild sunflower plants, but morphologically closer to the cultivated materials. These results showed the improbability that crop-wild off-type plants give rise to plants morphologically similar to wild sunflowers and therefore the risk of developing invasive populations by their introduction.