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Artifact Autogamy in Sunflower¹

Prior to the development of autogamous cultivars, cross-pollination was required for high yields of sunflower (Helianthus annuus L.). This research was undertaken to identify highly autogamous cultivars and to compare cloth and mesh bags in measuring autogamy for yield, achene weight, and achene oil percentage. Sixty-two cultivars in 1978 and 75 in 1979 were planted at Rosemount, Minn. Cloth or mesh bags were placed over 10 different sunflower heads in each cultivar plot to exclude Hymenoptera insects. Autogamy percentages were calculated from the achene yield/ha of the bagged heads times 100 divided by the achene yield/ha of the exposed heads. Weights/100 fertile: achenes and achene oil percentages from bagged and exposed heads were determined for each cultivar. ‘Peredovik#x2019; and #x2018;Sputnik#x2019; nonhybrid cultivars were low in autogamy both years whereas 28% of the hybrids in 1978 and 36% of the hybrids in 1979 were 100% autogamous for yield. Achenes from heads under bags were heavier than those from exposed heads, even in hybrids of 100% autogamy. Consequently, these hybrids had artifact autogamy and compensated for their partial autogamy by increasing weight/fertile achene. The increase in achene weights from bagging was accompanied by a decreaiie in achene oil percentages. This research indicates that hybrids with artifact autogamy may require insect pollinators for maximum oil concentrations. Either true or artifact autogamy is effective in maintaining achene yields/ha in the absence of insect pollinators. Mesh bags were less harmful to sunflower than cloth bags and consequently, preferable for determining artifact autogamy.

Key Words: Helianthus annuus L. • Sunflower breeding • Self compatibility • Cultivars • Oil percentage • Pollination • Achene weight • Yield

² Professor

Received for publication March 31, 1980.