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Fertilization of an unreduced egg (2n + n) increases ploidy level and creates a new hybrid. It occasionally occurs in apomictic species but at a frequency too low to be a reliable method for genetic improvement. This investigation was undertaken to determine if 2n + n fertilization could be increased by early pollination. Six buffelgrass, Pennisetum ciliare (L.) Link [syn. Cenchrus ciliaris L.], accessions, five apomicts and one sexual, were self‐pollinated and cross‐pollinated with birdwoodgrass, P. ciliare (L.) Link var. setigerum (Vahl.) Leek, at 3, 2, 1, and 0 d before anthesis. The 2n + n progeny were identified by flow cytometry. DNA content (pg 2C−1) was determined for 1962 self‐pollinated and 3072 cross‐pollinated plants. Twenty‐eight self‐ and 80 cross‐pollinated plants had a higher DNA content and were products of 2n + n fertilization. The overall frequency of 2n + n fertilization when self‐ and cross‐pollinated was 1.4 and 2.6%, respectively. For all protogynous intervals, the frequency ranged from 0 to 5.2% for self‐pollinated plants and 0 to 8.2% for cross‐pollinated plants. When self‐pollinated, there was no correlation between time of pollination and recovery of 2n + n hybrids. When cross‐pollinated, there was a linear relationship between time of pollination and number of 2n + n hybrids recovered. More 2n + n hybrids were recovered from crosses made 2 or 3 d before anthesis. Thus in apomictic buffelgrass, the frequency of 2n + n fertilization can be increased by pollinating early, and in apomictic species where sexual germplasm is not available, this approach has potential to produce new apomictic hybrids.

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