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Stigma Receptivity and Seed Set in Protogynous Buffelgrass
- Shafer, Gail S., Burson, Byron L., Hussey, Mark A.
- Crop science 2000 v.40 no.2 pp. 391
- Cenchrus ciliaris, stigma, seed set, fecundity, inflorescences, flowering, cross pollination, pollen germination, pollen tubes, pollination, hybridization, gynoecium, ovules, styles, seed productivity, selfing, Texas
- Buffelgrass, (L.) Link syn = L., is an important warm-season perennial forage grass that is widely grown throughout the arid tropics. It has perfect florets, and emasculation is thought to be required to produce controlled hybrids. This is a tedious, difficult undertaking because of the small floret size. The flowering behavior of buffelgrass is such that the stigmas are exserted from the floret prior to anthesis, which is referred to here as the protogynous interval. This investigation was conducted to determine the duration of the protogynous interval in 447 buffelgrass accessions and to ascertain stigma receptivity during the protogynous intervals. Protogynous intervals in a field nursery near College Station, TX, for all accessions ranged from 1 to 4 d. Six accessions with protogynous intervals ranging from 1 to 3 d were used to investigate stigma receptivity under both self- and cross-pollinated conditions in a greenhouse. Pollen germination and tube growth were observed with fluorescent microscopy at different time increments following pollination. Across all accessions, pollen germinated within 15 min of contacting the stigma, and pollen tubes grew to the micropyle within 2 to 6 h, depending on the accession and pollen source. Mean seed set ranged from 11 to 76% and from 22 to 80% among accessions following self- and cross-pollination, respectively. This investigation revealed that variation exists for protogynous interval within buffelgrass, and the stigmas are receptive when exserted from the floret and remain receptive throughout duration of the protogynous interval regardless of whether it occurs 3, 2, or 1 d prior to anthesis. These findings demonstrate that protogyny can be used to produced controlled hybrids in sexual buffelgrass without emasculation.