Influence of temperature and photoperiod on flowering and seed set in buffelgrass

Abstract

Lack of winter hardiness has limited the distribution and use of buffelgrass Pennisetum ciliare (L.) Link. Efforts to improve winter hardiness have focused on the development of genotypes with rhizomes. The deep placement of rhizomes provides a means of avoiding low temperatures. Rhizomatous cultivars, such as 'Llano' and 'Nueces', are excellent forage types; however, they tend to flower erratically and produce only a limited amount of seed. This drastically reduces the use of these rhizomatous cultivars. The objective of this study was to investigate the effect of temperature and photoperiod on flowering and seed set in buffelgrass. Two different studies were conducted at College Station, TX. The first was a field study in which six genotypes of buffelgrass, three rhizomatous types ('Blue', T-1754, and PI 409164) and three non-rhizomatous types ('Common', 'Formidable', and 'Frio') were planted in a randomized complete block design. A second study was conducted in a growth chamber using the same six genotypes. All genotypes were grown at a constant temperature of 30 C̊ and at three different photoperiods (8, 12, and 16 hr). The parameters measured in both studies were number of days to flowering, number of flowering tillers, seed set, leaf number at flowering, and growing degree days (GDD). Although all six genotypes achieved 100% flowering, the rhizomatous genotypes required more days to achieve flowering and produced more leaves at flowering. The non-rhizomatous genotypes had better seed set than the rhizomatous genotypes. The non-rhizomatous genotypes produced more seed per spikelet than the rhizomatous genotypes. The non-rhizomatous genotype Formidable had more seed per spikelet due to higher fertility. There were differences in flowering in the growth chamber study across all daylengths. Flowering ocurred only at the 12 hr daylength. In conclusion, the non-rhizomatous genotypes had higher seed set, but the rhizomatous genotypes had an acceptable seed set, contrary to past observations. The non-rhizomatous genotype Formidable had the highest fertility, which indicates it could be used as a parent in future breeding programs.