Author
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Gates, Roger |
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Dewald, Chester |
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Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/3/1998 Publication Date: N/A Citation: N/A Interpretive Summary: Pensacola bahiagrass, covering 5 million acres, is one of the most resilient pasture grasses used in the Southeast and also benefits subsequent crops by reducing nematode or soil-borne diseases when used in rotation. Slow establishment is the primary limitation to using bahiagrass for rotations or pastures. Tifton 9, a selection from Pensacola, has higher yield potential, but similarly slow establishment. The seed coat has been implicated as the primary cause of slow germination although in previous field research accelerated aging and solid matrix priming seed treatments did not improve bahiagrass establishment. A pneumatic dehulling device has been used to remove the seed coat of eastern gamma grass without reducing seed viability. We were curious whether the same device could be used to dehull bahiagrass and whether it might improve emergence and establishment. Greenhouse experiments confirmed that dehulled seed did emerge more rapidly, although 28 days after planting differences were small. Field plantings made for 2 yr at a droughty upland site and a lowland site using early Mar through June planting dates revealed no advantage for dehulled seed at the end of the planting year. In uncertain environments where bahiagrass is most often useful, delayed germination of intact seed ensures eventual stand establishment. Technical Abstract: Tifton 9 stands, like other bahiagrasses (Paspalum notatum Fl¿gge var. saurae Parodi) develop slowly. Emergence 7 d after greenhouse planting of Tifton 9 seed dehulled with a pneumatic device (18.3%) was greater (P < 0.01) than untreated seed (0.7%). Twenty-eight d after planting they were not different (36.2%). Untreated (11.2 kg ha-1) or dehulled seed (7.8 kg ha-1) were planted at equivalent rates in 5 blocks of a RCBD on 7 biweekly planting dates from 09 Mar through 01 Jun in 1994 and 1995 at both a droughty upland and a lowland site near Tifton, GA (31 26' N, 83 35' W). Mean surface (0-50mm) soil moisture content at the lowland site (58 g kg-1) was higher than the upland site (28 g kg-1). Seedling heights, measured in June 1994, seedling counts in spring of both yr and 1995 fall plant counts tended to be higher with earlier planting date. No differences in final stand (% occurrence) could be attributed to planting date. Final stand ratings were greater (P<0.05) at the lowland (84%) than at the upland site (79%) and greater (P<0.05) for untreated than dehulled seed in 1994, but no differences were observed in 1995. Development of Tifton 9 bahiagrass stands at these coastal plain sites, was slow, but relatively insensitive to differences in spring or early summer planting date. Dehulled seed emerged more rapidly, but this provided no sustained advantage in stand establishment in these environments. |
