Partial suppression of pampas grass [Cortaderia selloana and C. jubata] by other species at the early seedling stage.
1990
Gadgill R.L. | Sandberg A.M. | Allen P.J. | Gallagher S.S.
Productivity of pampas grass seedlings was studied in the glasshouse in monoculture and in 50% mixtures with seedlings of 14 different species. The growth medium was sand from a pampas-infested forest and observations were made at low, medium and high nutrient status. Six of the species were tested at all three nutrient levels, six at the low level only and one ('Grasslands Paroa' Italian ryegrass) at the two higher levels. Seed of one species (creeping soft-grass) failed to germinate satisfactorily). Pampas growth was suppressed to some extent by all species at the high nutrient level. There was no evidence of suppression by 'Grasslands Maku' lotus, 'Grasslands Kahu' timothy or 'Grasslands Egmont' browntop at the medium nutrient level or by lotus, timothy, sweet vernal grass or 'Massey' creeping bent at the low level. Species showing potential for suppressing pampas were: Italian ryegrass, 'Grasslands Matua' prairie grass, 'Massey Basyn' Yorkshire fog, 'Whittet' Kikuyu grass, 'Grasslands Wana' cocksfoot, 'Grasslands Maru' phalaris, 'Grasslands Egmont' browntop, annual meadow grass, and 'Penncross' creeping bent. Trials designed to investigate the mechanism of suppression on two of the most effective species showed that suppression of pampas caused by prairie grass was not associated with thiram or carboxin used in seed dressings. Seed exudates were not responsible for pampas growth suppression caused by either Italian ryegrass or prairie grass. In a 3-month trial, productivity of pampas grown with Italian ryegrass increased 7-fold when roots of the two species were separated. Root separation in pampas/prairie grass culture caused a 5-fold increase in pampas productivity. Separation of plant tops had no detectable effect on pampas growth.
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