Comparative responses of fodder and grain teff (Eragrostis tef (Zucc.) Trotter) cultivars to spatial, temporal and nutritional management.
Teff has its origin in Ethiopia as grain crop, while in South Africa it is primarily a forage crop for hay and recently as summer grazing pasture. The response of teff herbage and grain production to planting date, growth stage at cutting, seeding rate and N fertilizer application was studied. Previously limited research data were available for teff production in South Africa. Spring plantings (September to October) are required to maximise total herbage yield with 9.40, 8.48 and 7.64 t DM ha -1) recorded for 1996/97, 1997/98 and 1998/99 respectively. Summer plantings (November to December) give maximum herbage yield from the first cut, yielding 4.42, 4.72 and 3.78 t DM ha -1) for 1996/97, 1997/98 and 1998/99 respectively. The exact planting date is season dependent. Temperature and rainfall determine the beginning of the growth season regarding favourable conditions for teff germination and growth. Herbage yield of cut 1 increases with advancement in growth stage at cutting. Cutting at the vegetative and piping stages gives most number of cuts , up to five yielding 7.45 t DM ha -1) (1996) while the full flowering stage gives the least (one or two cuts , 4.75 and 7.72 t DM ha -1 in 1996 and 1997 respectively). Yield is also affected by environmental conditions influencing germination, biomass accummulation and regrowth after cutting and by lodging. A trade-off results between herbage quantity and quality. Yield increases while quality decreases with advancing phenological stage, resulting in reduced digestibilty and CP and increased fibre content. Seeding rate differences were manifested primarily in weed infestation level, which varied between cultivars depending on leafiness and associated sward density. Nitrogen application levels gave maximum response between 75 and 150 kg N ha -1, with some cultivar differences. Split N application according to expected yield distribution related to planting date is recommended. Grain yield response to seeding rate and N fertilization levels could not be established. Heavy grain losses through thunderstorms and wet conditions at grain maturity precluded yield measurements. Teff yield responses are influenced by day length, environmental factors, such as temperature and rainfall. and phenological stage at cutting. These variables influence biomass accumulation and regrowth.