Título en español.

Abstract

The productivity of Napier, Guinea, Para, Pangola, and molasses grasses, as affected by nitrogen fertilization and season of the year under both cutting and simulated grazing management, were determined under conditions typical of the humid mountain region of Puerto Rico. Molasses grass yielded much less than the others, all of which were very similar in yield, response to nitrogen fertilization, and seasonal growth rates with both harvest procedures, except that Guinea grass outyielded the others with grazing management. With cutting management and 400 pounds of nitrogen per acre yearly, Napier, Guinea, Para, and Pangola grasses yielded about 24,000 pounds of dry matter per acre yearly having about 8 percent of protein. Yields were lower with grazing than with cutting management. Season of the year markedly affected growth of all grasses with lowest yields occurring from December through March. Seasonal variations were accentuated by nitrogen fertilization. Annual yields of the Para, Guinea, Napier, and Pangola grasses increased rapidly with nitrogen rates up to 400 pounds. However, response was generally limited to the 200-pound rate during seasons of slow growth, but was strong up to at least the 400-pound rate at other times. Molasses grass responded only to the application of 200 pounds of nitrogen per acre yearly at all seasons. Protein content of all the grasses was similar, increased with nitrogen rates, was higher during seasons of slow growth, and lower with cutting than with simulated grazing management. Napier grass had the lowest drymatter content, while Guinea grass had a markedly higher calcium and magnesium content than the others. Otherwise, the forages were very similar in mineral and lignin content. There was little difference in efficiency of nitrogen utilization by the highest yielding grasses. Efficiency was lower with grazing management, higher during seasons of fast growth, and decreased with increasing nitrogen rates

Potential food uses for protein from tropical and subtropical plant leaves

“…Tropical forage grasses photosynthesize more efficiently, grow during most of the year, show excellent regeneration after repetitive cuttings, and with increased nitrogen fertilization respond with increased green forage and protein yields. Extensive investigations on tropical grasses by Caro-Costas et al (1960, 1961, Vicente-Chandler et al (1959, 1961, and Sotomayor-Rios et al (1973,1974,1976) have considerably broadened our understanding of the effects of fertilization and repetitive cuttings on green forage, dry matter, and protein yields.…”

Níveis de nitrogênio e proporções de nitrato e amônio afetando produção, atividade da redutase do nitrato e composição de três gramíneas forrageiras

“…foi obteve maiores produções que as demais forrageiras (P <0.05) e o nível 210 mg.r 1 de N0-3 foi superior ao nível intermediário, o qual superou o menor nível . Houve efeito para a interação de espécies com os níveis de nitrato para o capim-Tanzânia-1 sendo superior aos demais no maior nível de nitrato, evidenciando a alta capacidade de crescimento, taxa de elongação e senescência deste material genético (CARO-COSTAS et al, 1960), quando comparado a outras gramíneas, como demonstrou EMBRAP A ( 1985).…”

“…--0,80 Obteve-se efeito para o fator espécie, evidenciado pela média de cada planta, com diferença (P < 0,05) entre os capins Tanzânia-1 e gordura, que foram iguais ao capim-Marandu. Esses resultados confirmam as produções de matéria seca apresentadas por estas forrageiras, em diversos trabalhos envolvendo comparação entre espécies (CARO-COSTAS et al, 1960;OLSEN, 1972;PEDREIRA, 1973;PEDREIRA & MATTOS, 1981;.…”

“…O capim-Tanzânia-1 reduziu a produção de raízes (P < 0,05), à medida que aumentou a participação de amônio na solução, exceto para a proporção em ausência de cálcio, o que difere do resultado obtido por MONTEIRO et al (1994). Os valores de concentração de nitrogênio na parte aérea (Tabela 9) são relativamente baixos se comparados com os obtidos na literatura (CARO COSTAS et al, 1960, COWARD-LORD et al, 1974FRANÇA & HAAG, 1985;CARVALHO & SARAIVA, 1987;BRUNET et al, 1988a;BOTREL et al 1990e MONTEIRO et al, 1994 Não houve diferença significativa (P > 0,05) na concentração de nitrogênio das folhas velhas (Tabela 11) entre os valores médios de cada espécie.…”