Dinâmica de crescimento e nutrição do capim-marandu submetido a doses de nitrogênio. / Growth dynamic and nutrition of marandu grass grown in nitrogen rates.

AUTOR(ES)

João de Deus Gomes dos Santos Júnior

DATA DE PUBLICAÇÃO

2001

RESUMO

The objective of this research was to examine nutritional and growth attributes of Marandu grass (Brachiaria brizantha cv. Marandu) under nitrogen rates and growth ages. Among the nutrients, nitrogen stand out by its effects in promoting forage yield. The study of growth dynamic and nutrition of Marandu grass is a important tool to promote the production and quality of this forage plant. The experiment was carried out in glasshouse conditions, with nutrient solution using ground quartz as substrate. The experimental design used was a complete randomized block design, with treatments arranged in a 5x6 factorial, with four replications. The Marandu-grass was grown in nitrogen rates of 28, 112, 210, 294 and 378 mg L-1 and it was evaluated at the ages of 21, 28, 35, 42, 49 and 56 days after seedling emergence. The nutrient solution was prepared with a constant NO3-:NH4+ proportion of 70%:30% and was replaced once a week after the first growth age. Nitrogen rates and growth ages interaction was significant (P<0.05) for all nutritional and growth attributes of Marandu-grass, with exception for the mean net assimilation rate and specific root length. The nitrogen rates in each growth age showed significant effects (P<0.05) on the total dry matter yield, roots dry mass, number of tillers, leaf area, root length, root surface area, nitrogen concentration, SPAD value, leaf area ratio and relative growth rate of Marandu grass. Maximum dry matter production was estimated to occur at nitrogen rates between 257 and 304 mg L-1, depending on plant age. The critical nitrogen concentration determined in the most recently expanded leaf lamina was significantly (P<0.01) influenced by plant ages and ranged from 33.8 to 12.8 g kg-1. SPAD values at the critical nitrogen concentration rates were 45.0; 45.7; 49.5; 50.2; 45.7 and 35.3 for growth periods of 21, 28, 35, 42, 49 and 56 days, respectively.

ASSUNTO(S)

growth nitrogen crescimento vegetal fertilizantes nitrogenados capim marandu nutrição vegetal nutrition marandu grass

Documentos Relacionados

• Response of the marandu grass to combinations of nitrogen and sulphur rates.
• Análise de crescimento do capim-marandu submetido a doses de nitrogênio
• Productive, nutritional and metabolic characteristics of marandu palisadegrass grown with nitrogen and magnesium rates
• Crescimento do capim-marandu submetido à estratégias de lotação intermitente
• Produtividade e composição bromatológica do capim-marandu a fontes e doses de nitrogênio