Morphogenesis of Tanzania guinea grass under nitrogen doses and plant densities

Abstract

The objective of this work was to evaluate effects of nitrogen fertilization and plant density on morphogenesis of Tanzania guinea grass. It was used a random block design with 12 treatments and two replications in a 4 × 3 factorial arrangement, with four doses of nitrogen (N) (without N application, 80, 160 or 320 kg/ha.year) and three plant densities (9, 25 or 49 plants/m²). Harvest was performed at 25 cm from the ground when the canopy intercepted 95% of the incident light. Rates of leaf appearance and pseudostem elongation were positively and linearly influenced by nitrogen, whereas phillochron and leaf life span were influenced linearly and negatively. Leaf elongation responded positively to two factors, whereas leaf senescence rate and number of live leaves were not influenced by the factors evaluated. Number of total, basal and aerial tillers were greater at the density of 9 plants/m² and at the nitrogen dose of 320 kg/ha.year. Nitrogen increases production of leaves and tillers in Tanzania guinea grass defoliated at 95% of light interception, but high density of plants reduces the number of tiller per bunch

Adubação Nitrogenada Em Capim-Massai: Morfogênese E Produção

“…Uma série de trabalhos avaliando os efeitos do nitrogênio (N) sobre a taxa de alongamento foliar também mostrou resultados semelhantes (2,(7)(8)(9) . A TAlF é uma medida de grande importância na análise de fluxo de tecidos das plantas e correlaciona-se positivamente com o rendimento forrageiro (Tabela 1), já que, à medida que se aumenta a TAlF, há incremento na proporção de folhas e, consequentemente, maior área foliar fotossinteticamente ativa, promovendo, assim, maior acúmulo de massa seca (2) .…”

“…Ao se considerar que o número de folhas revela o potencial fotossintético da planta, os dados evidenciam que o N pode aumentar o NFV e o CFL incrementando sua capacidade de assimilação de carbono (2,(7)(8)(9) . De fato, observou-se correlação positiva e altamente significativa entre o CFL e a produção de MST, MSF e MSC (Tabela 1).…”

“…É sabido que a água é um dos fatores abióticosEm relação à produção de massa seca, observou-se efeito linear e positivo (P<0,0001) da adubação nitrogenada para MST (Figura 6), MSF (Figura 7) e MSC (Figura 7), não tendo sido observado efeito (P=0,6753) para MSMM (Ŷ = 12,01). O aumento da produção do capim-massai com o incremento das doses de N é explicado pelo fato de o N agir como fator controlador dos diferentes processos de crescimento e desenvolvimento das plantas, proporcionando aumento de biomassa pela fixação de carbono (7,8) . Vários estudos foram conduzidos nesse sentido, em que se observaram aumento significativo na produção de massa seca a medida que se incrementou a adubação nitrogenada (2)(3)(4) .…”

Biomass accumulation in mombasa guineagrass plants under different levels of nitrogen supply and plant densities

“…According to Braz et al (2011), the lack of effect of nitrogen and densities on dead material can be explained by the established strategy of the cuts at 95% light interception. This management aims to increase the rate of liquid accumulation of DM by the maintenance of pasture in critical leaf area index, thus reducing forage losses due to senescence.…”

Partial correlation analysis in the study of morphogenesis and herbage accumulation in Panicum maximum cv. ‘Tanzânia’

“…and management on the response of pairs of traits, and also to identify strategies that can be used to improve simultaneously two variables of interest for the management and production of herbage (MARTUSCELLO et al, 2005;BRAZ et al, 2011;SANTOS et al, 2012). Despite this application, the simple correlation coefficient does not necessarily represent a cause-effect relationship between the traits; i.e., the fact that both increase or are inversely proportional does not mean one trait is affecting another.…”