Morphogenesis of native grasses of Pampa Biome under nitrogen fertilization

Abstract

-Morphogenetic and structural characteristics of the native grasses of the Pampa Biome Andropogon lateralis, Aristida laevis, Axonopus affinis, Erianthus angustifolius, Paspalum notatum, Paspalum plicatulum, Piptochaetium montevidense and Sorghastrum pellitum were evaluated as to the effect of nitrogen (N) fertilization (zero and 100 kg N/ha). The experimental design was of randomized blocks with three replicates in a 8 × 2 (native grasses × N) factorial arrangement. Accumulated thermal sums of 350 and 700 degree days determined the interval between cuts for prostrate and caespitose growth habit species, respectively. Species considered of resource conservation (A. laevis, E. angustifolius, P. plicatulum and S. pellitum) had the highest leaf elongation rate when they received N. For leaf appearance rate, phyllochron, leaf senescence rate, leaf lifespan, number of green leaves and final length of leaf blades, there was difference between the evaluated species.

Tifton 85 grass responses to different nitrogen levels and cutting intervals

“…LAR was higher (p < 0.05) in the 1st and 4th cut at the 28-d interval and there was no difference in the 2nd and 3rd cuts (Table 1). N application did not influence LAR (p > 0.05; LAR is the average number of leaves that appeared per tiller per day or degree days (PEREIRA et al, 2011;MACHADO et al, 2013). LAR was higher (p < 0.05) in the 1st and 4th cut at the 28-d interval and there was no difference in the 2nd and 3rd cuts (Table 1).…”

“…However, Pereira et al (2011) reported that LAR in Tifton 85 grass increased from 0.0024 and 0.0023 leaves per tiller per day for each increase of 1 kg of N applied in the first and second year, respectively. N is required for cell division and elongation in the tiller meristematic zone and therefore, in most cases, LAR increases with increasing N. Phy is the time interval between the appearance of two successive leaves and is the inverse of LAR (PACIULLO et al, 2005;PEREIRA et al, 2011;MACHADO et al, 2013). Phy was higher (p < 0.05) for the 35-d interval in the 1st, 2nd, and 4th cuts, and there was no difference in the 3rd cut compared to 28 d interval (Table 1).…”

Beef heifers grazing behavior and herbage intake in natural grassland under rotational grazing

“…Rest period between occupations of the 375 DD is based on the time (in degrees-sum) for elongation of 2.5 leaves per tiller of functional types A and B (EGGERS et al, 2004). The 750 DD rest interval is based on the time for elongation of 1.5 leaves per tiller of functional types C and D (MACHADO et al, 2013). The experimental units of the 375 DD had seven subdivisions and the 750 DD treatments had eight subdivisions.…”

“…Due to this high complexity, management of these grasslands becomes a challenge. In this way, to simplify its management, grass species were grouped according to morphogenetic characteristics and classified into four functional groups (EGGERS et al, 2004;CRUZ et al, 2010;MACHADO et al, 2013). Using grass species traits, QUADROS et al (2009) proposed life elongation duration as a determinant time (in degrees days sum) in order to quantify the rest intervals between grazing for benefit specific different groups of plants.…”

Morphogenesis of the giant missionary grass in response to pig slurry fertilization

“…Massai, an almost 122% increase in LER was verifi ed at a dose of 1,200kg N ha -1 (LOPES et al, 2013). MACHADO et al (2013) observed an increase in LER near 46% in Paspalum plicatulum after the application of 100kg N ha -1 , but no effect was verifi ed on A. affi nis. The LER values obtained here (0.55 to 1.03mm tiller -1 DD -1 ) were higher than those that BANDINELLI et al (2003) found for Andropogon lateralis in response to N application up to 400kg N ha -1 year -1 (0.449 to 0.659mm tiller -1 DD -1 ).…”