Growth and productive responses of tropical grass Panicum maximum to nitrate and ammonium supply

Abstract

This study was conducted to investigate growth response parameters and forage yield of Panicum maximum Jacq. plants supplied with nitrate (NO 3-) and ammonium (NH 4 +) as N source in a nutrient solution. Six NO 3 and NH 4 + combinations were tested at the following proportions: 100-0, 85-15, 70-30, 55-45, 40-60 and 25-75%. Grass shoot (number of tillers and leaves and leaf surface area) and root (length and surface area) growth parameters and dry matter production exhibited highest values in P. maximum plants growing in the nutrient solution supplied with NO 3-:NH 4 + at the proportions ranging between approximately 70-30 and 55-45%. The use of NO 3-:NH 4 + mixture at the ratio of 55-45% instead of the NO 3 solely as N source in the nutrient solution enhanced the production of tillers and leaves and the leaf area surface of P. maximum by about 30, 20 and 30%, respectively. Plants supplied with NO 3 and NH 4 + mixture (55-45%) showed an increased root length and root surface area by approximately two and six-fold, respectively, compared with P. maximum fertilized with NO 3 exclusively in the growth medium. Supplying N in the nutrient solution as NO 3 or NH 4 + exceeding approximately 70 or 50%, respectively, caused a diminished P. maximum forage yield. Enhanced N-use efficiency associated with P. maximum plants supplied with a NO 3 and NH 4 + mixture in the growth medium supports the assumption that it is possible to increase plant production by managing N fertilization based on quality (N forms) of N fertilizers applied in pasture systems.

Nitrogen recovery, use efficiency, dry matter yield, and chemical composition of palisade grass fertilized with nitrogen sources in the Cerrado biome

“…Palisade grass supplied with urea, urea with urease inhibitor, and polymer-coated urea showed better NUE than ammonium sulfate-nitrate in the fourth growth period (Table 1) and by the end of the study (Table 2). This result is possibly associated with the increase of N-NH 4 + uptake rather than N-NO 3 by plants fertilized with urea, urea and urease inhibitor, and polymer-coated urea, since the relationship between these ions changes the DMY (Masclaux-Daubresse et al, 2010;Santos et al, 2013). In the soil, urea is hydrolyzed by the urease enzyme, resulting in the formation of ammonium carbonate, which rapidly decomposes yielding N-NH 4 + , which is taken up and assimilated without energy expenditure (Rochette et al, 2009;Taiz and Zeiger, 2009).…”

“…Additionally, the constant technological innovation in the manufacturing process of N fertilizers interferes with the available form of N in the soil solution and with processes related to N losses, such as volatilization of ammonia (N-NH 3 ), among other factors (Cantarella et al, 2008;Sanz-Cobena et al, 2008). These changes in the amount of N available in the system and in the ratio of nitrate (N-NO 3 -) to ammonium (N-NH 4 + ) in the soil solution affects the recovery of applied nitrogen (RAN), nitrogen use efficiency (NUE), dry matter yield (DMY), and the chemical composition of pastures (Peyraud and Astigarraga, 1998;Primavesi et al, 2005;Santos et al, 2013;Silveira et al, 2013). Thus, some studies have been and are being conducted to evaluate the effect of N fertilizers on the above-mentioned parameters (Gilbert et al, 1958;Kresge and Younts, 1962;Martha Junior et al, 2004Primavesi et al, 2004Primavesi et al, , 2005Costa et al, 2008Costa et al, , 2009Costa et al, , 2010Silva et al, 2011Silva et al, , 2013Silveira et al, 2007Silveira et al, , 2013.…”

Biological Nitrification Inhibition (BNI): Phenotyping of a Core Germplasm Collection of the Tropical Forage Grass Megathyrsus maximus Under Greenhouse Conditions

“…A second hypothesis is that there is substantial intraspecific variation in the preference of M. maximus to different forms of mineral N, so that germplasm accessions that exhibited high NR may have a stronger preference to assimilate NO 3 − without altering its biomass production. Previous studies explored the performance of different genotypes of M. maximus in nutrient solutions under different levels of NH 4 + : NO 3 − , finding that growth is optimal when both sources are present in a similar proportion (Andrade et al, 2001a,b;Santos et al, 2013). Santos et al (2013) reported that shoot growth parameters of the cv.…”

“…Previous studies explored the performance of different genotypes of M. maximus in nutrient solutions under different levels of NH 4 + : NO 3 − , finding that growth is optimal when both sources are present in a similar proportion (Andrade et al, 2001a,b;Santos et al, 2013). Santos et al (2013) reported that shoot growth parameters of the cv. Aruana diminished when NH 4 + exceeded 60% of the N in nutrient solution and was less affected to the excess of NO 3 − .…”

Análises fisiológicas e bioquímicas da forrageira tropical Panicum maximum Jacq. (Poaceae) cultivada em elevado CO₂ atmosférico e aquecimento

“…As pastagens abrangem cerca de 70% da área agrícola do mundo (Soussana e Lüscher, 2007) e constituem uma das fontes de alimentos mais importantes para a atividade pecuária (Santos et al, 2013). No Brasil, as áreas de pastagens ocupavam, até 2006, 172 milhões de hectares, o que representa 20% de todo o território nacional (IBGE, 2006) e Panicum maximum Jacq.…”