Growth, nutrition and production of dry matter of Kikuyu Grass (Brachiaria humidicula) as a function of Mn-fertilizer

Abstract

Manganese (Mn) is important to increase forage crop yields. However, there is little information regarding the adequate Mn-fertilizer rates for Brachiaria humidicula species. The objective of this research was to evaluate the effect of manganese on growth, nutrition and yield of Brachiaria humidicula. The study was carried out in a green house in a randomized block design with five rates of manganese (0, 15, 30, 60 and 120 mg dm -3 ) and four replicates. Were evaluated plant height, leaf area, relative chlorophyll index, dry matter production, manganese accumulation and content, besides absorption efficiencies and transport and use of manganese (Mn). Brachiaria humidicula showed high tolerance to this nutrient, because the application of only 120 mg dm -3 to the soil was phytotoxic, showing symptoms such as brown spots and leaf tip curling. Manganese applied at a dose of 120 mg dm -3 reduced aerial part biomass yield by 25% and promoted lower efficiency of use of this nutrient by the forage by 49%. However, even with the initial content of manganese in the soil considered sufficient to meet nutritional demands to achieving high yields, the application of 60 mg dm -3 of manganese to the soil is recommended.

Manganese accumulation and dry matter production of Guinea Grass (Panicum maximum) after application of increasing doses of Mn fertilizer

“…These results are similar to those observed by Arruda et al, (2016), who showed higher concentrations of Mn 2+ in Urochloa humidicula at the second cut. They attributed this increase in Mn 2+ concentration to the greater root development compared with the first cut, which favored the nutrient absorption (Arruda et al, 2016). Guirra et al (2011) and Sylvestre et al (2012) observed the same pattern when assessing the effect of Mn in Tanzania grass (Panicum maximum) and Urochloa brizantha cv.…”

“…The absorption efficiency of Mn (AB ef ) did not differ among the evaluated Mn rates. In Urochloa humidicola Arruda et al, (2016) observed an enhanced AB ef with the increase of Mn doses. Since this nutrient is toxic when its level is high in soil, these results suggested that Guinea Grass may is less susceptible to the toxic stress by Mn than Urochloa humidicola.…”

“…Some authors suggest that nitrogenous ammonia-based fertilizations may condition soil pH reductions (Ducic and Polle, 2005), as a result of the ammonium transformation process in nitrate (Cantarella et al, 2007), and consequently, increasing the availability of Mn 2+ in the solution (Smith and Paterson, 1990;Freitas et al, 2007). This process may explain the Mn 2+ increase in the shoot from the first to the second cut (Sylvestre et al, 2012;Arruda et al, 2016), whereas spaced fertilizations of urea were conducted using rates of 100 mg dm -3 of N at sowing and 50 mg dm -3 30 days after.…”

“…The increases observed in shoot, root and whole plant dry matter production are attributed to increased photosynthetic rate, due to the necessary Mn absorption for the metabolic functions of plant (Schmidt et al, 2013;Arruda et al, 2016). However, the excess of exchangeable Mn in the soil promotes biochemical disturbances that can reduce the plant biomass production (Papadakis et al, 2007;Millaleo et al, 2010;Millaleo et al, 2013), as observed at the highest rates applied.…”

“…Plant species with nutrient deficiency have reduced root growth (Prado, 2008) and, consequently, lower crop yields. On the other hand, in high concentrations it may be toxic (Doyle et al, 2003), conditioning morphological (Arruda et al, 2016. ) and biochemical disorders in vegetables (Lidon et al, 2004;Millaleo et al, 2010;Marschner, 2012;Millaleo et al, 2013), and in forages, can trigger animal poisoning after ingestion (Prado, 2008).…”