Morphogenetic and structural characteristics of signal grass in response to liming and defoliation severity

Abstract

The control of soil acidity through liming and the adoption of adequate management are essential to the maintenance of pastures productivity. The morphogenetic and structural characteristics of Urochloa decumbens cv. Basilisk, in canopies with (0.7 t ha-1 and 1.0 t ha-1) or without liming and subjected to severe or lenient cuttings (stubble corresponding to 40 % or 60 % of the pre-harvest height, respectively), were evaluated throughout regrowth, during late spring and summer. Treatments were distributed in a 3 x 2 factorial arrangement, in a completely randomized block design, with 3 replications (80 m2 plots). Increased liming rates do not result in benefits to the herbage mass, tiller population density or a faster canopy recovering. The average tiller weight decreases, while the duration of regrowth linearly increases, with increasing liming rates, particularly in late spring. Stem elongation and leaf senescence rates increase and leaf elongation rates decrease from the 15th day of regrowth, regardless of the liming rates or defoliation severities. Post-harvest heights ranging from 40 % to 60 % of the pre-harvest height showed to be within the tolerance limits to defoliation of U. decumbens. The liming rates adopted had only marginal impacts on the morphogenetic characteristics of U. decumbens.

Characterization of Brachiaria decumbens ‘Basilisk’ pasture subjected to flexible grazing by sheep

“…With the increase in regrowth age, plants tend to decrease the L/S ratio, reflecting in the leaf weight ratio (LWR), which tends to follow the same response. Some studies (Rozalino Santos et al, 2014;Pereira et al, 2018) showed that when approaching the critical LAI, the tillers of 'Basilisk', direct part of the carbohydrates produced in the leaf fraction, to the supporting organs (such as the stem), resulting in a production of this at the expense of that.…”

“…With the increase in the resting period, the canopy tends to increase support materials (rich in lignin) at its base, whose main function is to support the weight of the canopy. According to Pereira et al (2018), B. decumbens grass tends to start its stem deposition way before the critical LAI, with the beginning of the stem elongation rate and deposition of this fraction starting from the 15 th day of the rest period.…”

“…Of all the species of this genus, the most grown cultivar throughout the national territory is Basilisk, popularly known as brachiarinha. Its rapid diffusion and acceptability were mainly due to its high adaptability to acid soils, resistance to grazing, good DM yield (kg ha -1 ) (Pereira et al, 2018), and its growth habit (decumbent) that guarantees good soil coverage (Rozalino Santos et al, 2014).…”

Impactos Técnico-Econômicos Da Adubação De Pastos

“…Sabe-se que a calagem de manutenção não resulta em aumento instantâneo na massa de forragem, pois observa-se impacto na produtividade a partir do quarto ano após a aplicação do calcário (PRIMAVESI et al, 2004b;PEREIRA et al, 2018). Entretanto, estes resultados tardios ocorrem diante de sistemas que utilizam baixas quantidades de fertilizantes ou em solos que já estão com a saturação de bases exigida pela cultura (PRIMAVESI et al, 2004b;PEREIRA et al, 2018). Por isso, diante de sistemas mais intensivos, com maior uso de fertilizantes, a calagem proporciona resultados mais imediatos, pois esta prática aumenta a CTC do solo, o que diminui os riscos de fixação de fósforo e de lixiviação de nitrogênio e potássio.…”

Mowing and lowering the marandu palisadegrass sward height at late winter improve the sward structure

“…Sward structure is defined as the arrangement and spatial distribution of parts of above ground plant within their community (PEREIRA et al, 2010), which influences in the light interception and, in effect, the photosynthesis of forage canopy (PEDREIRA;PEDREIRA, 2007;PERI et al, 2003). In addition, the sward structure changes the microclimate inside the canopy and has consequence on the tillering dynamic (COSTA et al, 2016;PESSOA et al, 2016) and on the growth of the individual tiller (PAULA et al, 2012;PEREIRA et al, 2018). Regarding the animal, the sward structure is important because it determines the degree of ease on which the forage is digested during grazing and, consequently, influences the animal performance (CARVALHO et al, 2015).…”