Fatores que afetam as características morfogênicas e estruturais de plantas forrageiras

Abstract

Objetivou-se com esta revisão abordar os principais fatores que afetam as características morfogênicas e estruturais de plantas forrageiras. Dentro do sistema agropecuário brasileiro, predomina-se a criação de animais a pasto. Devido às condições favoráveis do território nacional, é possível produzir diversas espécies de plantas forrageiras. Neste sentido, o entendimento do comportamento do ecossistema de forragem frente às variações dos recursos naturais se torna uma ferramenta capaz de auxiliar na elaboração de metas de manejo sustentáveis. A morfogênese é utilizada para mensurar o aparecimento e expansão dos órgãos vegetais através do fluxo de tecidos que ocorrem dentro do dossel forrageiro. De maneira geral, as características estruturais de um dossel forrageiro dependem das características morfogênicas da espécie, que são determinadas geneticamente. No entanto, essas caraterísticas sofrem influência direta de fatores abióticos e bióticos que alteram o padrão de crescimento dessas plantas. Ademais, através da avaliação dos processos morfogenéticos envolvidos no ecossistema de pastagem, é possível elaborar metas de manejo sustentável do dossel forrageiro, contribuindo para elevar a produtividade dos sistemas agropecuários do Brasil.

Forage productivity and chemical composition of Panicum maximum cv. Mombaça under defoliations intensities and frequencies

“…In conditions of high forage supply, efficiency of the grazing process may be limit by the difficulty of apprehension of leaf blades. Since the increase in time per bit was proportionally greater than the increase in the bite mass, the total forage mass consumed and the ingestion rate stabilized at the highest heights of the pasture (Barbosa et al, 2007;Cruz et al, 2021). The physical limitations imposed by the canopy structure led to lower efficiency forage capture by the animals at the highest heights of the canopy.…”

Evaluation of Natural Regrowth of Axonopus aureus under rest periods in Roraima´s Savannas

“…The values of this work, in all rest periods, were lower than those reported by Costa et al (2008), evaluating A. aureus, under different grazing frequencies, who estimated mean values of 0.101 leaves tiller -1 day -1 ; 2.11 cm day -1 tiller -1 and 0.59 m 2 m -2 , for plants at 45 days of regrowth. Cruz et al (2021) reported an inverse relationship between appearance and expansion of leaves, as the greater the speed of appearance of leaves, the shorter the period available for their expansion. The LER has a high correlation with GDM grass production and has been use as a criterion for grass selection in genetic improvement works, as it is directly relate to the final leaf length, as smaller leaves are usually associated with higher LAR values (Nabinger & Carvalho, 2009;Pereira, 2013;Martuscello et al, 2019;Costa et al, 2021).…”

Forage productivity and morphogenesis of Mesosetum chaseae under defoliation frequency

“…The growth stage at which the plants are harvest directly affects yield, regrowth capacity and persistence. In general, less frequent grazing provides higher forage yields, however, concomitantly, there are sharp decreases in its chemical composition, increase in fiber contents, reductions in the leaf/stem ratio and, consequently, lower consumption by animals (Pereira et al, 2018;Cruz et al, 2021).…”

“…During the vegetative growth stages, the morphogenesis of a grass can be explained by three physiological mechanisms: the appearance rate, the elongation rate and the longevity of the leaves, which are generally genetically determined, however they can be strongly affected by the environmental factors and pasture management practices adopted (Nabinger & Carvalho, 2009;Cruz et al, 2021). The knowledge of the morphogenetic and structural characteristics can allow the proposition of specific management practices for each forage grass (Heringer & Jacques, 2012;Costa et al, 2018) as it provides a visualization of the seasonal forage production curve and an estimate of its quality.…”