Effects of severe defoliation on the morphological characteristics of grasses
Main impacts that severe defoliation in pastures can cause |
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- Root Growth: Severe defoliations of grasses can cause a greater reduction in radical growth than moderate defoliations, this is because the distribution of energy resources changes drastically after each severe defoliation, because after the removal of leaf area the photosynthetic activity decreases and the reserves used for root growth are sent are diverted for the growth of the leaf area.
Reduction of leaf area: Defoliation decreases the leaf area, which in turn reduces the photosynthetic capacity of the plant. This directly affects the production of biomass and the accumulation of reserves.
Alteration of vegetative growth: Plants respond to defoliation by activating their meristems (growth zones) to produce new leaves and stems. However, the intensity and frequency of defoliation can affect the growth rate and the distribution of biomass between different parts of the plant. The plants that persist under intensive grazing are those that have the growth points close to the soil surface, which indicates that the cutting height is important to consider at the time of being grazed.
Stem dynamics: Defoliation can reduce or stimulate the production of stems in pastures attributed to different variables such as differences between species, phenological status of the plant, time and intensity of grazing. According to Clavero (1991), I reported that the stress of defoliation increases the proportion of dead stems decreases the ratio of Live/Dead stems, When the apical meristems of a stem are completely removed the stem does not produce new leaves and all new growth depends on a new stem, frequent and intense defoliations remove almost the entire leaf area and retards the production of stems through a reduction in photosynthetic activity.
- Development of reserve structures: To cope with periods of stress, plants can increase the production of storage organs such as rhizomes and stolons, which allows them to survive adverse conditions and quickly regrow after defoliation.
- Rotate grazing: Rotating the animals between different paddocks allows the plants to recover and prevents overgrazing.
- Select adapted grass species: Choosing grass species tolerant to defoliation and with high regrowth capacity is essential to maintain the productivity of grasslands.
Final considerations |
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Bibliographic references |
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- Clavero, T. (1991). Course on production and research in tropical grass. Editorial Agropecuaria "Circulo ganadero de venezuela" Maracaibo: Venezuela.
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