Guilherme Portes Silva

Características morfogênicas e estruturais de perfilhos de capim-braquiária em locais do pasto com alturas variáveis

The objective of this experiment was to evaluate the influence of natural variation of heights of plants on the same pasture on the morphogenic and structural characteristics of Brachiaria decumbens cv. Basilisk managed under continuous stocking with cattle. Four plant heights (10, 20, 30 and 40 cm) were evaluated on the same pasture managed at an average height of 25 cm. It was used a randomized block design with two replications. Leaf appearance rate of signalgrass was linearly and negatively influenced by heights of the plants on the same pasture. The tillers on the same sites with the highest heights showed greater phyllochron (9.3 days). The higher plant heights on the same pasture promoted both higher leaf senescence and pseudoculm elongation rates for the tillers. Leaf lifespan (37.8 days) and leaf elongation rate (1.3 cm/tillers.day) were not influenced by the plant height. The number of green (4.36) and dead (2.15) leaves was not changed by the plants height either. However, the higher height of plants resulted in a linear increase of 69% on the number of leaves showing defoliation. Pseudoculm and leaf blade lengths responded linearly and positively to the increase in the plants height on the same pasture. The natural height variance of plants found on the same pasture changes the morphogenetic and structural characteristics of signalgrass. There is spatial variability of the vegetation on Brachiaria decumbens cv. Basilisk pastures managed under continuous stocking with bovine.

Structure of signal grass pasture with height variation

This study was carried out aiming to evaluate the structural characteristics of Brachiaria decumbens cv. Basilisk pasture. Four heights of plants (10, 20, 30 and 40 cm) were evaluated within the same grazing area in a randomized block experimental design with two repetitions. Variation in the initial height of the signal grass pasture plant showed a linear and a negative response. The masses of green leaf blade mass, live stem, dead material, live forage and total forage linearly increased with heights of the plants on the pasture. However, it was observed a linear reduction in green leaf blade/live stem ratio and the height of the plants on the pasture (from 1.16 to 0.58). Plant height on the pasture had a stronger effect on the increase of live stem and the dead material masses than it had on the green leaf blade mass. Volumetric density of green leaf blade decreased (from 97.09 to 39.07 kg/cm ha DM) with plant height on the pasture. The same response was found for volumetric densities of live forage (from 181.62 to 107.85 kg/cm.ha dry matter) and total forage (from 283.39 to 195.72 kg/cm.ha dry matter). On the other hand, the plant heights on pasture did not affect volumetric density of live stem and dead material, which showed mean values 80.95 and 95.61 kg/cm.ha DM, respectively. The heights of the plants on pasture had a quadratic effect on light interception by the canopy. Grazing areas with heights of 10, 20, 30 and 40 cm showed light interception values of 56.15, 85.16, 93.39 and 96.57%, respectively. It occurs and temporal variabilities on the B. decumbens pasture structure managed under continuous stocking.

Influência da localização das fezes nas características morfogênicas e estruturais e no acúmulo de forragem em pastos de capim-braquiária

The objective of this study is to evaluate morphogenetic and structural characteristics as well as forage accumulation on Brachiaria decumbens pastures according to the site of cattle feces. It was evaluated two grazing areas: near and far from the droppings. The design used was a random block design, with three replicates. Tillers were tagged on the pasture for evaluation of length of the leaves and stems. Leaf appearance and death were also recorded. Stem elongation rate was 80% higher and leaf elongation rate was 23% higher for the tillers near the dropping areas. Phyllochron was also higher for tillers (8.5 days) in sites close to the feces in comparison to those from the distant areas (7.7 days). There was no effect of dropping localization on leaf senescence rate (0.39 cm/tiller.day) and leaf life span (38 days). Final leaf blade length was 25% higher for tillers near the droppings. The number of defoliating leaves (1.3 leaf) was lower in areas near the droppings, contrary to the number of dead leaves (2.8 leaves). Pseudostem length increased 73% as it was closer to the droppings. Number of dead and total vegetative tiller was higher in areas far from the droppings. Higher total growth rate of B. decumbens also occurred in sites close to the droppings. Cattle droppings change the morphogenetic characteristics and structure of B. decumbens pasture. In areas close to the feces, the tissue flow is more intense and forage accumulation is higher.

Grazing patterns on signalgrass pasture according to location of cattle feces

This study was conducted to evaluate the defoliation patterns on B. decumbens cv. Basilisk (signalgrass) tiller as a function of influence of feces deposited naturally by cattle. The signalgrass was managed with an average height of 25 cm, under continuous stocking and variable stocking rate. Interval and intensity of defoliation, grazing efficiency and forage loss were evaluated in two sites on pasture - one close and the other distant from feces. The completely randomized block design with three replications was adopted. The defoliation rate of the pasture site close to feces was 40% lower than at that distant from feces. This response pattern was similar to defoliation intensity of leaf blade. The leaf blade of the tiller close to feces also achieved lower de foliation (1.64) than that in the tiller distant from feces (3.97). The relative number of grazed leaf per tiller in the tillers distant from feces was approximately 185% higher than those close to feces. The grazing efficiency was lower in the local close to feces compared with that distant, unlike forage loss. The natural deposition of feces by cattle modifies the grazing and use patterns of B. decumbens under continuous stocking.