Defoliation patterns and tillering dynamics in Italian ryegrass under different herbage allowances
This work was carried out in order to generate information on the tillering process and to contribute for the understanding of the defoliation process on Italian ryegrass (Lolium multiflorum Lam.) grazed by lambs under different herbage allowances: 6, 8 and 12 kg of dry matter per 100 kg of animal live weight per day. The grazing method was intermittent. The experimental design was completely randomized following a repeated measure arrangement, with three treatments and two area replications. The intensity of defoliation is greater at 6 and 9% herbage allowances. The defoliation interval is higher at 12% herbage allowance, intermediate at 9% and lower at 6%. The rates of tiller emergence, survival and death, stability index the tiller population are similar for the different herbage allowances and differ according to the phenological stage of ryegrass. Structural changes caused by canopy management with low herbage allowance and/or due to the advance in developmental stage of ryegrass alter defoliation strategies, with more intense and frequent grazing.
Nitrogênio e saturação por bases no desempenho do capim-pojuca (Paspalum atratum Swalen cv. Pojuca) cultivado em vasos
This work aimed to evaluate the growth and dry matter production of Pojuca grass grown in haplic Gleysol. The experiment was carried out in greenhouse of the Soil Science Department of the Universidade Federal de Lavras, Lavras, MG, Brazil. The sowing of seeds was performed in plastic pots without holes, with a capacity of 4 dm3 each of soil. The treatments consisted of four doses of N (0, 100, 200 and 400 mg/dm3) and four levels of base saturation (40, 50, 60 and 80%). The experimental design was in a randomized complete blocks, making up a 4 x 4 factorial scheme with four replicates. Three cuts at the height of 4 cm from soil level were proceed. Previous for the first cut, the tiller appearance rate (TAR), tiller elongation rate (TER) and leaf appearance rate (LAR) were studied. Also, dry matter (DM) yield and tiller density (TD) were assessed. The N doses increased (P 0.05) was observed for LAR. Nitrogen fertilization provided increases in TD and DM yield of Pojuca grass. No significant response was observed for increased levels of base saturation of the soil for the studied variables. It was concluded that application of N is indispensable for a good growth and good DM production of the Pojuca grass, being not needed to raise the base saturation level of the soil above 40% in haplic Gleysol.
SOME EFFECTS OF DROUGHT ON PERENNIAL RYEGRASS SWARDS
Herbage production and tiller dynamics were measured in “Grasslands Nui” perennial ryegrass (Lolium perenne L.) swards for 3 months during summer, under conditions of either irrigation or water stress. Measurements continued through winter and early spring when both treatments were well supplied with water. At the end of the stress period tiller densities were 11000 and 4000 tillers/m* in the irrigated and the stressed plots respectively. Lack of moisture stopped tiller emergence but had little effect on the relative death rate of tillers formed before water stress. During the stress period, herbage production was greater in the irrigated than in the stressed plots, average accumulation rates of 68 and 21 kg DM/ ha/dav respectively being recorded. After re-watering, there was compensatory growth by the previously stressed swards resulting in a higher accumulation rate, the average accumulation rates were 24 and 15 kg DM/ha/dav for the previously stressed and irrigated plots respectively. The higher accumulation rate was due mainly to a greater rate of tillering in the previously stressed plots. Differences between treatments in herbage production and tillering were significant up to 3 months after rewatering. The results are discussed in relation to pasture management.