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.
Fluxo de biomassa em pastagem de azevém anual (Lolium multiflorum Lam.) manejada em diferentes alturas
In an italian ryegrass pasture under continuous stocking with sheep, biomass flows were estimated from 2 to 20 October 1999. Treatments corresponded to four different sward heights (5, 10, 15 and 20 cm) maintained by variable stocking. The experimental design was the randomized complete block design with three replicates. The fluxes were defined by morphogenetic and structural variables obtained from measurements performed on marked tillers. During the period in which the intended sward heights were established, significant effects in sward structure resulted in alterations on the biomass fluxes. The growth and intake fluxes showed a quadratic response with maximum values between 10 and 15 cm grazing heights, while the senescence flux increased linearly with sward height. Maximum daily live weight gain and animal yield per hectare were obtained within this interval, indicating this interval being the most appropriate to pasture management. The evaluation period was coincident with the floral induction phase, so the leaf lamina mass was progressively smaller and biomass fluxes showed a negative balance for all treatments.
Secoiridoids from Olea europaea
Abstract Three new secoiridoids have been isolated from the leaves of Olea europaea along with the previously reported. The compounds were identified by spectral means.