Leonardo Araripe Crancio

Produção animal em pastagem nativa submetida ao controle de plantas indesejáveis e a intensidades de pastejo

The aim of this experiment was to study different methods of controlling undesirable plants in native pastures, associated with two levels of herbage allowance, and their effects on animal production. The treatments were no control (T), spring slashing (P), spring+autumn slashing (P+O) and spring slashing +chemical control (P+Q), under two levels of herbage allowance (8 and 14kg of dry matter 100kg -1 of liveweight per day). The experimental design was a randomized complete block with two replicates. Not have block effects neither interaction between methods of control and herbage allowances (P>0.05). The higher herbage allowance resulted in more liveweight gain per area (P 0.05). The results showed that it’s possible to keep the live body weight of bovine in native pasture in Serra do Sudeste of Rio Grande do Sul/ Brazil, during the winter ’s period, utilizing management practices that secured a minimals levels of herbage allowance. These results showed also that the management of native pasture with slashing in spring, with or without chemical’s controlling, it’s provide a better individual development and less weight’s lose in winter’s period.

Produção de forragem e dinâmica de uma pastagem natural submetida a diferentes métodos de controle de espécies indesejáveis e à adubação

It was tested the effects, in a medium term, of four methods to control undesirable plants on forage production and dynamic of vegetation in a representative area of natural pasture in the transition between Serra do Sudeste and the Depressao Central in Rio Grande do Sul. The control methods were the following: without control, mechanical control with spring mowing, mechanical control with autumn mowing and chemical control with Tordon commercial herbicide based on Picloram + 2,4-D at the dosage 5 L/ha associated or not with the fertilization system (with and without fertilizer). There was an interaction between fertilization system and season of the year and interaction between the control method and season of the year for available forage and grass mass. The fertilization system improved the available forage [4,919.0 kg/ha of dry matter (DM)] and mass of grasses (2,313.1 kg/ha of DM). Forage mass was higher in the absence of undesirable plant control, which resulted in values 5,024.4, 3,931.3, 3,020.1 and 3,701.1 kg/ha of DM in the summer, winter, autumn and spring, respectively. The frequency of undesirable species is not modified by fertilization (8.0% without fertilizer and 8.4% with fertilizer). Chemical control promotes total control of undesirable species and native leguminous. Autumn mowing is more efficient in controlling undesirable species than spring mowing.

Ganho de peso de novilhas em pastagem nativa da Serra do Sudeste do RS submetida ao controle de plantas indesejáveis e intensidades de pastejo

This work aimed to evaluate the effect of different undesirable plants controlling methods and grazing intensities on animal production in native pastures. The treatments were no control (T), spring clipping (P), autumn clipping (O) and chemical control (Q), under two levels of forage allowance, medium (8%) and high (14%), expressed in kg of dry matter offered daily per each 100kg of liveweight. The experimental design was a completely randomized block arranged in a factorial with two repetitions. Statistical analysis showed no interaction among treatments nor differences among control methods for variables concerning primary and secondary production (P>0.1). Animal performance in both forage allowances was not different (P>0.1). High forage allowances increased animal performance per unit area (P<0.1).

Herança do peso de grãos primários e secundários de aveia

The development of varieties with high grain physical quality, yield and adaptation is one of the main objectives of the oat breeding programs in the South of Brazil. Grain weight is one of the criteria used to determine oat quality and, in order to define the best strategies for the improvement of this trait, it is important to study its genetic basis. Until now, studies of this nature have not been conducted with the Brazilian oat genotypes. This work was carried out with the objective of studying the inheritance of primary and secondary oat grain weight. Samples of 20 primary and secondary grains of a variable number of plants from the generations P1, P2, F1, F2 and F3 from five crosses were weighted. From these data, frequency distributions, variances and the predominant gene effects were obtained and heritability values were estimated in the broad sense and using the parent-offspring regression. The results showed that there is variability in early generations for the weight of primary and secondary grains and that additive and dominance are the main acting gene effects. The presence of major genes was not detected in the expression of these traits. Continuous variation in the F2 generation and low to moderate heritabilities indicate that low selection pressures are recommended in early generations.