Grass species can be classified into different functional types based on their growth strategies, and contrasting persistence strategies are observed in different grass species. Excluding seedling recruitments, changes in populations of grasses are basically a trade-off between natality and mortality of tillers. We hypothesised that the persistence pathway of perennial grasses is linked to their growth strategy, regardless whether they are growing as monoculture or as a mixture. Species with contrasting growth strategies (Arrhenatherum elatius L., Dactylis glomerata L., and Festuca arundinacea Schreb.) were cultivated as monocultures and as a mixture and their tiller natality and mortality were evaluated for two years after swards establishment. All pastures maintained their population size during the experimental period, although decreases in tiller densities occurred during the warmer season. Arrhenatherum elatius had the highest tiller mortality and natality whereas the F. arundinacea had the lowest ones. Arrhenatherum elatius had many tillers appearing in all seasons but their tillers were short-lived. Conversely, F. arundinacea and D. glomerata developed numerous tillers during autumn and winter and their tillers survived, on average, almost six and three times longer than those of A. elatius, respectively. There were no differences in tillering dynamics among populations grown in monocultures or in the mixture. Regardless of whether they were cultivated in monocultures or as a mixture, the persistence pathway of perennial grasses is linked with their growth strategies with exploitative species presenting a high tiller turnover throughout the year whereas the persistence of more conservative species is based on a high tiller survival.

Resumo -O objetivo deste trabalho foi avaliar o acúmulo de forragem e o valor nutritivo do híbrido de Urochloa 'BRS RB331 Ipyporã' (Urochloa brizantha x Urochloa ruziziensis) submetido à pastejo intermitente. Os tratamentos corresponderam às combinações entre as condições de pré-pastejo, interceptação de 95% da luz incidente e máxima interceptação de luz, e as de pós-pastejo, 10 e 15 cm de altura de resíduo, em delineamento de blocos ao acaso, em arranjo fatorial 2x2, com quatro repetições. Pastos manejados com 95% de interceptação da luz apresentaram maior taxa de acúmulo de forragem, proporção de folhas, relação folha:colmo, teor de proteína bruta e densidade populacional de perfilhos basilares (DPPb), em comparação àqueles manejados com máxima interceptação da luz. Pastos manejados com 15 cm de altura do resíduo apresentaram maior DPPb do que os manejados com 10 cm e apresentaram pequena variação de DPPb entre as estações do ano avaliadas, independentemente do tratamento. Pastos do híbrido interespecífico de Urochloa 'BRS RB331 Ipyporã' apresentam maior acúmulo de forragem e maiores teores de proteína bruta e digestibilidade in vitro da matéria orgânica e menores teores de fibra em detergente neutro na fração folha, quando manejados com 95% de IL nas condições de pré-pastejo, com 30 cm de altura do dossel, associada com 15 cm de altura de resíduo.Termos para indexação: Brachiaria brizantha, Brachiaria ruziziensis, altura do dossel, densidade populacional de perfilhos, híbrido de braquiária, manejo de pastejo. Forage accumulation and nutritive value of the Urochloa interspecific hybrid 'BRS RB331 Ipyporã' under intermittent grazingAbstract -The objective of this work was to evaluate the forage accumulation and nutritional value of the Urochloa hybrid 'BRS RB331 Ipyporã' (Urochloa brizantha x Urochloa ruziziensis) subjected to intermittent grazing. The treatments corresponded to combinations of the pre-grazing conditions, interception of 95% of incident light and maximum light interception, and of the post-grazing heights, 10 and 15 cm, in a randomized complete block design with a 2x2 factorial arrangement and four replicates. Pastures grazed at 95% of light interception showed higher forage accumulation rate, proportion of leaves, leaf:stem ratio, crude protein content, and basal tiller population density (BTPD), in comparison with those managed at maximum light interception. Pastures managed with post-grazing heights of 15 cm showed greater BTPD than those managed at 10 cm and showed a slightly variation in BTPD among the evaluated seasons of the year, regardless of the treatment. Pastures of the interspecific hybrid of Urochloa 'BRS RB331 Ipyporã' show greater forage accumulation and higher crude protein content and in vitro organic matter digestibility, and lower content of neutral detergent fiber in the leaf fraction, when managed with 95% LI under pre-grazing conditions of 30-cm sward height, associated with a post-grazing 15-cm sward height.Index terms: Brachiaria brizantha, Brachiaria ruziziensis, sward...

Core Ideas Mixing grass forage species can increase forage yield and stability. Overyielding was more influenced by increasing leaf biomass rather than stem biomass. Dominant grasses with contrasting growth strategies can compose productive and stable pastures. Mixtures composed of species with different growth strategies (e.g., exploitative and conservative), which have different abilities for resource capture and use, are thought to improve grassland ecosystem services. However, plant species that compete better for limiting resources can become dominant. This study examined whether potential dominant perennial grasses with different growth strategies can compose productive and stable forage mixtures under low competition for resources (nutrients and light). Arrhenatherum elatius L. (exploitative), Festuca arundinacea Schreb. (conservative), and Dactylis glomerata L. (moderately exploitative) were sowed as monocultures and as a three‐species mixture. Pastures were fertilized to maintain high soil fertility levels and mowed by half when their canopies reached 20 cm in height (95% of light interception in the vegetative stage) allowing for over 2 yr of data collection. The proportion of each species in the mixture remained unaltered throughout the experimental period. Transgressive overyielding was not observed; however, the mixture presented a similar yield to the most productive monocultures (10,200 kg DM ha−1 yr−1), although D. glomerata, which presented the lowest yield in monoculture (6400 kg DM ha−1 yr−1), comprised 68.1% of post‐cutting biomass in the mixture. Arrhenatherum elatius and F. arundinacea populations presented less yield variance in monoculture, but higher yield stability was observed in the mixture. Overyielding in the three studied species was strongly affected by leaf production. Mixtures composed of perennial grasses with different growth strategies when grown in nutrient‐rich soil and under conditions of low light competition can compose productive and stable swards, while maximizing leaf production.

White grubs (Cyclocephala flavipennis) damaging perennial winter pastures in the South Region of Brazil.Ciência Rural, v.47, n.5, 2017. In the South Region of Brazil, besides the traditional cultivation of winter-annual pastures, cultivation of winter perennial grasses, particularly tall fescue (Festuca arundinacea Schreb.) and orchardgrass (Dactylis glomerata L.), can be an alternative to reduce the periods of low forage production from native and cultivated perennial warm season grasses. Despite the growing relevance of pasture cultivation in the temperate climate regions, little is known about the soil insects causing pasture damage in these areas. In Brazil, 1,008 species of melolontids (Coleoptera: Melolonthidae) have been reported. The larvae of these species live in the soil, and are commonly called "white grubs" (MORÓN, 2004

The objective of the study was to evaluate the effect of pre‐ and post‐grazing targets on the forage accumulation and canopy characteristics of Marandu palisade grass (Brachiaria brizantha [Hochst. ex A. Rich.] Stapf. syn. Urochloa brizantha) to define grazing management strategies in Brazil's Cerrado biome. The experimental design comprised a randomized complete block with four replicates in a 2 × 2 factorial arrangement of treatments: two grazing frequencies (95% of light interception (LI95%) and maximum (LIMax) light interception of the forage canopy) and two grazing intensities (10 and 15 cm of post‐grazing canopy height). Pastures were sampled to quantify forage mass and morphological components at pre‐ and post‐grazing. The tillers population density and forage nutritive value were estimated at pre‐grazing. Pastures managed with the LI95% target demonstrated greater basal (1,341 versus 1,193 tillers/m2) and aerial tillers (101 versus 53 tillers/m2) population densities, a greater leaf:stem ratio (3.8 versus 2.0), and a lower canopy height (33 versus 55 cm), forage mass (3,225 versus 4,320 kg/ha), stem proportion (30.6% versus 44.5%), and leaf (2.5% versus 2.8%) and stem (3.4% versus 3.8%) acid detergent lignin content than those managed with the LIMax target. In the Cerrado, Marandu palisade grass must be grazed when the canopy height reaches 33 cm. Furthermore, animals must be removed from the paddocks when the canopy height reaches 15 cm.