The Paspalum genus includes several species that are important for livestock in Rio Grande do Sul, such as P. notatum and P. guenoarum, typical of native pastures of the Pampa biome. The aim of this study was to investigate forage production and chemical composition of four ecotypes of these species in relation to the cv. 'Pensacola' (P. notatum). Ecotypes of P. guenoarum (Azulão and Baio) and P. notatum (André da Rocha and Bagual) and the cv. 'Pensacola' were evaluated for two years, during which four cuts/year were made. The work was carried out under field conditions at the Agronomic Experimental Station of the Federal University of Rio Grande do Sul (30°05'S; 51°39'W), in a completely randomized design. P. guenoarum stood out for higher productivity and greater tolerance to cold; the Azulão ecotype showed more autumn production in relation to the other ecotypes. Crude protein content ranged from 14 (Baio) to 15% ('Pensacola'); for neutral detergent fiber, the variation was 68 (Azulão) to 71% ('Pensacola') and for acid detergent fiber there was a variation of 38 ('Pensacola') to 43% (Baio). The data demonstrates the potential of native genotypes for use as cattle feeding in southern Brazil.

-This study assessed the effect of successive applications of pig slurry on the dry matter (DM) production and the nitrogen use efficiency of giant missionary grass along two years. A total of 55, 110, 165, 220 and 275 m 3 of pig slurry/ha/year were applied in order to supply 100, 200, 300, 400 and 500 kg of total N/ha/year, respectively. These treatments were compared with the ammonium nitrate (200 kg of N/ha/year) source of N and with a control (no nitrogen application).Annually, nitrogen was applied in four divided doses, after the cutting of forage grasses, which takes place five times a year.The total DM yield did not differ between years and increased linearly as a function of pig slurry application, ranging from 2,698 kg of DM/ha/year (control) to 11,371 kg of DM/ha/year (275 m The efficiency index of pig slurry ranged from 0.52 to 0.72.

Eragrostis plana (Nees) is an allelopathic plant with invasive potential in South American pastures. To isolate and identify phytotoxic compounds from leaves and roots of E. plana, a bioassay-directed isolation of the bioactive constituents was performed. This is the first report on a new diterpene carbon skeleton, neocassane, and of three new neocassane diterpenes, neocassa-1,12(13),15-triene-3,14-dione, 1; 19-norneocassa-1,12(13),15-triene-3,14-dione, 2; and 14-hydroxyneocassa-1,12(17),15-triene-3-one, 3, identified from the roots. Compounds 1, 2, and 3 inhibited the growth of duckweed by 50% at concentrations of 109 ± 28, 200 ± 37, and 59 ± 15 μM, respectively. Compound 2 was fungicidal to Colletotrichum fragariae, Colletotrichum acutatum, and Colletotrichum gloeosporioides. The compounds identified here could explain the allelopathy of E. plana. The description of the newly discovered compounds, besides contributing to the chemical characterization of the species, may be the first step in the study of the potential of these compounds as bioherbicides.

Allelopathy is an important ecological mechanism in natural and managed ecosystems. Its study is critical to understand natural plant behaviors, to isolate allelochemicals with herbicide potential, and to use the allelopathic genes in transgenic studies. Poaceae is an ecologically dominant plant family and it is economically important worldwide because its chemical diversity represents an important source to discover new molecules. From this viewpoint, Brazil is an interesting place to study, encompassing 197 genera of the Poaceae family, many of them being dominant in various biomes and some being native to Brazil. Here, we review the literature describing allelopathic activities involving grasses of the Poaceae family. We evaluate the experimental conditions used in these studies, we identify the allelochemicals involved, and, finally, we assess the applicability of allelopathy. Our main findings are (1) among the 47 Brazilian species studied for their allelopathic effects, only Bothriochloa barbinodis, Bothriochloa laguroides, Paspalum notatum, and Paspalum urvillei are native to Brazil; (2) 51% of the reviewed studies prepared extracts from the leaves and used lettuce as the target plant; and (3) 64% of the papers identified allelochemicals, of which 67% were phenolic acids. This first bibliographical survey on allelopathy in Poaceae species present in Brazil shows that less than 3% of the Brazilian species have been studied, suggesting it is an incipient research subject. Since this plant family is a valuable source of unknown natural products, refining such studies should contribute to a better understanding of the ecosystem relationships. Identification and isolation of grass allelochemicals should promote environmentally safer compounds with bioherbicide properties, in sustainable agriculture. Keywords Allelochemicals. Bioprospecting. Grasses. Native resources Contents 1. Introduction 2. Poaceae genera native to Brazil with allelopathic effect 3. Experimental conditions 3.1 Plant organs used to prepare extracts 3.2 Target species 3.3 Evaluation of allelopathic effect 4. Allelochemicals in Poaceae genera native to Brazil 5. Allelopathy and its applicability 6. Conclusion References

-This study was carried out to investigate the effect of extracts of leaf and roots of tough lovegrass (Eragrostis plana) on seedling growth of white clover (Trifolium repens), in two experiments. The first experiment was conducted as a pilot test, in which two concentrations (30 and 60%) of leaf aqueous extract were tested. In Experiment II, source (leaf/root) and concentration (5 and 10%) of the extracts were combined. Distilled water was used as control in both trials. Fifty seedlings at 7 days of age were placed in gerbox containers on filter paper moistened with extracts and incubated at 25°C for 14 days. In the first experiment, percentage of normal seedlings decreased by 82.5% and 100% at the concentrations of 30% and 60%, respectively, which indicated the need to increase the dilution of the extracts. In the subsequent experiment, the extracts from the two sources, at 10% of concentration, reduced by 78% the percentage of normal seedling and increased the percentage of abnormal seedlings, which reached 27%. At 5% concentration, the leaf extract was the most deleterious treatment, resulting in greater mortality (M=27.6%) and abnormality (A=19.5%) of seedlings, compared to the root extract (M=4.8%; A=9.5%) and the control (M=2.4%; A=0.25%). The morphological changes caused by the extracts were radicle necrosis, retention of cotyledons and absence of secondary roots. The results suggest that allelopathic compounds from leaves and roots of tough lovegrass differ in chemical nature and/or concentration.Key Words: allelophaty, abnormal seedlings, dead seedlings Crescimento de plântulas de trevo-branco tratadas com extratos aquosos de folha e raiz de capim-annoni-2 RESUMO -Este estudo foi realizado para investigar o efeito do extrato de folhas e raízes de capim-annoni-2 (Eragrostis plana) no crescimento de plântulas de trevo-branco (Trifolium repens), em dois experimentos. O primeiro experimento foi conduzido como teste-piloto, no qual foram testadas duas concentrações (30% e 60%) de extrato aquoso de folhas. No experimento II houve uma combinação de fonte (folhas e raízes) e concentração (5% e 10%) dos extratos. Água destilada foi utilizada como testemunha em ambos os ensaios. Cinqüenta plântulas com sete dias de idade foram colocadas em caixas gerbox, sobre papel-filtro umedecido com os extratos, e incubadas a 25ºC durante 14 dias. No primeiro experimento, o percentual de plântulas normais decresceu em 82,5% e 100% nas concentrações de 30% e 60%, respectivamente, o que indicou a necessidade de se aumentar a diluição dos extratos. No experimento subseqüente, os extratos das duas origens, a 10% de concentração, reduziram em 78% o percentual de plântulas normais e aumentaram o percentual de plântulas anormais, que atingiu 27%. A 5% o extrato de folha foi o tratamento mais deletério, resultando em maior mortalidade (M=27,6%) e anormalidade (A=19,5%) de plântulas, comparado ao de raiz (M=4,8%; A=9,5%) e à testemunha (M=2,4%; A=0,25%). As alterações morfológicas causadas pelos extratos foram necrose da rad...

-This study was conducted in order to verify if the phenological stage and the nitrogen fertilization interfere in the allelopathic activity and in the concentration of potentially allelopathic phenolic compounds of tough lovegrass (Eragrostis plana). The assay consisted of a bifactor 3 (0.100 and 200 kg N ha -1 ) x 2 (harvested in vegetative and reproductive stages), in a split plot design. The N doses constituted the main plot and the phenological stage during the harvest the subplots, resulting in six treatments. The tough lovegrass plants derived from each of the treatments were subjected to allelopathy bioassays, in which aqueous extracts of the aerial parts were applied to lettuce cypselae (Lactuca sativa) and to phytochemicals tests when ethanolic extracts were used, with subsequent partition with ethyl acetate, followed by a high-performance liquid chromatography analysis. There was nitrogen x phenological stage interaction on biological and chemical attributes. The allelopathic extracts were, in descending order of inhibition of germination, those from plants harvested at the vegetative stage and fertilized with 100 kg N and at the flowering stage with 200 kg N, which showed the highest catechin concentrations. The caffeic, ferulic, p-coumaric and vanillic acids were in a higher concentration in flowered and fertilized plants with 0 or 200 kg N. The management of the nitrogen fertilization and the harvesting age influence the allelopathic activity and the phytochemical composition of tough lovegrass.Keywords: germinability, phenolic acids, catechin, epicatechin. RESUMO -Este estudo foi realizado com o objetivo de verificar se a fenologia e a adubação nitrogenada interferem na atividade alelopática e na composição fenólica do capim-annoni (Eragrostis plana

Diversos cultivares de Cynodon dactylon têm sido cultivados no Rio Grande do Sul para alimentação do rebanho leiteiro, na forma de pastejo ou feno. A rápida determinação do valor nutritivo dessas forrageiras pode ser útil para seu manejo e para o planejamento da dieta dos animais. Este trabalho teve como objetivo desenvolver curvas de calibração para análise do valor nutritivo de quatro cultivares de Cynodon (Tifton 68, Tifton 85, Florakirk, Coastcross), utilizando o método de reflectância no infravermelho proximal (NIRS). Foram utilizadas 129 amostras de forragem verde, coletadas e analisadas entre 1998 e 2001. Os coeficientes de determinação para proteína bruta, fibra insolúvel em detergente neutro, fibra insolúvel em detergente ácido, matéria seca, cálcio, fósforo, potássio e magnésio foram, respectivamente: 0,98; 0,97; 0,99; 1; 0,92; 0,97; 0,99 e 0,72%. Os erros-padrão de calibração foram de 0,38; 0,60; 0,35; 0,14; 0,02; 0,01; 0,05 e 0,01%, respectivamente. As equações obtidas foram consideradas de excelente resolução para todos os parâmetros estimados, o que indica a acurácia do método para a espécie avaliada.

RESUMO -Este trabalho foi conduzido com o de objetivo avaliar o desenvolvimento morfológico de Paspalum dilatatum Poir. biótipo Virasoro, tendo como testemunha para tolerância ao frio a festuca (Festuca arundinacea Schreb.), espécie hibernal e exótica. Foram realizadas doze colheitas da parte aérea (dezembro/00 a novembro/01), de plantas cultivadas no campo. O virasoro caracterizou-se pela arquitetura caulinar, florescimento precoce e longo, estabilização do afilhamento no outono e inverno, com retomada do crescimento a partir da primavera. A festuca apresentou arquitetura foliar, florescimento tardio e curto e afilhamento constante. Ambas são cespitosas e rizomatosas; a touceira do virasoro é aberta no centro, onde o material morto se deposita, enquanto a festuca tem touceira fechada, com deposição do material morto ao redor das plantas. O virasoro alocou maior quantidade proporcional de biomassa em inflorescências e colmos em relação à festuca. Esse biótipo é tipicamente estival, com excelente tolerância à geada, vegetando vigorosamente com o aumento das temperaturas. Palavras-chave: fenologia, hábitoMorphophysiological and Agronomic Characterization of Paspalum dilatatum Poir. Biotype Virasoro and Festuca arundinacea Schreb. 1. Morphological Development ABSTRACT -This work had the objective to evaluate the morphological development of the Paspalum dilatatum Poir. biotype Virasoro, having as witness the tall fescue (Festuca arundinacea Schreb.), winter and exotic species. The shoots were harvested for twelve times (December/00 to November/01) from the plants cultivated in the field. The virasoro was characterized for its stem architecture, early and long flowering, and for the stabilization of the tillering during autumn and winter, with accentuated increase of this process in the spring. The tall fescue showed foliar architecture, late and short flowering and constant tillering. Both of them are caespitose and rhizomatous plant; the plant of virasoro is open in the middle, where the dead material is located, whereas the tall fescue is closed with the dead material located around the plant. The virasoro allocated more proportional quantity of biomass in the inflorescences and culms comparing to the tall fescue. This biotype is typically warmer, but with excellent tolerance to frost and vegetating strongly with the increase of the temperatures.