Dynamic of dominance, growth and bromatology of Eragrostis plana Nees in secondary vegetation area 1 Dinâmica da dominância, crescimento e bromatologia de Eragrostis plana Nees em área de vegetação secundária

ABSTRACT -The objective of this work was to evaluate the dominance, growth and bromatology of tough lovegrass or 'annoni' grass (Eragrostis plana) in secondary vegetation area. The evaluations were carried out at 23, 45, 64, 86, 111, 132, 153, and 174 days of growth after a mowing. The tough lovegrass was the dominant species on the area, accounting for 76 to 90% of biomass. There was a linear increase for leaf (9.8 kg DM ha -1 day -1 ) and total dry mass (16.9 kg DM ha -1 day -1 ) of the tough lovegrass. During the 111 days of the vegetative stage, the biomass was composed only of leaves, and the flowering started at 132 days. At 174 days, the tough lovegrass accumulated about 4,000 kg DM ha -1 , 650 kg DM ha -1 of which was composed of inflorescences. The growth analysis revealed a specific leaf area of 72 cm 2 g -1 and a maximum leaf area index of 2.1. The leaf area ratio decreased from 72.2 to 43.9 cm² g -1 between the 23 rd and 174 th days. The bromatological analysis showed a high content of neutral detergent fiber (85.3-90.4%) and acid detergent fiber (39.4-42.8%), as well as low crude protein content (3.9-9.9%), indicating the low forage quality of the species. entre o 23º e o 174º dia após o corte. A análise bromatológica mostrou elevados teores de fibra em detergente neutro (85,3-90,4%) e fibra em detergente ácido (39,4-42,8%), e baixo teor de proteína bruta (3,9-9,9%), indicando a baixa qualidade nutricional do capim-annoni. Palavras-chave: Fibra. Índice de área foliar. Massa seca. Proteína bruta. Razão de área foliar

Biomass allocation and morphophysiological correlations in forage legumes with contrating growth habits

The biomass allocation analysis and the correlation among morphophysiological variables allow greater understanding of the establishment, yield and persistence of perennial species in plant breeding projects, management and ecology of forage plants. To analyze the biomass allocation of forage legumes (Adesmia latifolia, A. punctata, A. tristis, Lotus corniculatus, L. uliginosus), an experiment was carried out under greenhouse conditions for 210 days (4000 degree-days); the plants were cultivated in 1 m² wooden boxes. Plants were harvested to evaluate the morphological components and to describe their growth habit. The root, stem and leaf biomass allocations were expressed as dry mass percentages. The greatest allocation on leaves occurred for stoloniferous species, A. latifolia (63.5%) and A. punctata (61.4%), which presented the smallest allocation for roots, 10.9 and 14.7%, respectively. Largest stem biomass allocation (39.4%) and roots (24.4%) were found for L. uliginosus, a species with rhizomes. The leaf area index (LAI) was positively correlated with the number of leaves, secondary stems and aerial biomass. A. latifolia and Lotus spp. are extreme examples of the relative importance of morphological components in the formation of LAI and biomass. The accumulation pattern and forage allocation of stoloniferous legumes are mainly characterized by leaf production, pointing out the importance of stolon elongation and rooting, while for A. tristis and Lotus spp., the stem and root fractions had the same importance.A análise da alocação da biomassa e a correlação entre variáveis morfofisiológicas permitem maior entendimento do estabelecimento, produção e persistência de espécies perenes, em trabalhos de melhoramento genético, manejo e ecologia de plantas forrageiras. Este trabalho teve o objetivo de analisar a alocação de biomassa em leguminosas forrageiras (Adesmia latifolia, A. punctata, A. tristis, Lotus corniculatus, L. uliginosus). O experimento foi conduzido em casa de vegetação durante 210 dias (4000 graus-dia); as plantas foram cultivadas em caixas de 1 m². Nesse período, foram retiradas amostras periódicas para avaliação dos componentes morfológicos e descrição do hábito das espécies. A alocação da biomassa em raízes, caule e folha foi expressa em percentagem de massa seca. A maior alocação em folhas ocorreu nas espécies estoloníferas, A. latifolia (63,53%) e A. punctata (61,42%), que, por sua vez, mostraram a menor alocação em raízes, 10,90 a 14,77 %, respectivamente. Maior alocação de biomassa em caule (39,38%) e raízes (24,39%) foi verificada em L. uliginosus, espécie rizomatosa. Para todas as espécies, o índice de área foliar (IAF) esteve correlacionado positivamente com número de folhas das hastes secundárias e biomassa aérea. A. latifolia e Lotus spp. são exemplos extremos da relativa importância dos componentes morfológicos na formação do IAF e da biomassa. O padrão de acúmulo e alocação de biomassa nas leguminosas estoloníferas é caracterizado, principalmente, pela produção de folhas, indicando a importância do alongamento e enraizamento dos estolões, enquanto em A. tristis e Lotus spp., as frações caule e raízes apresentam igual importância

Forage potential of native ecotypes of Paspalum notatum and P. guenoarum

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