Evaluation of the physiological potential of Panicum maximum seeds by multivariate analysis

The aim of this work was to identify efficient vigor tests for differentiating the seed lots, forecasting seedling emergence in the field and assessing the physiological quality of Panicum maximum seeds. 12 seed lots from the cultivar Tanzania and 11 seed lots from the cultivar Massai were evaluated for water content, germination, first count and germination speed index, emergence and first emergence count of seedlings in sand, root length and shoot length, analysis of SVIS® images (seedling length, vigor and uniformity index) and seedling emergence in the field. The work was conducted in a completely randomized design for tests performed in the laboratory and in randomized blocks for tests in the field. The data were subjected to analysis of variance and the means compared by Scott Knott's test at 5% probability and statistical multivariate clustering analysis and principal components analysis. The shoot and root length tests are efficient for the evaluation of the physiological potential of P. maximum cv. Massai, while the seedling length, vigor index and growth uniformity index tests using image analysis, seedling emergence in sand and first seedling emergence count in sand are efficient in assessing the physiological potential of seeds of P. maximum cv. Tanzania, and providing information similar to that of seedling emergence in the field.

Características produtivas, agronômicas e nutricionais do capim-tanzânia em cinco diferentes idades ao corte / Productivity, agronomical and nutritional traits of Tanzânia grass cut on five different ages

Avaliou-se o capim-tanzânia (Panicum maximum cv Tanzânia) cortado aos 42, 63, 84, 107 e 126 dias quanto à produtividade, às características agronômicas, à composição bromatológica e à digestibilidade in vitro. Observou-se aumento na altura da planta do capim-tanzânia até os 84 dias, com aumento da produção de massa verde de forragem e aumento na produção de matéria seca com o avançar da idade ao corte. O aumento da idade ao corte resultou em diminuição do percentual de folhas e em aumento no percentual de hastes. Na composição bromatológica, observaram-se diminuição do teor de proteína bruta e aumento das frações fibrosas, com aumento do nitrogênio retido nessa última com o avançar da idade. Os resultados obtidos refletiram-se na cinética de fermentação ruminal, descrita pela técnica in vitro semiautomática de produção de gases, demonstrando menor potencial de produção de gases, menor taxa fraccional de fermentação e, consequentemente, menor degradabilidade efetiva da matéria seca. Recomenda-se o corte do capim-tanzânia no intervalo de 42 a 63 dias de crescimento.

The potential for use of Tanzania grass (Panicum maximum cv. Tanzania) cut at different ages for the production of silage was evaluated. In the first experiment, Tanzania grass, cut at 42, 63, 84, 107, and 126 days of growth, was evaluated considering its productivity, agronomic characteristics and chemical composition. It was observed gain in height of Tanzania grass until the 84th day, with increased the production of green fodder and mass production of dry material with the advancing age of cutting. It also resulted in a decrease in the percentage of leaves and an increase in the percentage of stems. Regarding chemical composition, it was detected a decrease in crude protein percentage and an increase of fibrous fractions with the advancing of age. The results were reflected in the kinetics of rumen fermentation of Tanzania grass cut on the 42nd, 63rd, 84th, 107th, and 126th days, described by semi-automated in vitro gas production technique, showing less potential for gas production, lower fractional of fermentation and, consequently, less effective degradability of dry matter. For the production of grass silage, it is recommended cutting the Tanzania grass from 42 to 63 days of age.

Atributos do solo sob pastagens em sistema de sequeiro e irrigado / Soil attributes under pasture system with and without irrigation

A pecuária é uma das atividades econômicas mais importantes da região do cerrado, sendo que o sucesso dessa atividade é dependente do sistema de manejo e de gramíneas forrageiras adaptadas às condições edafoclimáticas da região. Objetivou-se, neste tabalho, avaliar os atributos do solo em áreas sob pastagens com capim-Tanzânia (Panicum maximum Jacq. cv. Tanzânia) e braquiarão [Brachiaria brizantha (Hochst ex A. Rich.) Stapf. cv. Marandu], em sistema de sequeiro e irrigado no município de Rio Verde, GO. O experimento foi instalado no Centro Tecnológico Comigo, em um Latossolo Vermelho-Amarelo Distrófico típico, em 16 parcelas com 450m² cada. Adotou-se o delineamento em blocos completamente casualisados, referindo-se aos quatro tratamentos: capim-Tanzânia e braquiarão com e sem irrigação, com quatro repetições. Foram realizadas análises de atributos físicos (estabilidade de agregados) e químicas (pH, cálcio, magnésio, potássio, fósforo, acidez potencial, capacidade de troca catiônica, saturação por bases e conteúdo de matéria orgânica). Os atributos químicos variaram em ambas as profundidades, decorrentes principalmente da ação da calagem e adubação do solo independente da ausência ou presença de irrigação. Os tratamentos com capim-Tanzânia e braquiarão sem irrigação apresentaram os maiores teores de matéria orgânica e tiveram os maiores valores do diâmetro médio geométrico (DMG). A maior porcentagem dos agregados ficou retida na peneira de > 2,0mm de malha. A irrigação não afetou a produção de massa seca do capim-Tanzânia e braquiarão.

The livestock production is one of the most important economic activities in the Brazilian savanna and its success depends on the management system used as well as the use of grasses adapted to the edaphoclimatic conditions of the region. Therefore, the aim of this work was to evaluate the soil attributes under pasture with Tanzania grass (Panicum maximum Jacq. cv. Tanzania) and bread grass [Brachiaria brizantha (Hochst ex A. Rich.) Stapf. cv. Marandu], with and without irrigation, in the municipality of Rio Verde, Goiás State, Brazil. The experiment was carried out on an oxisol soil at the Comigo Technological Center, in 16 plots of 450m² each. The experimental design used was the completely randomized blocks with four replications. The treatments consisted of two grass species, Tanzania grass (Panicum maximum) and bread grass (Brachiaria brizantha) and two irrigation treatments, with and without irrigation. The following attributes were determined: aggregate stability, pH, calcium, magnesium, potassium, phosphorus, potential acidity, cation exchange capacity, base saturation, and organic matter content. The chemical attributes varied in both layers mainly due to the liming and fertilization of the soil, independently of the irrigation system. The treatments with Tanzania grass and bread grass without irrigation presented the highest organic matter content and the highest values of DMG. Most of the aggregates had a diameter larger than 2.0 mm. The irrigation management did not affect the dry mass of the grasses studied.