Abstract
The objective of this study was to assess the agronomic, morphogenic and structural characteristics of tropical forage grasses during the establishment phase and throughout the second year in northeast Brazil. The treatments included 9 grasses: Brachiaria humidicola (koronivia grass), Brachiaria hybrid cv. Mulato, Brachiaria brizantha cvv. Piata, Xaraes and Marandu, Brachiaria ruziziensis (ruzi grass), Brachiaria decumbens (signal grass), Panicum hybrid cv. Massai and Andropogon gayanus (gamba grass). The grasses were planted in a randomized complete block design with 4 replications. The following parameters were measured: total forage production, leaf:stem ratio, tiller population density, number of dead tillers, leaf emergence rate, phyllochron, leaf elongation rate, stem elongation rate, rate of leaf senescence, final length of leaf blade and life-span of leaves. In the establishment year, cv. Mulato produced the highest forage yields, followed by cvv. Xaraes and Massai, with gamba grass and koronivia grass worst. In the second year, cvv. Mulato, Xaraes and Marandu, and gamba grass showed highest forage production, while cvv. Massai and Piata produced the least. All grasses showed a marked drop in production during the dry season. Cultivar Massai consistently had the highest leaf:stem ratio. The morphogenic and structural characteristics differed according to cultivar and season of the year. In general, leaf emergence rate, leaf elongation rate, stem elongation rate, rate of leaf senescence, final length of the leaf blade, number of live leaves per tiller and density of living tillers were higher in the rainy season, while the phyllochron and life-span of leaves were higher in the dry season. The results of this research highlight the potential of the Brachiaria cultivars Mulato and Xaraes, gamba grass and Panicum cv. Massai in subhumid Maranhao, northeast Brazil.
Highlights
Brazil has an area of more than 220 Mha of pastures, and at least 100 Mha of these are sown pastures (IBGE 2004)
In 2010, when the data were collected during the dry season, average temperature varied from 27.0 °C (July) to 29.0 °C (December)
Forage production, leaf: stem ratio, tiller population density and number of dead tillers differed among the grasses (Table 1)
Summary
Brazil has an area of more than 220 Mha of pastures, and at least 100 Mha of these are sown pastures (IBGE 2004). Sown pasture grasses in Brazil differ in growth rate, nutrient requirements and sensitivity to water stress. Brachiaria spp. are the most commonly used grasses in Brazilian pastures (Macedo 2005), and it is estimated that in the mid-western region of Brazil, 50% of sown pastures are B. brizantha cv. Cultivar Piatã has the advantage of promoting slightly higher animal performance in the dry season. These cultivars, released by EMBRAPA (Brazilian Agricultural Research Corporation), flower at different seasons of the year This difference favors the strategic use of these grasses, taking advantage of the higher nutritional value and productivity of each cultivar in different periods
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