Resumo

MEDINA, María G et al. Morpho-structural variables and biomass quality of Tithonia diversifolia at initial stage of growth. Zootecnia Trop. [online]. 2009, vol.27, n.2, pp.121-134. ISSN 0798-7269.

An experiment was carried out with the purpose of evaluating the effect of longitude (10, 20, 30, and 40 cm), diameter (1.0-1.9, 2.0-2.9, 3.0-3.9, and 4.0-4.9), and bud number (2, 3, 4, and 5) of Tithonia diversifolia stakes in some morpho-structural and biomass quality indicators during the initial stage of growth. The measured variables in nursery conditions were differential plant height, regrowth number, branch number, branch longitude, branch diameter, leaves per branch, survival, growth rate, and plagues and illnesses incidence. The biomass nutritional profiles were determinated in terms of its chemical composition (crude protein (CP), true protein (TP), soluble protein (SP), neutral detergent fiber (NDF), CP-NDF, acid detergent fiber (ADF), phosphorus (P), total soluble carbohydrates (TSCH), starch, and ashes), secondary metabolites level (phenols, sterols, terpens, coumarins, and lactonic compounds), and ruminal degradability of dry matter and CP (DMD, CPD). Significant interaction (P<0.05) stake longitude x diameter x bud number in height, and longitude x bud number in branch longitude were observed (P<0,05). Statistical differences in regrowth number, growth rate, and TSCH concentration were observed. The rest of variables did not present significant fluctuation (P>0.05). Under experimental conditions, it is recommended to use stakes of 30 or 40 cm of longitude with 1,0-4,9 cm of diameter with 5 buds, which guarantee a foliage with a good chemical composition (CP: 20.37-23.65%; Ashes: 7.38-8.82%), and ruminal degradability (DMD: 68.93-73.44%; CPD: 72.63-76.94%), but with significant level of sterols (2.49-2.92%), terpens (1.03-1.39%), and lactones (0.30-0.48%).

Palavras-chave : Tithonia diversifolia; nursery; stakes; chemical composition; secondary metabolites; terpens; sterols; lactones.

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