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Revista Brasileira de Zootecnia

versão impressa ISSN 1516-3598versão On-line ISSN 1806-9290

Resumo

GOMIDE, Carlos Augusto de Miranda; GOMIDE, José Alberto; MARTINEZ Y HUAMAN, Carlos Alberto  e  PACIULLO, Domingos Sávio Campos. Photosynthesis, organic reserves and regrowth of mombaçagrass (Panicum maximum Jacq.) under different defoliation intensities of the main tiller. R. Bras. Zootec. [online]. 2002, vol.31, n.6, pp.2165-2175. ISSN 1516-3598.  https://doi.org/10.1590/S1516-35982002000900003.

An experiment was carried out to evaluate morphophysiological aspects of Mombaçagrass growth after defoliation. Defoliation treatments were performed when the number of green completely expanded leaves on main tiller had stabilized around 3. Four defoliation treatments were imposed to the main tiller: T1 - no defoliation, T2 - total defoliation, T3 - removal of the last expanded leaf and T4 - removal of the two lowest expanded leaves. In all cases primary tillers were completely defoliated by cutting at 8 cm height from soil level. The variables assessed were: leaf expansion rate, root growth, relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR) at the ages of 2, 5, 9 and 16 days regrowth, stem and root total non structural carbohydrate content and maximum leaf photosynthesis rate at the ages of 2, 6 and 13 days regrowth. There were five replications, according to a completely randomized design. There was no difference in the photosynthetic rate among the 3 expanded leaves considered at defoliation time. Photosynthetic rate of any leaf remaining after defoliation increased initially, but had declined by the 13th day of regrowth. Stem total non-structural carbohydrates content dropped in response to leaf removal, mainly in the total defoliation treatment which also brought about reduced root growth. Still, the completely defoliated plants had restored their RGR by the 16th day regrowth due to high leaf area expansion rate and leaf area ratio.

Palavras-chave : assimilate partitioning; carbon balance; growth rate; leaf area; respiration; reserves.

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