Ontogênese foliar de Typha domingensis Pers. sob influência do fósforo

Abstract

The Cattail (Typha domingensis) is a macrophyte which in eutrophication conditions may have a high growth and colonization capacity. Therefore, the aim was to evaluate the leaf ontogeny and meristem structure and activity in T. domingensis species in the presence of phosphorus. Plants were collected from natural populations in Alfenas-MG region, and grown in greenhouse in order to obtain clones for the experiment. Clone rhizomes were selected and cultivated in nutritive solution with different phosphorus concentrations. Leaves and bracts were collected and subject to usual procedures in plant microtechnique. Leaf primordia formation occurs laterally to the shoot apical meristem, and its formation and growth continue due the leaf apical meristem, marginal meristem, laminar meristem and intercalary meristem. Leaf tissue differentiation occurs in basipetal sense, except for the vascular and support tissues which development shows acropetal sense. Differences were observed in all the quantitative characteristics. The phosphorus enhanced ground meristem and procambial proportions, cell production rate in the primary meristems, aerenchyma proportion, average area of aerenchyma chambers but reduced the cell cycle time in ground meristem. Furthermore, this element reduced the time for palisade parenchyma and aerenchyma development. The leaf formation pattern in cattail, which shares features with other monocot species, and the differences promoted by phosphorus, may be related to morphological, physiological and ecological characteristics.