Comparação ecofisiológica e de atributos de crescimento das herbáceas aquáticas Montrichardia linifera (Arruda) Schott e M. arborescens (l.) Schott em tipologias alagáveis contrastantes na Amazônia central

Abstract

The flood pulse of Amazonian rivers imposes on organisms that inhabit the floodplains, the alternation between a water phase and a terrestrial phase. In response to periodic flooding, plants have developed adaptations and specific growth patterns. Montrichardia arborescens (L.) Schott is an aquatic herb occurring in nutrient-poor floodplain (igapós), while Montrichardia linifera (Arruda) Schott occurs in nutrient-rich- floodplain (várzeas). This study aimed to compare the two species over a hydrological cycle, the growth rates, density of stems, biomass, phenology, and chlorophyll content. It was measure the macronutrient (Ma) and micronutrients (Mi) of the species in aquatic and terrestrial phases. The study was conducted in Curari, in the Solimões River (S 03 ° 17'38, 5 "W 059 ° 55'47, 9"), and Praia Grande on the Rio Negro (03 ° 02'18 S, 9 "; W 060 ° 32'47, 7 "). At eight points in each environment were scored five steams with leaves (CF) and shoots without leaves (SF) to measure the height and number of leaves during 11 months. In the terrestrial phase were collected all individuals of two species in 1m2 (n = 10) for the determination of dry biomass. The density of stems was established by the difference between fresh height and dry height of five stems at each point. (n = 50). For the determination of Ma and Mi in tissues plants, 10 plants of each species were collected and made composite samples. The stems of M. arborescens showed higher growth rate comparing to M. linifera (F = 4.85, p <0.05), but the growth rate of shoots did not differ between species (F = 3.22 p> 0.05). The biomass among species was not significantly different (F = 0.22, p> 0.05). The stem density was higher in M. arborescens (0.10g/m3) than in M. linifera (0.05 g/m3). Flowering and fruiting occur in two peaks, one in phase aquatic and another in the terrestrial phase. There was little reduction in chlorophyll (less than 10%) in the species during flooding. There was also a reduction in nutrient concentrations of 23% (Ma) and 27% (Mi) in M. arborescens, and 14.21% (Ma) and 32.72% (Mi) in M. linifera. There were differences in the pattern of growth and size structure. The results indicate that the species M. arborescens has no restrictions for growth in igapó. Detailed investigations on the evolution and genetics of these two species are required which may elucidate its differential distribution in Amazonian floodplains.