Seasonal variation of soluble carbohydrates and starch in Echinolaena inflexa, a native grass species from the Brazilian savanna, and in the invasive grass Melinis minutiflora

A Souza,Vr Pivello,St Meirelles,Rcl Figueiredo-Ribeiro,Mfa Calió,Cz Sandrin

doi:10.1590/s1519-69842010000200023

A Souza, Vr Pivello + Show 4 more

Open Access

https://doi.org/10.1590/s1519-69842010000200023

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Abstract

Echinolaena inflexa (Poir.) Chase is an abundant C3 grass species with high biomass production in the Brazilian savanna (cerrado); Melinis minutiflora Beauv. is an African C4 forage grass widespread in cerrado and probably displacing some native herbaceous species. In the present work, we analysed seasonally the content and composition of soluble carbohydrates, the starch amounts and the above-ground biomass (phytomass) of E. inflexa and M. minutiflora plants harvested in two transects at 5 and 130 m from the border in a restrict area of cerrado at the Biological Reserve and Experimental Station of Mogi-Guaçu (SP, Brazil). Results showed that water soluble carbohydrates and starch amounts from the shoots of both species varied according to the time of the year, whilst in the underground organs, variations were observed mainly in relation to the transects. Marked differences in the pattern of the above-ground biomass production between these two grasses relative to their location in the Reserve were also observed, with two peaks of the invasive species (July and January) at the Reserve border. The differences in carbohydrate accumulation, partitioning and composition of individual sugars concerning time of the year and location in the Reserve were more related to the annual growth cycle of both grasses and possibly to specific physiological responses of M. minutiflora to disturbed environments in the Reserve border.

Highlights

Biological invasion is a serious threat to the biodi‐ versity of natural ecosystems (Vitousek, 1990)
Perennial African C4 grasses are very successful invaders in savanna areas, as they have traits that give them a strong competitive advantage compared to the native species, such as tolerance to grazing, fire and low soil nutrient availability (D’Antonio and Vitousek, 1992; Williams and Baruch, 2000; Rosas et al, 2006)
In the present work, we investigate the contents of water soluble carbohydrate and starch in vegetative organs of M. minutiflora and E. inflexa har‐ vested from two transects in a restrict cerrado fragment, representing the border and the internal parts of this site, aiming at to correlate carbohydrate accumulation, phy‐ tomass production and the distribution of both species in the cerrado

Summary

Introduction

Biological invasion is a serious threat to the biodi‐ versity of natural ecosystems (Vitousek, 1990). (Molasses grass), which is native to Africa but nowadays is wide‐ spread throughout the tropics (Baruch and Gomez, 1996; D’Antonio and Vitousek, 1992; Hoffmann et al, 2004). This species, as well as other African grasses, holds several traits such as high seed production, effi‐ cient vegetative growth and investment in shoot produc‐ tion (Filgueiras, 1990; Klink and Joly, 1989; Simões and Baruch, 1991) that allow them to form dense mats that exclude many other herbaceous native species (Pivello et al, 1999b). In the present work, we investigate the contents of water soluble carbohydrate and starch in vegetative organs of M. minutiflora and E. inflexa har‐ vested from two transects in a restrict cerrado fragment, representing the border and the internal parts of this site, aiming at to correlate carbohydrate accumulation, phy‐ tomass production and the distribution of both species in the cerrado

Plant material and study area

Determination of starch content

Statistics

Results

Discussion