CONGRESO
LXV CONGRESSO NACIONAL DE BOTÂNICA
BOTÁNICA
XXXIV ERBOT - Encontro Regional de Botânicos MG, BA, ES 18 A 24 DE OUTUBRO DE 2014 - SALVADOR - BAHIA - BRASIL
Latinoamericano de
Botânica na América Latina: conhecimento, interação e difusão
PHOTOSYNTHESIS AND GROWTH OF PLANTS OF
BORRERIA VERTICILLATA (L.) G.F.W. MAYER
(Rubiaceae), FROM MINE AND NON-MINE SITES,
EXPOSED TO ARSENIC
AUTOR(ES):Samara Arcanjo e Silva;Naiara Viana Campos;Priscila
Gonçalves Malta;Ivan Becari Viana;Jaime Wilson Vargas de Mello;Aristéa
Alves Azevedo;
INSTITUIÇÃO:
Universidade Federal de Viçosa
Borreria verticillata (L.) G.F.W. Mayer is an arsenic (As) tolerant and
promising species for revegetation of As contaminated areas. Plants that
naturally grown in mine site (MS) are usually more tolerant than plants
from non-mine site (NMS). We aimed to compare the potential of MS and
NMS plants of B. verticillata for use in revegetation of contaminated areas,
by analyzing the As effects on photosynthesis and growth of these plants .
Plants were grown in Clark’s nutrient solution containing 0, 33 and 66 M
of As for 4 days. The chlorophyll a fluorescence parameters and gas
exchange were measured with a portable Mini PAM fluorometer and an
infrared gas analyzer (IRGA), respectively, on the 2nd and 4th treatment
day. The shoot height (SH), root volume (RV) and total fresh weight (TFW)
were measured at the beginning and end of the experimental period, and
the differences during this time were used to obtain the relative growth of
the plants. To measure the total dry weight (TDW) the plants were dried in
a forced air oven at 70 °C. The contents of As and nutrients in root and
shoot were determined by atomic emission spectrometry with inductively
coupled plasma (ICP OES). The most severe injury induced by As was in the
photosynthesis and plant growth of NMS plants. Symptoms of As toxicity
were more pronounced in roots, which showed browning and a gelatinous
aspect in both populations. Arsenic reduced in the relative increase of SH in
NMS plants, and RV and TFW in both populations. However, the TDW did
not differ among treatments, indicating that the mass reductions were due
to water deficit generated by root damage. Plants from NMS exposed to As
showed reduction of Ca, K, Mn and Fe contents in the shoots. Arsenic
affected mainly the biochemical step of photosynthesis, indicated by the
reduction of stomatal conductance and consequently of the ratio of internal
and external CO2 concentration, CO2 assimilation, and transpiration rate.
The coefficient of non-photochemical quenching increased on the 2nd day of
As exposure in NMS plants, and avoided further damages in the
photosynthetic apparatus. The reduction of water and nutrients contents in
NMS plants exposed to As help explain the As effects on photosynthesis of
these plants. The results demonstrate that the MS plants are more tolerant
to As, and therefore more promising for revegetation of areas with low
concentrations of the metalloid. (FAPEMIG, CAPES)