Exogenous application of salt (NaCl) inhibit antioxidative system in Cd-treated watercress (Nasturtium officinale R. Br.)

International audienceThis research simulates conditions found in metal-contaminated sites also affected by a high concentration of salt. For these reasons, several exogenous doses of NaCl were used to treat Cd-stressed Nasturtium officinale R. Br. We have chosen Nasturtium officinale R. Br which is a hyper accumulator plant of metals (based on literature). Data suggested induction of oxidative stress under Cd treatment and demonstrated watercress's capacity to upregulate its antioxidative defense. Superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxidase (GPX) activities were stimulated by Cd. Supplementation of (100, 200, 300 mM NaCl) simultaneously with 1 MCd to six weeks aged Nasturtium officinale R. Br caused growth inhibition, reduction of photosynthetic pigment contents and a significant increase of Malonyldialdehyde (MDA) and hydrogen peroxide (H2O2) ones in leaves. Increase of NaCl dose reduced Cd tenor in Nasturtium officinale leaves. Moreover, a dramatic lost of antioxidant system efficiency was detected in these plants. Rise of salinity concentration significantly inhibited SOD, CAT, APX and GPX activities in Cd-treated Nasturtium officinale R. Br

Fungal Consortia Mediated Bio-Treatment of Organic Matter and Metals Uptake from Sewage Water: Maize Agro-Physiological Assessment

The present investigation aims to improve the efficiency of fungal mono- and mixed cultures in removing organic pollutants and metals from sewage water (SW) for further maize plant response assessments. The reduction in the organic load from the SW was harnessed using a co-culture consortium consisting of Aspergillus niger (KB5), Sordariomycetes sp. (D10), and Coniochaetaceae sp. (LB3). The testing results had evinced removal of up to 88% of the organic matter and more than 96%, 91%, 80%, and 47.6%, of removal percentages for Copper (Cu), Nickel (Ni), Cadmium (Cd), and Lead (Pb), respectively, with the developed fungal consortium [KB5 + D10 + LB3]. After treatment and lab experiments, a reuse of treated and untreated SW for plant irrigation was evaluated towards improving maize plant growth. Irrigation was conducted in pot experiments with three types of water: clean water (Control), untreated (USW), and treated SW by fungal consortia (TSW) and by station treatment plant STP (TSWP) using the randomized complete block (RCB) experimental design. Results of the pots trial revealed that the morphological parameters of SW-irrigated plants are slightly improved compared to water-irrigated plants. Data regarding assimilating area attributes indicated that the most significant enlargement of the assimilation area was observed with TSW-D (1/4) irrigation by 1051 cm2, followed by TSWP-D (0) by 953.96 cm2, then USW-D (1/4) by 716.54 cm2, as compared to plants irrigated with clean water (506.91 cm2). On average, the assimilation areas were larger by 51.76%, 46.86%, and 29.25% in TSW, USW, and TSWP-irrigated plants, respectively. Thus, SW irrigation supports the required qualities and quantities of microelements and water for plant growth. Oxidative stress assessment showed that irrigations with treated SW caused a significant decrease in both enzymatic and non-enzymatic antioxidants, depicting that the treatment lowered the stress of sewage water