The interaction of arsenic (As) and chromium (Cr) influences growth and antioxidant status in tossa jute (Corchorus olitorius)

Abstract

Co-occurrence of arsenic (As) and chromium (Cr) is observed worldwide. However, their combined effects on plant physiology are not well documented. This experiment was designed to study both individual and combined phytotoxicity of arsenic (As) and chromium (Cr) in jute in terms of plant growth, net photosynthesis, chlorophyll content, oxidative stress and antioxidant enzyme activities. Two jute varieties, O-795 (Cr-tolerant) and O-9897 (Cr-sensitive), were grown under various level of As and/or Cr in pots under greenhouse condition. As or Cr stress significantly decreased plant growth, chlorophyll content, chlorophyll florescence (Fv/Fm), photosynthetic rate (Pn) and caused oxidative damage compared to control, indicated by increased MDA and H2O2 contents. The activities of superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), glutathione reductase (GR) and catalase (CAT), were dramatically increased in both varieties compared to control. Moreover, less severe inhibition of plant growth and oxidative damage was observed in O-795 than in O-9897 indicating variety O-795 had more efficient defense system to mitigate heavy metal induced oxidative stress. The combined stress of low level of As (50 mg kg-1) plus Cr treatment caused less inhibition of plant growth and alleviated oxidative stress, in both varieties compared to Cr stress alone. In contrast, high level (100 mg kg-1) As plus Cr caused a further decreased plant growth and chlorophyll content, increased MDA and H2O2 contents as well as antioxidative enzymes activities significantly (P ≤ 0.05). These results suggest that the combined toxicity of low level As plus Cr in jute is lower than that of individual Cr or As. As exposure up to 50 mg kg-1 is supposed to be useful in mitigating Cr toxicity and more than 50 mg kg-1 had the synergistic toxic effect.