Effect of Cu Toxicity on Growth of Cowpea (Vigna unguiculata)

Abstract

Accurate determination of the rhizotoxicity of Cu in dilute nutrient solutions is hindered by the difficulty of maintaining constant, pre-determined concentrations of Cu (micromolar) in solution.The critical Cu 2+ activity associated with a reduction in the growth of solution-grown cowpea (Vigna unguiculata (L.) Walp. cv Caloona) was determined in a system in which Cu was maintained constant through the use of a cation exchange resin. The growth of roots and shoots was found to be reduced at solution Cu 2+ activities ≥ 1.7 µM (corresponding to 90 % maximum growth).Although root growth was most likely reduced due to a direct Cu 2+ toxicity, it is considered that the shoot growth reduction is attributable to a decrease in tissue concentrations of K, Ca, Mg, and Fe and the formation of interveinal chlorosis. At high Cu 2+ activities, roots were brown in color, short and thick, had bent root tips with cracking of the epidermis and outer cortex, and had local swellings behind the roots tips due to a reduction in cell elongation. Root hair growth was reduced at concentrations lower than that which caused a significant reduction in overall root fresh weight.Abbreviations: CDTA -cyclohexane-1,2-diaminetetra-acetic acid; DI -deionised; EC -electrical conductivity; I -ionic strength; ICPAES -inductively coupled plasma atomic emission spectrometry; ICPMS -inductively coupled plasma mass spectrometry

Toxic effects of Ni2+ on growth of cowpea (Vigna unguiculata)

“…These observations are in general agreement with those reported for Ni toxicity in white clover, ryegrass, and cabbage (Yang et al 1996), tomato (Lycopersicon esculentum L.) (Palacios et al 1998), and fenugreek (Parida et al 2003). Interestingly, although the primary site of Ni 2+ toxicity in cowpea appears to be the shoot, the primary site of Pb 2+ and Cu 2+ toxicity in cowpea appears to be the root Kopittke and Menzies 2006). Nevertheless, all three trace metals have been shown to have a markedly similar influence on cowpea tissue nutrient concentrations.…”

“…It is therefore concluded that the primary site of Ni 2+ toxicity in cowpea is in the shoots, with the observed reduction in root mass possibly the result of a decrease in the translocation of carbohydrates to the roots as suggested by Baccouch et al (1998). This is in contrast to that reported in cowpea for Cu 2+ toxicity (Kopittke and Menzies 2006) and Pb 2+ toxicity , where the root was considered to be the primary site of toxicity.…”

“…This value may be compared to 10 μM Ni for lettuce (Lactuca sativa L.) (Heikal et al 1989) and 17 μM Ni for bean (Phaseolus vulgaris L.) (Piccini and Malavolta 1992). A comparison of this critical Ni 2+ toxicity (1.4 μM) activity to that established for Cu 2+ toxicity (1.7 μM (Kopittke and Menzies 2006)) and Pb 2+ toxicity (0.2 μM for the shoot, and 0.07 μM for the root )) under similar experimental conditions in the present study indicates that for cowpea, Ni 2+ is of similar toxicity to Cu 2+ but is less toxic than Pb 2+ . However, the relative toxicity of trace metals is dependant upon the plant species (Seregin and Kozhevnikova 2006) so these findings should not be extrapolated to other species.…”

Influence of Demographic Location and Solvent Extraction on Pharmacognostical Assessment and Identification of Conessine Content in Different Parts of Holarrhena antidysentrica Through HPTLC Analysis

“…Furthermore Cu is required for the protein components of several enzymes 32 but in excess quantities, it is highly toxic to plant growth, resulting in complete inhibition of growth. 33 Our present study also resulted the less content of Cu in the raw HA plant sample than Fe and Zn which may reduce the accumulation of toxic substances like Ni, Cd, Cr and Pb which are well known heavy metals in soils for their cumulative accumulation and adverse effect on plant health. Macroscopy and Microscopy are the preliminary step for the standardization and based on that arrangement of anatomical structures are identified which further revealed the plant species identification.…”

Contamination of Detained Sediment in Sustainable Urban Drainage Systems

“…Guideline and threshold values chosen for further field data set analysis were selected by relative proximity to the field sample sites (UK), placing priority on use of the UK ICRCL information followed by EU information. References: [28][29][30][31][32][33][34][35]. Note: all values are mg/kg of dry weight sediment or soil.…”