Growth and Chemical Composition of Beta Vulgaris Var. Dcla, Brassica Oleracea Var. Capitata and Lactuca Sativa Treated With Industrial and Municipal Wastes.

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1998-06

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Addis Ababa University

Abstract

The purpose of the study was to examine the effects of industrial and municipal liquid wastes on the growth (leaf number, leaf length, and leaf width), biomass productivity and plant tissue composition of three different vegetable species. Furthermore, the study attempted to detect the toxicity symptoms and concentration of some of the heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) on the vegetables as a result of the treatment. Three different vegetable species Beta vulgaris var. cic/a (swiss chard), Lactllca sativa (lettuce) and Brassica oleracea var. capitata (cabbage) were allowed to grow under three different treatments, i.e., tap water(control), industrial and municipal liquid wastes (experimental). Fluvial soil, which was free from industrial and municipal liquid wastes was sample, for experiment. Industrial and municipal liquid wastes were brought from Akaki textile factory and Bulbulla river respectively. The experiment was conducted under glasshouse condition. The growth parameters of the vegetable species were recorded at every seven days interval. Plant material analysis has been administered at two stages, after the 6th week and during harvest. The descriptive statistics, and analysis of variance were applied to analyze the effect of the treatments on the vegetable species. The physical and chemical properties and concentrations of heavy metals in the soil samples were determined using laboratory analysis. The concentrations of heavy metals were analyzed using atomic absorption spectrophotometer (AAS). The result showed that vegetables treated with municipal liquid waste exhibited a relative better growth in leaf number, leaf length, leaf width and shoot biomass productivity than the other two treatments. Similarly, the distribution of total organic carbon, organic matter, total nitrogen, available phosphorus, exchangeable bases, soil pH and CEC were observed to be significantly high in the soil samples treated with the municipal liquid waste than tap water and industrial liquid waste treated soils. In addition, the leaf number, leaf length, leaf width and dry matter yield of vegetables treated with municipal liquid waste were found to have a positive and significant correlation with soil total organic matter, total organic carbon, organic matter, total nitrogen, available phosphorus and exchangeable bases. Yet, except for Cd, and Pb, an increase in the concentration of some of the heavy metals (Cr, Cu, Ni, Zn) was observed on the analyzed soil samples treated with both industrial and municipal liquid wastes. On the other hand, however, the research findings indicated that the difference in the level of concentration (accumulation! of heavy metals as a result of industrial and municipal liquid wastes application, between the sampled vegetable species was insignificant for Cd, Ni, and Zn. However, the concentration difference for Cr, Cu and Pb within and between the vegetables was significant. In the study, neither toxicity symptoms nor reduction of yields in biomass was observed in all sample vegetables. Furthermore, from the findings it was observed that the degree of concentration of heavy metals in each of the sampled vegetables was below the range of toxicity level.

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Biology

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