Toxicological effect of arsenic (V) on growth and histology of duckweeds (Lemna minor)

Date of Publication

1992

Document Type

Bachelor's Thesis

Degree Name

Bachelor of Science in Biology

College

College of Science

Department/Unit

Biology

Abstract/Summary

Duckweeds (Lemna minor) were used as a representative of plant species for their being sensitive to a wide variety of toxicants. Test species was grown under laboratory light condition of 11:13 light and dark period in an aqueous dilution of Hoaglands culture media (1:1 vol/vol with distilled water) at pH of 7.0. This laboratory culture environment was found suitable for the maximum normal growth of duckweed (SI value of 2.5).Toxicological effects of varying concentrations of As (V) ranging from 0.0, 0.1, 1.0, 3.0, 5.0, 10.0, and 25.0ppm was assessed based on growth measured in terms of frond production and biomass content. Histological changes in treated duckweed with 25.0ppm As were also noted. In As concentration of 0.1-1.0ppm, growth of Lemna minor approximated the control. However, concentration of As from 3.0ppm or higher is lethal to duckweeds as evidenced by an inhibition of growth. An overall reduction of 20-40 percent in biomass over the control at 0.1-25.0 ppm As was observed. Histological studies were conducted on treated duckweed showing a generalized chlorosis accompanied by disruption in chloroplast integrity and degeneration of intact chloroplast. The cells in the vascular bundle were proliferated or severely collapsed and disruption of the mesophyll and epidermal layer caused a 24 percent reduction in the thickness of duckweed frond. Accumulation of As by duckweeds may enhance the toxic effect on their histological processes which influences their total process of growth and survival.

Abstract Format

html

Language

English

Format

Print

Accession Number

TU05620

Shelf Location

Archives, The Learning Commons, 12F, Henry Sy Sr. Hall

Physical Description

62 numb. leaves ; Computer print-out.

Keywords

Arsenic--Toxicology; Weed control

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