Phytotoxicity Level and Effects of Arsenic Phytoextraction using Helianthus Annuus L. (Sunflower)

Abstract

Arsenic is one of the most deadly contaminants polluting the environment in many countries of the world today. It occurs naturally in many ores (Copper, Lead, Gold etc.), but human activities (like explosions, mining, pesticides applications etc.) and natural occurrences (like volcanoes, micro-organisms activities) have increased its amount in the environment to lethal levels. This research involved the growing of sunflower plants Helianthus annuus L. collected from the Institute of Agricultural Research and Training (IAR&T) on various concentrations of Arsenate contaminated soil for Arsenic phyto-extraction for seven weeks to know the phyto-toxicity level of Arsenic on sunflower (an Arsenic hyper-accumulator). After several observations and statistical evaluations using the Analysis of Variance, it was discovered that as from 2.0g – 3.0g of Arsenate per kg of soil, 0% germination occurred. Between 0.75g – 1.5g of Arsenate per kg of soil, the percentage germination was 10% - 50% (not significant) and percentage survival was 30% (not significant). Furthermore, between 0g – 1.5g of Arsenate per kg of soil, there was a percentage germination of 60% - 100% (significant) and a percentage survival of 60% - 100% (significant). Hence, for efficient and appreciable Arsenic phyto-extraction from an Arsenate contaminated soil using Sunflower a concentration of 0.5g and below of Arsenate per kg of soil should be ensured. As from 0.75g of Arsenate per kg of soil (Phytotoxicity level) the effects of Arsenic phyto-toxicity observed are delayed germination, wilting, drying-off, damping-off, foliage chlorosis and necrosis, reddening etc.

Keywords: Phytoextraction, phytotoxicity, arsenic, sunflower, arsenate contaminated soil