Effect of lead on mustard plant.
Reichard, Larry
Lead contamination is a problem in eastern Missouri; an area often
termed the "lead belt". Lead may accumulate in soil, posing a
hazard for children in contact with the soil. Ingestion of bioavailable
lead causes lead poisoning, which leads to impairment of mental
function. Lead is classified as a persistent contaminant, since it binds
tightly with the soil. Land that is left untreated will continue to be
hazardous for many years. Current methods of cleanup can be costly and
ineffective for long-term treatment. One possible method of cleanup is
the use of lead altering bacteria in conjunction with lead resistant
plants. The mustard plant in particular has shown to have some lead
resistant qualities to it. When grown in soil containing substantial
amounts of lead it has been able to thrive and reach maturity within a
normal time frame. Our experiments showed that a 0.5 mM Pb solution
stunted the growth of the plant by at least 43% compared to those plants
with no lead added. From this discovery we decided to add three
different lead resistant bacterial strains to the contaminated soil to
see if the bacteria could enhance plant growth at all. Variovorax
paradoxis, Pseudomonas fluorescens, and an unknown Pb resistant bacteria
were each added to the soil of a mustard plant both with lead and
without lead. The plants that grew the closest to normal were the ones
in lead contaminated soil with the Variovorax paradoxis bacteria while
addition of the other strains showed a decrease in plant growth and in
some cases no growth at all.
* Kulhanek, L. and T. Giblin. Department of Natural Sciences,
Stephens College.