Methane emission from waterhyacinth was studied under natural, laborat
ory and greenhouse conditions. The emission rate varied between 6 and
326 mg m-2 h-1; methane dissolved in surface water (11-61 mug l-1) was
taken up by the plant and eliminated through the plant's ventilating
system largely through the leaves. Although methane emission increased
with increase in the content of dissolved methane, wind velocity, pla
nt surface area and light intensity, there was no proportionality betw
een methane emission and these factors. Methane emission was reduced a
bout 70% in darkness. The optimum pH and soil temperature for methane
production by methanogens was 33-degrees-C. Leaf tissues were most eff
iciently utilized by soil microorganisms for methane production. It ha
s been estimated that in India alone 1.2 Tg of methane are emitted per
year.