ACETOHYDROXYMATE INDUCED NITROGEN DEFICIENCY IN N-2-FIXING PIGEON PEA

Acetohydroxymate (AHM), a specific inhibitor of urease was applied to the rooting systems of nodulated pigeon pea (ureide symbiosis) and alf alfa (amide symbiosis) for a period of 25 days. Pigeon pea suffered ch lorosis, and a reduction in plant growth, dry weight and total nitroge n content, while these parameters were unaffected in alfalfa. Whereas the nitrogenase (EC 1.7.99.2) activity of these two plant nodules was unaffected due to AHM, urease (EC 3.5.1.5) levels were markedly reduce d, consequently urea accumulated in all parts of the pigeon pea. These results suggested that AHM blocked nitrogen assimilation into plant p rotein. Ureide metabolism in pigeon pea may be via the allantoicase pa thway rather than the allantoate amidohydrolase pathway.