关键词: 田菁, 根瘤, 固氮活性

Abstract: Sesbania cannabina interplanted in orchard as summer green manure appeared nodules after 10-15 days' growth. Their taproots and lateral roots developed abundant nodules. The total amount of nodules was estimated to be 30 kg per mu. The nitrogen fixiug activity,as determined by acetylene reduction assay, reached a maximum at vegetative period, and declined during flowering and podding stages because the taproot nodules began to rot. Soil drought reduced moisture content and nitrogenase activity of nodules. The optimum temperature for nitrogen fixation of nodules was 25℃ and the nitrogenase activity markedly decreased below 12℃ or over 35℃. Approximately 7.6 kg nitrogen per mu was fixed by nodulated S.can-nabina during vegetative period under our experimental conditions.

Key words: Sesbania cannabina, nodules, nitrogenase activity