摘要
果园套种田菁作夏季绿肥,出苗10~15天即有根瘤出现,主根和各级侧根都可能结瘤,根瘤数量较多,每亩可达30公斤以上。营养生长期根瘤固氮酶活性较高;花果期由于部分根瘤衰败,固氮活性明显降低。土壤干旱降低田菁根瘤的含水量和固氮活性。田菁根瘤在25℃时固氮活性最高,12℃以下或35℃以上固氮活性急剧下降。营养生长期每亩田菁每天干均可固氮76克,若在苗龄100天时翻埋,可固氮7.6公斤,折合硫酸铵36.2公斤。
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.
关键词
田菁
结瘤
固氮
Sesbania cannabina, nodules, nitrogenase activity