Senanayake, L.2020-09-022020-09-021991Tropical Agriculturist, 147:p.33-39https://dl-doa.nsf.gov.lk/handle/1/2665PLANT SCIENCE AND PRODUCTIONCowpea (Vigna unguiculata)NitrogenNitrogen fixationNodulationEffect of nitrogen on nodulation and symbiotic nitrogen fixation in cowpea cultivar MI 35-A laboratory studyArticle