DIFFERENCES IN NITROGEN REQUIREMENTS OF TWO CLONES OF CONVOLVULUS ARVENSIS IN VITRO

Various nitrogen sources were shown to alter the growth and modify nitrate reductase activities of stem callus tissue derived from two clones of Convolvulus arvensis L. (field bindweed). Callus from a Washington (S) clone grew better and had a higher level of nitrate reductase activity than callus from a New Mexico (R) clone when nitrate was the only source of nitrogen available in the culture medium. The addition of glycine to the culture medium decreased growth of the R clone and increased growth of the S clone, but glutamic acid repressed growth of both clones. An amide source of nitrogen such as glutamine or asparagine, or ammonium was required to produce maximum growth of both bindweed clones. Glutamine increased nitrate reductase activity in the two clones, and glycine increased nitrate reductase activity in the S clone but decreased it in the R clone. Glutamic acid decreased nitrate reductase activities in both the R and S tissues.