The Potassium Requirement for Growth and Embryogenesis in Wild Carrot Suspension Cultures

Abstract

Abstract A requirement for potassium for growth and forembryogenesis in suspension cultures of wild carrot ( Daucus carota L.) was demonstrated. The concentration of K + required for maximal growth (1 m M ) was less than that required for maximal embryogenesis (20 m M ). Neither Na + nor NH 4 + could replace K + . Ammonium ion enhanced embryogenesis when K + was present at suboptimal levels greater than 1 m M . Nitrogen sources strongly influenced growth and embryogenesis, but the effects of nitrogen were separable from those of K + . Subline differences were noted. Subline CSC‐29 produced nearly half the maximum embryo number in 1 m M K + while CSC‐31 produced no embryos at that K + concentration. Growth of CSC‐29 was slightly repressed by Na + , but no more than by similarconcentrations of K + . Growth of CSC‐31 in 1 mM K + was strongly repressed by Na + . Embryogenesis in CSC‐29 was unaffected by Na + . In CSC‐31, Na + repressed embryogenesis at lower concentrations of K + .