EFFECT OF NITROGEN-SOURCE ON GROWTH AND MORPHOGENESIS OF 3 MICROPROPAGATED POTATO CULTIVARS

Different nitrogen sources (NO3-, NH4+, glutamic acid and their combin ations) influenced the growth and morphogenic responses (node number, shoot length, and stem, leaf and root dry weight) of three micropropag ated potato cultivars (Spunta, Kennebec, Huinkul). Addition of reduced nitrogen (NH4+ or glutamic acid) in a nitrate medium increased shoot length and leaf number. The large increase in growth in plants fed wit h NO3- NH4+ could be explained by higher organic nitrogen content and enhanced dry matter partition to the shoot. This suggests that reduced nitrogen source is required, at least as a supplement to NO3-, to enh ance N assimilation and growth,