LETTUCE RESPONSE TO NITROGEN FERTILIZERS AND ROOT MYCORRHIZATION

Maria Geneva, Luba Nenova, Marieta Hristozkova, Ira Stancheva, Ivanka Mitova, Janet Mincheva

Abstract: Two lettuce varieties Ysi 43301/5638 (green lettuce) and Matador 5635 (red lettuce) plants were grown as a spring crop under glasshouse conditions in order to evaluate the effect of different synthetic nitrogen fertilizers applied solely and in combination with mycorrhizal fungi on the yield and quality. Mineral nitrogen was applied as NH4NO3, CO(NH2)2, Ca(NO3)2 and (NH4)2SO4 and an inoculum of arbuscular mycorrhizal fungi, Glomus intraradices EEZ 01 was used. The effect of mycorrhizal inoculation on plant biomass more clearly distinguished in variety Ysi 43301/5638, where biomass accumulation significantly increased in the treatments with CO(NH2)2, Ca(NO3)2 and (NH4)2SO4 in combination with Gl. intraradices. The most favorable effect on the plant biomass of the other variety Matador 5635 was observed in plants inoculated with Gl. intraradices and fertilized with (NH4)2SO4. Deterioration of lettuce quality (reduction of protein content, soluble sugars and increased nitrate content) was observed in Ysi 43301/5638 in the treatments with urea in combination with mycorrhizal fungi. The strong reduction in the values of pigments also in both varieties was estimated as a result of fertilization with urea in non-mycorrhizal and mycorrhizal treatments. The interactive action of nitrogen assimilatory enzymes - nitrate reductase and glutamine synthetase are not in accordance with biomass accumulation.

Keywords: arbuscular mycorrhizal fungi; Lactuca sativa L.; nitrogen assimilatory enzymes; nitrogen fertilizers

Date published: 2017-04-28