Fizjologiczne reakcje na N–NO3 i N–NH4 odpornych i wrażliwych na triazyny roślin przymiotna kanadyjskiego (Erigeron canadensis L.) [Physiological responses to N–NO3 and N–NH4 of triazine resistant and susceptible plants of horseweed (Erigeron canadensis L.)]

Abstract

Triazine resistant and susceptible biotypes of horseweed (Erigeron canadensis L.) were grown under controlled conditions in nutrient solution with NH₄ or NO₃ ions as nitrogen source. Indicators such as: dry matter, CO₂ assimilation, chloroplasts activity, dark respiration and the content of K, Ca, Mg in the above ground parts displayed lower levels when plants were fed with NH₄ than with NO ions. Reduction of these indicators was stronger for the triazine susceptible plants which grew better than their resistant counterparts when fed with N–NO₃. The triazine resistant plants grown with N–NH₄ contained more protein-N and K than the susceptible ones. Chloroplasts of the resistant plants were also less sensitive to NH₄CL treatment. It is concluded that the resistant plants appear to be more tolerant to NH₄ ions as compared with their susceptible counterparts. For this reason application of ammonium forms of nitrogen fertilization in horticultural practice could favour spreading of triazine resistant horseweed.