AGRONOMICAL AND PHYSIOLOGICAL-ASPECTS OF AMMONIUM AND NITRATE NUTRITION OF PLANTS

Field studies comparing yield responses of crops treated with differen t nitrogen fertilizer types have led to very contradictory results. Th is can be explained by the fact that the application of different form s of nitrogen map affect plant growth via numerous processes in the so il and within the plant. In this review the significance of these proc esses for nutrient availability in soil are briefly outlined. Then, da ta from literature and own results are used to show that an enhanced a mmonium supply may promote certain yield components such as the number of ears per Plant in wheat or the number of kernels per plant in maiz e whereas other yield components such as the number of grains per ear in cereals or the number of tillers in linseed may he adversely affect ed by ammonium supply. These different effects of ammonium and nitrate supply on yield structure of plants are related to physiological chan ges in the plant using a model.