EFFECT OF THE INTERRACTION BETWEEN NITROGEN, PHOSPHORUS AND POTASSIUM ON GROWTH CHARACTERS AND YIELD OF WHEAT UNDER DRY FARMING CONDITIONS

Two field experiments were carried out at El-Khroub experimental station, east of Constantine, Algeria, to evaluate the effect of N, P, K fertilization and their interaction on growth characters and yield of wheat grown on calcareous soil. The design of each experiment was split-split plot. Urea was applied as folier application to one experiment to evaluate the supplementel application of nitrogen under dry farming conditions. The results showed that the main stem height, number and height  of tillers and number of leaves were varried according to the levels  of  N, P, K fertilization as well as to presence or absence of urea., Straw yield significantly increased due to increasing nitrogen level and potassium fertilization in absence or presence of urea. However, grain yield was significantly increased either with increasing nitrogen level in absence of urea or with increasing phosphorus levels in absence or presence of urea. Straw yield was significantly affected by N * P interaction in absence or presence of urea and N * P * K when urea was applied. However, grain yield was significantly affected by N * P and N * P * K interractions in absence of urea application.