PHOSPHORUS AND POTASH EFFECTS ON WHEAT CROP UNDER THE INFLUENCE OF VARIOUS IRRIGATION LEVELS IN ARID REGIONS OF ALGERIA

Three field experiments were carried out at the experimental Station of Adrar, during three successive growing seasons 2013/2014 to 2015/2016. The aim of this study was to investigate the relationship between the water supply levels and phosphorus and potash applications. The experimental design was a split plot design with three replications. The main plots were five irrigation levels (50, 70, 90, 100 and 120% of reference evapotranspiration (ET0)), while the sub- plots contained four fertilization treatments: control (T0), K2O (T1), P2O5 (T2) and K2O + P2O5 (T3). The obtained yields were 5.64, 5.37 and 7.87 t ha-1, during the three consecutive seasons. They were significantly affected by phosphorus apply (P <0.01) during the all trial seasons. No significant effect of potash was observed during the first season. Its effects were significant (P <0.05) and highly significant (P <0.01) during the second and the third season respectively. Water treatment effects were significant on yield and almost all its yield components. The highest water efficiency was recorded when water apply was close to 100 % of MET and elements N P K are available.