Limited Irrigation and Phosphorus Fertilizer Effects on Yield and Yield Components of Grain Sorghum (Sorghum bicolor L.var. Kimia)

Abstract

Prevailing drought stress is one of the main agricultural problems in arid and semi-arid regions of the world. To evaluate the effect of limited irrigation systems and phosphorus fertilizer on yield and yield components of grain sorghum (Kimia), the crop was sown in the Research Farm of College of Agriculture, University of Tehran in Karaj/Iran. The treatments comprised of different limited irrigation regimes applied at different vegetative and generative growth stages of sorghum along with different levels of phosphouors fertilizer viz: contol (no fertizer application); sole chemical phosphorus fertilizer of ammonium phosphate (250 kg/ha) and a mixture of 50% ammonium phosphate (125 kg/ha)+ phosphorus sulobilizing bacteria. The highest grain yield of 7 t/ha was obtained from the control irrigation treatment (no drought stress) when biological phosphorous fertilizer was applied along with 50% of the required chemical fertilizer (ammonium phosphate). Severe drought stress at generative growth stage along with sole ammonium phosphate application led to the least grain yield of less than 0.5 t/ha. Severe limited irrigation during vegetative growth stage and moderately limited irrigation during generative stage (despite 30% grain loss) could produce a reasonable crop with a tremendous water saving with high water use efficiency.