The effect of drought stress and different amounts of nitrogen and potassium fertilizers on productivity of forage sorghum variety speedfeed

Subject Areas : crop production

fatmeh khezerloo ¹ (دانش آموخته دانشگاه آزاد اسلامي)

Received: 2010-08-17 Accepted : 2011-07-11 Published : 2010-07-01

Keywords: Forage Sorghum, Nitrogen, Potassium, Water stress, yield ,

Abstract :

To investigation the effects of water stress and different rates of nitrogen and potassium fertilizer on yield of forage sorghum variety speedfeed (Sorghum bicolor L. Moench) in second cropping , a field study was conducted at 2009 cropping season in KhoyResearch Station. Experiment was carried out using a split plot design , used on RCBD with 3 replications. Treatments consisted three level of water stress (I1=70 , I2=105 , I3=140 )mm evaporation from the pan of class A, as main factors and sub factors consisting nitrogen consumption in three levels (N1=300),(N2=400),(N3=500) kg/ha as source, urea and potassium in three levels (K1=0),(K2=150),(K3=300)kg/ha as source K2So4, of course foliar application urea in amount 33 kg/ha in stage doughying grain in single treatment and phosphorous consumption based on fertilizer recommendation in amount (P=50)kg/ha as source Tsp in total treatment was carried out. Investigated characteristics were , plant height , stem diameter, leaf number, tiller number per plant, leaf to stem ratio , fresh fodder and biologic yield ear yield, relative water content (RWC) and chlorophyll content. The results analysis of variances showed that plant height, fresh fodder and biologic yield, chlorophyll content, relative water content (RWC) impressed after of stage leaf 4-5 by water stress , but significant difference was not observed in other traits. Applying amounts of fertilizers reduced significantly plant height, stem diameter, tiller number, fresh fodder and biologic yield, ear dry weight, chlorophyll content. So that applying 500 kg/ha urea and 300 kg/ha K2SO4 and 50 kg/ha TSP reduced increase yield.