Effect of irrigation cut-off and different nutritional systems on yield and yield components of spring safflower in Yasouj region

Lack of water is one of the main factors in the reduction of agricultural production at arid and semi-arid regions of the world. Nitrogen is one of the most important nutrients and key factor in achievement to favorable yield in crops. Organic sourceses in combined with chemical fertilizer can lead to soil fertility and increase crop production. Thus it seems necessary investigate the effect of different nutritional systems (Organic, chemical and integrated) and irrigation cut-off on yield and yield components of safflower.
The experiment was done on spring safflower (Isfahan-14 cultivar) as slit-plots arranged in a randomized completed block design with three replications. The main plot were including irrigation at the four levels (S0: full irrigation, S1: irrigation cut-off at the stem elongation stage, S2: irrigation cut-off at the flowering and anthesis stage and S3: irrigation cut-off at the grain filling stage) and subplot including different nutritional systems in the six levels (N0: no fertilizer, N1: 100 kg pure nitrogen from urea, N2: 75 kg pure nitrogen from urea kg nitrogen from organic manure, N3: 50 kg pure nitrogen from urea kg nitrogen from organic manure, N4: 25 kg pure nitrogen from urea kg nitrogen from organic manure and N5: 100 kg nitrogen from organic manure) (Organic manure was used poultry manure). This experiment was measured LAI, yield, yield components and water use efficiency.
The obtained results indicated that irrigation cut-off at different growth stages had significant effect on measured traits; so at treatment of irrigation cut-off at the flowering and anthesis stage, number of fill grain per head than full irrigation treatment decreased 21.5 percent. Also yield and yield components at integrated nutritional systems were more than chemical and organic nutritional systems. The highest grain yield at full irrigation, irrigation cut-off at the stem elongation stage, irrigation cut-off at the flowering and anthesis stage and irrigation cut-off at the grain filling stage treatments was obtained from integrated nutritional systems of N2 (4291.7 kg ha-1), N2 (3211.7 kg ha-1), N2 (2653.3 kg ha-1) and N2 (3603.4 kg ha-1), respectively. The weater use efficiency at the S1 and S3 treatments in the all nutritional systems increased than S2 treatment.
Use of organic manures in combined with chemical fertilizers by moderating the effects of drought stress led to improvement yield and yield components of safflower under irrigation cut-off conditions. Therefore grain yield at S2 treatment in different nutritional systems of N2 and N3 was similar treatment of full irrigation and chemical nutritional system. Based on obtained results can stated that in safflower planting can by irrigation cut-off at grain filling stage and application of integrated nutritional systems somewhat compensated the decline caused by lack of available water.