The effect of different irrigation water and nitrogen levels on yield and alternative bearing in pistachio

This study was carried out betveen 1999 and 2002 at Pistachio Research Institute experimental field area. In the study, different irrigation intervals (Ii=7 days, Iî=14 days) and nitrogen concentrations (Ng,N0,Ni,N2,N3) and different crop coefficients (Kcpi=0.60, Kcp2=0.90) were used. The nitrogen treatments were applied as 0, 10, 15, 20 mg/1. For Ng treatment, fertilizers were given in February under the tree canopy as a pure matter of NPK 500-600-400 gram per tree. The other fertilizer doses were given with irrigation water by using fertigation technology. The irrigation water was calculated according to free open water surface evaporation and wetted percent was assumed as % 30 of allocated full area per tree. Different amount of irrigation water was applied during the experimental years. The amount of irrigation water was changed between 311-1164 mm according to irrigation interval used. Also the crop evapotranspiration was estimated with 1228-467.6 mm maximum and minimum values respectively. On the 7N390 treatment, the highest monthly evapotranspiration was calculated in July 290 mm and the references evapotranspiration was 166 mm at the same month. The maximum and minimum values of Ko for the same treatment in July and November were calculated as 1.51 and 0.39. According to the results, the highest yield values were optained in I2 with 18.32 and 12.02 kg per tree in 2000 and 2001. Uzun variety used in the treatment was showed relative periodisity due to its genetic charecterisation. The highest periyodisity index value was estimated as Ö.766 for the treatments receiving nitrogen and irrigation water and as 0.627 for traditional treatment. The yield response factor was 0.95 on pistachio for 1999 and 2002.Keywords : Fertigation, dnp irrigation, Pistacia veraL., evapotranspiration, yield response factor