3% foliar potassium nitrate increases yield in grapes

This study was performed in Izmir, Turkey, in two consecutive years to determine the effects of KNO₃ foliar applications on yield and leaf contents in Sultani seedless grapes. The soil texture was sandy-loam with a pH of 6,3.

Treatments were control, 1%, 2% and 3% KNO₃ and 1% KH₂PO₄ + NH₄H₂PO₄, all applied as successive foliar sprays every week in June. KNO₃ foliar applications increased yields in 1996 and 1997 (Figure 1).

Highest yield was obtained for the 3% KNO₃ treatment, the yield increased by 35% in 1996 and 17% in 1997 compared to the control. The results showed that potassium nitrate foliar applications lead to considerable increases in yield of Sultani seedless grapes.

Figure 1. Effect of foliar applications on grape yield in 1996 and 1997.