Phosphorus has a direct effect on table grape yield. Where phosphorus is naturally low in soils, fertilizer phosphate increases berry set and crop yield.
Potassium is involved in transportation of photosynthetic products from leaf to different organs of crop, thus it determines berry growth and yield. It has been shown to increase general berry yield and bunch weight by between 24 to 44%.
Boron plays an important role in table grape fruit set. It is quickly taken up from the soil, but is relatively immobile in the plant, so foliar sprays should be applied just prior to and immediately after flowering to ensure correct pollination and a full table grape bunch number. Deficiencies of boron can seriously affect table grape production, by causing poor bunch number, with large and small berries on the bunch. Thus application of sufficient boron is essential to increase growth and yield.
Applications of iron (e.g. as chelates through soil application of Fertigation) can be used to increase early leaf production and vine productivity. Application of sufficient amount of iron resulted in higher growth and increase of grape berry weight. Keep in mind though that over-application can have a negative effect. A high iron content in the soils can also reduce manganese uptake, which ensures better berry development.
Zinc has a positive effect on berry weight in store.