Phosphorus has a direct effect on yield. As the season develops, leaf phosphorus concentration decreases, with phosphorus being transferred to the fruit. As fruit weight increases, so does the amount of phosphorus in the fruit. Thus, it is important to ensure supplies are not limiting throughout the season to maintain good growth and steady accumulation of phosphorus in the fruit.
Increasing Apple Weight
Apple weight is an important element for increasing yields. Provided that a desired quality is maintained, the aim of growers is to produce heavier fruits. Crop nutrition plays an important role on increasing apple weight.
Crop Nutrition and Apple Weight
Nitrogen
Nitrogen form is important for yields. Calcium nitrate forms are readily available and can produce higher yields. Compared to ammonium nitrate, calcium nitrate also has an effect on maintaining soil pH, improving tree growth and ensuring other nutrients are more available. Calcium activates enzymes and is essential for cell division, elongation, and fruit growth.
Phosphorus
Potassium
Where supplies are inadequate, potassium yield responses have been recorded following applications of up to 600-700 g/K/tree in low density orchards. Some of this yield increase comes from an increase in fruit weight. However, applications need to be adjusted according to soil potassium levels: where levels are high, high K fertilizer rates may lead to a yield reduction, mainly due to a reduced uptake of other cations (Mg and Ca).
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