The purpose of fruit analysis:
The position and size of fruit on the tree has a great influence on the composition and quality. Normally the fruit inside the tree is usually of a poorer quality. The reason for the analysis must therefore be clear because it influences the sampling. Fruit from different cultivars and bearing positions must not be mixed.
Fruit analysis 14 days before harvest can indicate the probability of incidence of storage disorders and therefore of the keeping quality of the fruit. About 20 fruit that are representative of the orchard are sampled and the laboratory must determine the mean fruit mass. Where it is known that fruit from different parts of the orchard have different storage qualities, they should be sampled separately. The core is not included in the analysis but the peel is. The sample is analysed for Nitrogen, Phosphorus, Potassium, Calcium and Magnesium and the result expressed as mg element per 100g fresh mass. This analysis however does not offer the possibility of corrective action during the season. For this purpose small fruit analysis must be performed much earlier. Fruit analysis however can, as with leaves, be used to modify the maintenance nutrition program for the following season.
Small fruit are usually sampled at the end of the cell division stage (60 days after full bloom) from selected trees that are representative of the orchard. Fruit size at that stage is about 50-70 mm. Collect about 50 fruit per sample and the analysis laboratory must determine the mean fruit size. Where it is known that fruit from certain parts of the orchard differ in their storage capability they must be sampled separately. The whole fruit including the skin and core is analysed. The sample is analysed for Nitrogen, Phosphorus, Potassium, Calcium and Magnesium and the results expressed as mg element per 100g fresh mass.
The position on the tree from where fruit are sampled is of critical importance because the position on the tree has a major effect on the composition of the fruit. Fruit from different bearing positions must not be mixed in the sample. The interpretation of the analysis figures is also important because weather conditions in South Africa can vary significantly over short periods between the time of sampling and the time of harvest.
For more information, please contact:
Bemlab: 021 853 1490