Hill Laboratories can complete mineral, nutritional and residue analysis of fruit.
About this Testing
Mineral Testing of Fruit
The Agriculture Division of Hill Laboratories mainly completes mineral testing of apple fruitlet and apple fruit samples, and also tests green and gold kiwifruit samples. Other fruits such as cherry, persimmon and apricots may also be analysed for a Basic Fruit Profile.
The Basic Fruit Profile includes:
N, P, K, S, Ca, Mg, Na, Fe, Mn, Zn, Cu, B and KMg/Ca, N/P and N/Ca ratios.
The Basic Fruitlet Profile includes:
N, P, K, S, Ca, Mg, Na, Fe, Mn, Zn, Cu, B and KMg/Ca, N/P and N/Ca ratios, DM and Mean Weight.
To analyse other fruit and fruit juices contact the laboratory.
Apple Fruitlet Testing
Mineral analyses trials of fruitlets, and fruit, from New Zealand orchards during the 1990’s suggested that early season fruitlet analysis can help growers to assess the degree of risk of mature fruit having unacceptably low concentrations of calcium. Trials conducted in 1997/98 confirmed the earlier findings and also suggested that apple fruitlet data may be a better indicator of apple storage quality than pre-harvest fruit testing.
Some varieties of apple are particularly susceptible to post-harvest disorders, such as bitter pit, when their mineral composition is out of balance. Apple Fruitlet Analysis
Limitations of Soil or Leaf Tests
Although soil and leaf tests are valuable management tools for maintaining the health and vigour of the apple trees themselves, such tests have proved of limited value for assessing the risk of post-harvest disorders in mature fruit.
Mineral Analysis of Mature Apple Fruit
Mineral analysis of mature fruit is generally a reasonable predictor of storage disorders. For example, low concentrations of calcium in the fruit at harvest have been associated with the storage disorders bitter pit and senescent breakdown in Cox’s Orange Pippin. However, there are only limited remedies available to growers who discover that their fruit has these mineral imbalances at harvest. Apple Fruitlet Analysis.
Other Mineral Elements
In situations where calcium levels are low, it is often useful to consider the level of calcium relative to other minerals such as the ratios of nitrogen to calcium, and (potassium + magnesium) to calcium. In addition to reporting actual mineral levels for their samples, growers who submit apple fruitlets to Hill Laboratories now receive information about ‘normal’ levels of these other minerals, and mineral ratios, based on our analysis of fruitlets of the same variety and similar weight. Adequate levels of phosphorus are necessary to ensure fruit firmness and avoid problems of fruit breakdown for example Low Temperature Breakdown (LTB).
Although calcium supply during fruit formation is important, other factors known to influence the final apple storage quality are:
- Rate of fruit growth. Fast growing fruit results in lower calcium levels.
- Crop loading. Light cropping trees tend to have low fruit calcium.
- Poor pollination giving low seed number if associated with low fruit calcium.
- Vigorous summer shoot growth competes for fruit nutrient supply
- Elevated magnesium, potassium and nitrogen levels can exacerbate marginal calcium status.
- Leaf area on fruiting spurs and laterals. Low leaf areas mean lower fruit calcium.
Taking a sample
- The fruit or fruitlet sampled must be representative of the crop in question.
- Avoid sampling from trees adjacent to shelterbelts, end of rows, replacement trees, pollinators or any abnormal area.
- 25 to 30 fruit or fruitlets per sample are recommended. These fruit or fruitlets should be taken one per tree.
- Fruitlets should be 20 – 35 g, up to 35 mm in diameter, or 100 mm circumference.
- Sample from various sides of the trees to help ensure the sample is representative.
- Collect fruit or fruitlets at shoulder height (1.5m).
- Avoid fruit or fruitlets showing any physical damage or disorders, unless this is characteristic of the crop.
- Avoid unusually large or small fruitlets. The sample should comprise fruitlets that would be expected to develop into average size export fruit.
- Any clean and sturdy plastic bag can be used to send in a sample and please label the sample bag clearly with a permanent marker pen.
- Print a Fruitlet Sample Analysis Request Form
Guides and supporting information
Freephone 0508 HILL LAB (44 555 22) or email Ag.CSM@hill-labs.co.nz