Apple Fruitlet Analysis - A powerful tool for quality
Latest research is now clearly indicating that early season fruitlet analysis can be a good indicator to mineral composition of fruit at harvest and the eventual storage potential of the fruit. Phosyn, international specialists in crop nutrition, have been investing in the research of fruitlet analysis in New Zealand fruit since 1993 and in the last three seasons have considerably stepped up this research.
When mineral deficiencies or imbalances occur, fruit may be susceptible to bitter pit, scald, poor firmness and senescent or low temperature breakdown. These quality issues affect the storage potential of fruit and limit the profitability of production.
One of the problems with the present practice of pre-harvest analysis is that at this stage it is too late to react to the findings of the analysis. If the result shows a low level of calcium or phosphorus, the best the grower can do is try to manage the marketing of the fruit so it is sold first and better quality fruit is held until later. Then improve these levels with good mineral inputs the following season.
The ability to predict storage potential and shelf quality from mineral analysis at an early stage in crop growth would be of enormous benefit to growers. The information would enable them to adjust nutritional levels and inputs during the season and make more informed judgements about the storage potential of their fruit. Phosyn has achieved this with the development of Megalab and the early season fruitlet analysis, which allows the grower to analyse his fruit from 30 grams and receive advance warning of any potential nutritional imbalances.
Megalab - a unique database
Megalab is a unique database of information using the results of many thousands of analysis of different apple varieties from New Zealand and around the world, dating back to 1993. Statistical or biometric analysis of the information in the database shows how the nutrient levels change in the apple as the season progresses and the fruit gets larger. For example, calcium in New Zealand apples is giving a correlation coefficient or r2 of 0.78, which means that 78% of the change in calcium concentration is explained by the increase in fruit weight. (See Graph: 1) This now enables the probability of nutrient deficiencies and imbalances occurring in the fruit at harvest to be predicted, with a high degree of accuracy, from the nutrient level in the fruitlet.
The large amount of information built up in the New Zealand database can give separate information for Braeburn, Cox and other varieties.
New Zealand information can easily be filtered from the international database and results can be looked at on a national basis or filtered again to different districts, growers and individual blocks.
The database continues to evolve with new information being added constantly to further enhance the accuracy of the predictions of probability.
The apple fruitlet samples are analysed at Hill Laboratories and the analysis result, along with the accompanying grower ID, orchard ID and fruit information is e-mailed into the Megalab computer database. The grower quickly receives a free Megalab Interpretation Analysis Report telling him how each nutrient is tracking and giving recommendations if necessary. Also, where high nutrient levels of some minerals are recorded, growers could cut back on inputs to give further cost savings.
Different calcium formulations
The information is indicating that in some situations different product formulations, than have traditionally been used, would be of benefit to fruit and to general tree health. For example, nitrogen in New Zealand fruit has generally been considered to be adequate or high, however, the database is showing that in some instances nitrogen is below the recommended guideline level. Trees with low nitrogen could suffer poor leaf quality and vigour. Also fruit could be small and taste quality could be affected. Stopit N, a formulated liquid calcium nitrate, has been introduced to the New Zealand market and will be recommended to growers where their Megalab report indicates there would be a benefit. (See Graph: 2) Fruit with adequate or high nitrogen would be recommended Stopit, a formulated liquid calcium chloride, proven for its crop safety and performance.
Analysis and a Megalab report becomes very important, as calcium nitrate applied to fruit with high nitrogen could be very detrimental, resulting in fruit which could be of poor colour and have poor storage potential. Fruit with adequate to high nitrogen would receive a Megalab report recommending Stopit, a formulated calcium chloride with proven crop safety.
Stopit N has been used on high russet risk varieties with excellent results and Phosyn´s own research has shown it to be as safe as Stopit, even when used at high rates. The 6-week period after petal fall fruit is very sensitive to russetting so it is important to only use products that are proven and known to be safe.
Author: Michael Waites, New Zealand
Published: October 2000