Apricots for Asia 2021, a project funded by Summerfruit NZ and AGMARDT, has been underway this season looking into the new Nzsummer series of apricots out of the Summerfruit NZ/Plant & Food Research breeding programme in Clyde. The project is multifaceted, including maturity sampling, postharvest storage and a simulated supply chain aspect. It also includes a first look at how these new cultivars respond to ethylene and whether 1-MCP treatment is a viable option to slow the ripening process by inhibiting ethylene production. Unwanted ethylene may arise within the supply chain if stored with other produce. Finally, if the situation allows, there will be an export shipment for three of the five cultivars being evaluated.
Figure 1: Various ‘Nzsummer2’ fruit at harvest for harvest maturity monitoring.
Getting the harvest maturity of these new cultivars right is critical for optimal storage and eating experience. This project aims to understand the best harvest window for a desirable outcome for each new cultivar and develop protocols to help growers determine when the crop has reached this stage. We already know that some of these cultivars behave differently from existing apricot cultivars. Without appropriate sampling and knowledge, there is a tendency to harvest earlier than is desirable for the best eating experience by consumers.
Fruit from each cultivar are being harvested at four to seven day intervals at sites around Central Otago and Hawke’s Bay where available, starting approximately one week prior to the main harvest date, estimated by the growing degree days (GDD) accumulated by mid-December.
Based on the previous year’s harvests in Clyde, early GDD were used to estimate first harvest timing of each cultivar and have so far proved a useful way of predicting maturity timing in the new cultivars. For example, with ‘Nzsummer2’, six years of harvest data have a strong correlation with GDD at 15 December. We estimated that the fruit would be harvested around 28 January this season, and this was accurate ±two days.
Fruit sampled at each harvest are then being run through a packing line, and a subsample assessed immediately for firmness, sugar, acid and taste. The remaining fruit are being stored for up to six weeks with weekly sampling. This will enable us to determine the best harvest timing for optimal storage that ensures they will perform in an export supply chain.
In addition, trays of fruit from a single site will be put through a simulated supply chain with short term ‘kill zone’ temperature storage followed by 20˚C shelf life for up to eight days. This work aims to understand how the harvest timing affects fruit in a simulated ‘pick, pack, fly’ supply chain. Harvest timing for this scenario may be different to that recommended for longer storage scenarios.
Work in Hawke’s Bay will also introduce ethylene to see if these new cultivars will stand up to the conditions when stored with other produce such as apples, and if they will respond positively to
1-MCP treatment.
To tie the project together, and test the theory in a real-world scenario, small shipments of each of the three cultivars, where possible, will be sent to offshore markets to evaluate fruit condition on arrival and for instore consumer feedback.
Early harvest results are being collated and compared against the industry standard ‘Clutha Gold’ where we will begin to see differences in quality attributes to determine optimal harvest timing. For example, using average °Brix measurements at each harvest as seen in the graph below.
Figure 2: Average soluble solids concentrations at each harvest timing of ‘Nzsummer2’ and ‘Clutha Gold’ in Roxburgh, Central Otago.
Our harvest and postharvest data will be analysed, and recommendations developed. These will be presented at a grower workshop or conference and the new variety release information booklet will be updated.
For more information, please contact Claire Scofield or Jill Stanley.