A Fruit Colour Development Index (CDI) to Support Harvest Time Decisions in Peach and Nectarine Orchards
Fruit skin colour is one of the most important visual fruit quality parameters driving consumer preferences. Proximal sensors such as machine vision cameras can be used to detect skin colour in fruit visible in collected images, but their accuracy in variable orchard light conditions remains a pract...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-05-01
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| Series: | Horticulturae |
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| Online Access: | https://www.mdpi.com/2311-7524/8/5/459 |
| _version_ | 1797499406739570688 |
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| author | Alessio Scalisi Mark G. O’Connell Muhammad S. Islam Ian Goodwin |
| author_facet | Alessio Scalisi Mark G. O’Connell Muhammad S. Islam Ian Goodwin |
| author_sort | Alessio Scalisi |
| collection | DOAJ |
| description | Fruit skin colour is one of the most important visual fruit quality parameters driving consumer preferences. Proximal sensors such as machine vision cameras can be used to detect skin colour in fruit visible in collected images, but their accuracy in variable orchard light conditions remains a practical challenge. This work aimed to derive a new fruit skin colour attribute—namely a Colour Development Index (CDI), ranging from 0 to 1, that intuitively increases as fruit becomes redder—to assess colour development in peach and nectarine fruit skin. CDI measurements were generated from high-resolution images collected on both east and west sides of the canopies of three peach and one nectarine cultivars using the commercial mobile platform <i>Cartographer</i> (Green Atlas). Fruit colour (RGB values) was extracted from the central pixels of detected fruit and converted into a CDI. The repeatability of CDI measurements under different light environments was tested by scanning orchards at different times of the day. The effects of cultivar and canopy side on CDI were also determined. CDI data was related to the index of absorbance difference (I<sub>AD</sub>)—an index of chlorophyll degradation that was correlated with ethylene emission—and its response to time from harvest was modelled. The CDI was only significantly altered when measurements were taken in the middle of the morning or in the middle of the afternoon, when the presence of the sun in the image caused significant alteration of the image brightness. The CDI was tightly related to I<sub>AD</sub>, and CDI values plateaued (0.833 ± 0.009) at I<sub>AD</sub> ≤ 1.20 (climacteric onset) in ‘Majestic Pearl’ nectarine, suggesting that CDI thresholds show potential to be used for harvest time decisions and to support logistics. In order to obtain comparable CDI datasets to study colour development or forecast harvest time, it is recommended to scan peach and nectarine orchards at night, in the early morning, solar noon, or late afternoon. This study found that the CDI can serve as a standardised and objective skin colour index for peaches and nectarines. |
| first_indexed | 2024-03-10T03:46:54Z |
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| id | doaj.art-f4c4bf70ec5b49db85a73df777abb874 |
| institution | Directory Open Access Journal |
| issn | 2311-7524 |
| language | English |
| last_indexed | 2024-03-10T03:46:54Z |
| publishDate | 2022-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Horticulturae |
| spelling | doaj.art-f4c4bf70ec5b49db85a73df777abb8742023-11-23T11:17:39ZengMDPI AGHorticulturae2311-75242022-05-018545910.3390/horticulturae8050459A Fruit Colour Development Index (CDI) to Support Harvest Time Decisions in Peach and Nectarine OrchardsAlessio Scalisi0Mark G. O’Connell1Muhammad S. Islam2Ian Goodwin3Tatura SmartFarm, Agriculture Victoria, Tatura, VIC 3616, AustraliaTatura SmartFarm, Agriculture Victoria, Tatura, VIC 3616, AustraliaTatura SmartFarm, Agriculture Victoria, Tatura, VIC 3616, AustraliaTatura SmartFarm, Agriculture Victoria, Tatura, VIC 3616, AustraliaFruit skin colour is one of the most important visual fruit quality parameters driving consumer preferences. Proximal sensors such as machine vision cameras can be used to detect skin colour in fruit visible in collected images, but their accuracy in variable orchard light conditions remains a practical challenge. This work aimed to derive a new fruit skin colour attribute—namely a Colour Development Index (CDI), ranging from 0 to 1, that intuitively increases as fruit becomes redder—to assess colour development in peach and nectarine fruit skin. CDI measurements were generated from high-resolution images collected on both east and west sides of the canopies of three peach and one nectarine cultivars using the commercial mobile platform <i>Cartographer</i> (Green Atlas). Fruit colour (RGB values) was extracted from the central pixels of detected fruit and converted into a CDI. The repeatability of CDI measurements under different light environments was tested by scanning orchards at different times of the day. The effects of cultivar and canopy side on CDI were also determined. CDI data was related to the index of absorbance difference (I<sub>AD</sub>)—an index of chlorophyll degradation that was correlated with ethylene emission—and its response to time from harvest was modelled. The CDI was only significantly altered when measurements were taken in the middle of the morning or in the middle of the afternoon, when the presence of the sun in the image caused significant alteration of the image brightness. The CDI was tightly related to I<sub>AD</sub>, and CDI values plateaued (0.833 ± 0.009) at I<sub>AD</sub> ≤ 1.20 (climacteric onset) in ‘Majestic Pearl’ nectarine, suggesting that CDI thresholds show potential to be used for harvest time decisions and to support logistics. In order to obtain comparable CDI datasets to study colour development or forecast harvest time, it is recommended to scan peach and nectarine orchards at night, in the early morning, solar noon, or late afternoon. This study found that the CDI can serve as a standardised and objective skin colour index for peaches and nectarines.https://www.mdpi.com/2311-7524/8/5/459machine visionmaturitymeasurement timeorchard automationprecision horticultureproximal sensing |
| spellingShingle | Alessio Scalisi Mark G. O’Connell Muhammad S. Islam Ian Goodwin A Fruit Colour Development Index (CDI) to Support Harvest Time Decisions in Peach and Nectarine Orchards Horticulturae machine vision maturity measurement time orchard automation precision horticulture proximal sensing |
| title | A Fruit Colour Development Index (CDI) to Support Harvest Time Decisions in Peach and Nectarine Orchards |
| title_full | A Fruit Colour Development Index (CDI) to Support Harvest Time Decisions in Peach and Nectarine Orchards |
| title_fullStr | A Fruit Colour Development Index (CDI) to Support Harvest Time Decisions in Peach and Nectarine Orchards |
| title_full_unstemmed | A Fruit Colour Development Index (CDI) to Support Harvest Time Decisions in Peach and Nectarine Orchards |
| title_short | A Fruit Colour Development Index (CDI) to Support Harvest Time Decisions in Peach and Nectarine Orchards |
| title_sort | fruit colour development index cdi to support harvest time decisions in peach and nectarine orchards |
| topic | machine vision maturity measurement time orchard automation precision horticulture proximal sensing |
| url | https://www.mdpi.com/2311-7524/8/5/459 |
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