Preliminary results on IAD Maturity classes for selected Stonefruit
| Cultivar | Seasonality | Immature (no ethylene, not to be harvested) | Harvest Ready (on-set climacteric, suitable for export and domestic) | Mature (climacteric peak, suitable for domestic) |
|---|---|---|---|---|
| Golden May | Apricot - Mid | > 1.20 | 1.19 - 0.60 | < 0.59 |
| Angeleno | Plum - Late | > 1.30 | 1.29 - 1.0 | < 0.99 |
| Rose Bright | Nectarine - Early | > 1.0 | 1.0 - 0.40 | < 0.40 |
| Snow Flame 23 | Peach - Early | > 0.9 | 0.90 - 0.30 | < 0.3 |
| Snow Flame 25 | Peach - Mid | > 1.0 | 1.0 - 0.60 | < 0.6 |
| Summer Bright | Nectarine - Mid | > 0.70 | 0.69 - 0.30 | < 0.29 |
| Fire Sweet | Nectarine - Mid | > 1.0 | 0.99 - 0.50 | < 0.49 |
| Summer Flare 26 | Nectarine - Mid | > 1.0 | 0.99 - 0.60 | < 0.59 |
| Summer Flare 34 | Nectarine - Mid | > 1.20 | 1.19 - 0.60 | < 0.59 |
| August Fire | Nectarine - Late | > 1.0 | 0.99 - 0.50 | < 0.49 |
| Autumn Bright | Nectarine - Late | > 1.0 | 1.0 - 0.60 | < 0.60 |
| August Bright | Nectarine - Late | > 0.90 | 0.90 - 0.40 | < 0.40 |
| September Red | Nectarine - Late | > 1.10 | 1.09 - 0.60 | < 0.59 |
| September Bright | Nectarine - Late | > 1.20 | 1.20 - 0.50 | < 0.50 |
| August Flame | Peach - Late | > 1.30 | 1.30 - 0.70 | < 0.70 |
| September Sun | Peach - Late | > 1.20 | 1.20 - 0.80 | < 0.80 |
| Ice Princess | Peach - Mid | > 1.30 | 1.30 - 0.50 | < 0.50 |
| O'Henry | Peach - Early | > 0.90 | 0.90 - 0.60 | < 0.60 |
| O'Henry | Peach - Late | > 1.20 | 1.20 - 0.70 | < 0.70 |
| Red Haven | Peach - Mid | > 1.60 | 1.60 - 0.60 | < 0.60 |
IAD and the DA meter
The DA meter measures the flesh greenness by reflectance of two wavelengths (670 and 720 nm) of light, near the chlorophyll-a absorbance peak. The reflectance is expressed as an index of absorption difference (IAD) scaled from 0 to 3 (green). Comparison of IAD with fruit ethylene production for many cultivars has shown a strong inverse relationship supporting the DA meter as a tool to measure fruit maturity.