Preliminary results on IAD Maturity classes for selected Stonefruit

CultivarSeasonalityImmature
(no ethylene,
not to be
harvested)
Harvest Ready
(on-set climacteric,
suitable for export
and domestic)
Mature
(climacteric peak,
suitable
for domestic)
Golden MayApricot - Mid> 1.201.19 - 0.60< 0.59
AngelenoPlum - Late> 1.301.29 - 1.0< 0.99
Snow Flame 23Peach - Early> 0.90.90 - 0.30< 0.3
Snow Flame 25Peach - Mid> 1.01.0 - 0.60< 0.6
Rose BrightNectarine - Early> 1.01.0 - 0.40< 0.40
Majestic PearlNectarine - Mid> 1.21.19 - 0.5< 0.49
Summer BrightNectarine - Mid> 0.700.69 - 0.30< 0.29
Fire SweetNectarine - Mid> 1.00.99 - 0.50< 0.49
Summer Flare 26Nectarine - Mid> 1.00.99 - 0.60< 0.59
Summer Flare 34Nectarine - Mid> 1.201.19 - 0.60< 0.59
August FireNectarine - Late> 1.00.99 - 0.50< 0.49
Autumn BrightNectarine - Late> 1.01.0 - 0.60< 0.60
August BrightNectarine - Late> 0.900.90 - 0.40< 0.40
September RedNectarine - Late> 1.101.09 - 0.60< 0.59
September BrightNectarine - Late> 1.201.20 - 0.50< 0.50
August FlamePeach - Late> 1.301.30 - 0.70< 0.70
September SunPeach - Late> 1.201.20 - 0.80< 0.80
Ice PrincessPeach - Mid > 1.301.30 - 0.50< 0.50
O'HenryPeach - Early> 0.900.90 - 0.60< 0.60
O'HenryPeach - Late> 1.201.20 - 0.70< 0.70
Red HavenPeach - Mid> 1.601.60 - 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.