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Abstract
Normalized electrical impedance and cold hardiness were measured for internodal sections of ‘Delicious’ apple (Malus domestica Borkh.) during fall and winter for 2 years. Each year, the normalized impedance for the August date was significantly higher than on later dates. The relationship between normalized impedance and cold hardiness was inconsistent; r2=0.03 and P>5%, first year and r2=0.4 and P<1%, second year. The relationship between cold hardiness and the mean temperature for the 7 days before the sample date was consistent; r2=0.85 and P<1%, first year and r2=0.81 and P<1%, second year. The slope of the line relating sample diameter and normalized impedance changed from plus to minus each year.
Abstract
Normalized electrical impedance measured cold injury to stem sections of ‘Delicious’ apple (Malus domestica Borkh). The measurements did not alter later visual ratings of browning on the same sample. Normalized electrical impedance estimates of injury and visual ratings of browning agreed in 87% of the samples in the first year and 95% of the samples in the second year. In 29 of the 30 adjacent sampling temperatures that produced intermediate injury, as determined by visual browning, normalized impedance values had a higher probability of distinguishing between temperatures than did visual browning. Linear interpolation of the temperatures, which were needed to produce equal injury for the two methods, yielded a mean difference of 0.8°C.