CYTOCHROME AND ALTERNATE RESPIRATORY PATHWAY CAPACITIES OF PEACH EMBRYOS

Abstract

`Lovell' peach seeds were stratified for 0 to 12 weeks at 4°C under moist conditions. Differential Scanning Calorimetry (DSC) was used to study the respiratory capacity for the cytochrome (CP) and alternative (AP) pathway of the embryos during this period. Azide and SHAM titration curves were obtained by measuring the heat of metabolism produced by the excised embryos after vacuum infiltration with appropriate combinations of the two inhibitors.Uninhibited total respiratory activity increased steadily with the stratification treatment. AP capacity of the embryos was higher than CP capacity for the first 4 weeks of stratification. Between 4 and 6 weeks, CP capacity increased markedly and after 6 weeks was at least 40% higher than AP capacity. This rise on CP capacity coincided with the point at which an increase in seedling vigor and germinative capacity was observed and is in agreement with previous studies suggesting a change in respiratory efficiency as being responsible for the increase in seedling vigor.