Grape berry respiration: Effects of metabolic inhibitors

Abstract

The rate of O2 uptake, respiratory quotient and the effects of metabolic inhibitors on respiration were followed throughout berry development of 4 varieties of Vitis vinifera L. No obvious differences in respiratory characteristics were found between seeded and seedless and between pigmented and nonpigmented grapes. Physiological differences between immature and maturing grape berries involve altered rates of respiration and a changed sensitivity to metabolic inhibitors. With development in all varieties there was a decline in O2 uptake on a fresh weight basis while R.Q. values rose to greater than unity. Dinitrophenol failed to stimulate O, uptake at any stage and the inhibition of O2 uptake caused by azide or DNP was more severe in mature fruit than in immature fruit. Cyanide stimulated O2 uptake in tissue slices from immature Sultana berries but inhibited O2 uptake in slices from more developed fruit. These data, coupled with the absence of any major alteration in the level of insoluble nitrogen per unit fresh weight of berry suggest that respiration is both quantitatively and qualitatively different in immature compared with maturing grape berries.