A field study on the respiration rates in the leaves of temperate plants

Abstract

The field respiration rates of leaves, in terms of total dark respiration, cytochrome (cyanide sensitive) pathway respiration, and alternative (salicylhydroxamic acid sensitive) pathway respiration, were measured in 10 temperate species. Five spring understory herbs and five ruderal species were used. All species displayed resistance to cyanide and sensitivity to salicylhydroxamic acid, indicating a capacity and some engagement of the alternative pathway. In comparison with reports on the field respiration rates of leaves in arctic and boreal species, the temperate plants had significantly less O2 uptake along both respiratory pathways. Rates of alternative pathway respiration in this study were comparable with those reported in the leaves of crop plants. In a comparison of respiration rates between the ruderal and understory species, the ruderal species had significantly greater activity along the alternative pathway. The ruderals also had a significantly greater capacity for the alternative pathway. It is proposed that the presence of the alternative pathway somehow allows physiological flexibility in the ruderals, and this in turn aids in their survival in fluctuating environments. Key words: alternative pathway, cyanide resistance, respiration, ruderal, understory.