Differential Sensitivity to Waterlogging and Cyanogenesis by Peach, Apricot, and Plum Roots1

Abstract

Individual plants varied considerably, but peach and apricot were more sensitive to waterlogging than was plum. No differences were established between peach and apricot. All 3 species became more sensitive as temperature was increased between 17 and 27°C. More than half of the plum seedlings survived at 17°C whereas all plants of the other 2 species died. A scion of a more tolerant species did not overcome the sensitivity of the roots. Both cyanogenic glycoside content and the proportion of it that was hydrolyzed during waterlogging were higher in peach than in plum roots. Exposure of detached root systems of all 3 species to anaerobic conditions caused HCN to be released. The rate of cyanogenesis increased with both temperature and time. Peach and apricot roots were alike in HCN evolution whereas plum roots were lower, with release of HCN being barely detectable at 22°C. Cyanogenesis was significant in peach and apricot at as low as 17°C. A close association exists among differential sensitivity, glycoside hydrolysis, and cyanogenesis in the absence of O2. However, the latter may be secondary, though contributory, to cellular disorganization as a cause of sensitivity.

Differential Sensitivity of Juglans hindsii, J. regia, Paradox Hybrid, and Pterocarya stenoptera to Waterlogging1

“…It is not suggested that the release of phenolics is a primary phenomenon involved in sensitivity to waterlogging. Initial effects would seem to be those already proposed (10) in that anaerobiosis inhibits production and transfer of energy required for maintenance of membranes. Support for the involvement of the respiratory mechanism as a primary influence in sensitivity is gained by the proposal that metabolic pathways shift to production of ethanol during anaerobiosis (4).…”

“…Sensitivity to waterlogging is temperature dependent (1). Differences in sensitivity among Prunus species found at lower temperatures were not as evident at higher ones (10). Thus, seedlings of the 2 walnut species and Paradox plants were waterlogged at a lower temperature, 23°C, to determine if a difference between them could be resolved.…”

“…Root cells have been shown to release their contents during anaerobiosis (6). Loss of selective permeability of membranes was thought to lead to hydrolysis of cyanogenic glycosides with resultant HCN contributing to sensitivity of Prunus to waterlogging (10). Although walnut does not contain cyano genic glycosides (unpublished), release of vacuolar phenolic compounds would be expected to be inhibitory to cellular metabolism through complexing with and denaturation of proteins.…”

“…Earlier work with Prunus species employed a testing pro cedure which allowed rapid, objective determination of sen sitivity to waterlogging (10). Paradox plants (/.…”

The Ecology of Tree Roots and the Practical Significance Thereof

“…Other species, particularly cherries and other members of the rose family, are especially sensitive to conditions where oxygen supplies are limiting. Cherry roots contain cyanophoric glucosides, which are hydrolized to form cyanide when oxygen supplies are limiting (Rowe and Catlin 1971). Flooding of less than 24 hours killed most of the Japanese cherry trees around Hains Point in Washington, D.C. after hurricane Agnes in 1973.…”