EFFECTS OF RESPIRATION INHIBITORS ON ACCUMULATION OF RADIOACTIVE PHOSPHORUS BY ROOTS OF LOBLOLLY PINE

Abstract

No studies of this sort have been made on roots of woody species. A series of experiments was therefore performed to find whether or not respiration inhibitors reduce mineral accumulation in loblolly pine (Pinus taeda L.) roots as they do in barley roots. An attempt was also made to learn whether or not mycorrhizal roots react in the same manner as nonmycorrhizal roots. Since mycorrhizae represent a complex structure, consisting of both root tissue and fungal hyphae, it seemed possible that they might differ physiologically from those roots which have no fungus associated with them. Experiments with respiration inhibitors Roots were obtained from potted loblolly pine seedlings growing out of doors and from seedlings growing in a clearing in the forest. The root tips and segments bearing mycorrhizae were freed of foreign matter by gently brushing with a camel's hair brush in a shallow tray of distilled water. A total of 48 segments, each at least 2 cm. in length and bearing a healthy, growing tip, were selected and separated into four groups for the comparison of the various inhibitors. Since it was impossible to find 48 root tips of the same diameter, the tips were first divided into 12 groups, each containing four roots of approximately the same dimensions. One root from each group was then used in each treatment so the various sizes of roots were uniformly distributed among the four treatments. Roots bearing mycorrhizal branches were cut into segments 1 cm. in length and selected 30