268
GEORGE G. LATIES
ishes salt absorption (Honda, 1956; Robertson et al, 1951). (4) The
salt effect in many cases depends exclusively on the nature of the cation
(Steward and Preston, 1941; Handley and Overstreet, 1955). (5) The
salt respiration remains constant as the rate of accumulation declines
(Robertson and Turner, 1945).
There remains a possibility, in spite of what has just been said, that
the respiration may be stimulated by the act of salt transport. The evidence for this point of view derives primarily from the previously cited
work of Lundegárdh (1937; see also 1954, 1955a) which shows a direct
relation between the quantity of anion absorbed and the magnitude of
salt respiration evoked. Furthermore, both Lundegárdh (1937) and
Robertson and Wilkins (1948) have shown that the absorption of a
given quantity of chloride ion may be accompanied by the same level
of salt respiration whether the chloride is absorbed from salts of K+, Na+,
NH 4 +, Ca++, Mg++, Sr
f + , orBa++. Another piece of evidence that
the absorption process per se affects the respiration rate is offered in the
experiments of Hanson and Bonner (1954) in which it is shown that the
respiratory stimulations elicited by the processes of water uptake and
salt absorption are not additive. In view of the many questions which
may legitimately be raised regarding the significance of the salt-induced
respiration in different instances, the means by which neutral salts stimulate the respiration of a variety of tissues must remain moot.
The development of a respiratory increment upon aging, in slices from
tubers or tuberous roots, has been described previously. The increment
proved to be qualitatively distinct from at least part of the initial
respiration, and was presumably of a phosphorylative type. Evidence
from experiments on carrots and beets (Robertson et al., 1947), chicory
(Laties, 1954), and potatoes (Sharpensteen, 1953) indicates that the salt
respiration is dependent upon this phosphorylative type of respiration.
For example, neither carrot nor beet, when placed in dilute KCl within
five or six hours of cutting, show any salt respiration (Robertson et al.,
1947). After six hours, the response to salt increases with age until the
induced respiration is fully developed. The same situation obtains in
chicory (Laties, 1954, and in press). The ability of potato slices to
absorb phosphate also increases with age of the slices, and the effect of
dinitrophenol in abolishing phosphate absorption increases concomitantly
(Sharpensteen, 1953). Sutcliffe (1954) has reviewed the relationship of
aging to cation absorption in plant tissues.
In many tissues a respiratory component like the salt respiration is
not completely absent even in the absence of salt. Thus in barley roots
(Milthorpe and Robertson, 1948), wheat roots (Lundegárdh, 1953a), and
even in carrots (Robertson and Turner, 1945) and beets (Robertson et
GEORGE G. LATIES
ishes salt absorption (Honda, 1956; Robertson et al, 1951). (4) The
salt effect in many cases depends exclusively on the nature of the cation
(Steward and Preston, 1941; Handley and Overstreet, 1955). (5) The
salt respiration remains constant as the rate of accumulation declines
(Robertson and Turner, 1945).
There remains a possibility, in spite of what has just been said, that
the respiration may be stimulated by the act of salt transport. The evidence for this point of view derives primarily from the previously cited
work of Lundegárdh (1937; see also 1954, 1955a) which shows a direct
relation between the quantity of anion absorbed and the magnitude of
salt respiration evoked. Furthermore, both Lundegárdh (1937) and
Robertson and Wilkins (1948) have shown that the absorption of a
given quantity of chloride ion may be accompanied by the same level
of salt respiration whether the chloride is absorbed from salts of K+, Na+,
NH 4 +, Ca++, Mg++, Sr
f + , orBa++. Another piece of evidence that
the absorption process per se affects the respiration rate is offered in the
experiments of Hanson and Bonner (1954) in which it is shown that the
respiratory stimulations elicited by the processes of water uptake and
salt absorption are not additive. In view of the many questions which
may legitimately be raised regarding the significance of the salt-induced
respiration in different instances, the means by which neutral salts stimulate the respiration of a variety of tissues must remain moot.
The development of a respiratory increment upon aging, in slices from
tubers or tuberous roots, has been described previously. The increment
proved to be qualitatively distinct from at least part of the initial
respiration, and was presumably of a phosphorylative type. Evidence
from experiments on carrots and beets (Robertson et al., 1947), chicory
(Laties, 1954), and potatoes (Sharpensteen, 1953) indicates that the salt
respiration is dependent upon this phosphorylative type of respiration.
For example, neither carrot nor beet, when placed in dilute KCl within
five or six hours of cutting, show any salt respiration (Robertson et al.,
1947). After six hours, the response to salt increases with age until the
induced respiration is fully developed. The same situation obtains in
chicory (Laties, 1954, and in press). The ability of potato slices to
absorb phosphate also increases with age of the slices, and the effect of
dinitrophenol in abolishing phosphate absorption increases concomitantly
(Sharpensteen, 1953). Sutcliffe (1954) has reviewed the relationship of
aging to cation absorption in plant tissues.
In many tissues a respiratory component like the salt respiration is
not completely absent even in the absence of salt. Thus in barley roots
(Milthorpe and Robertson, 1948), wheat roots (Lundegárdh, 1953a), and
even in carrots (Robertson and Turner, 1945) and beets (Robertson et