1021-4437/03/5006- $25.00 © 2003
Russian Journal of Plant Physiology, Vol. 50, No. 6, 2003, pp. 835–842. Translated from Fiziologiya Rastenii, Vol. 50, No. 6, 2003, pp. 930–937.
Original Russian Text Copyright © 2003 by Veselova, Veselovskii, Usmanov, Usmanova, Kozar’.
The quality of seeds declines during their storage.
Germination of aged seeds gives rise to normal seed-
lings and abnormal seedlings with morphological
defects. In addition, in some alive seeds no radicle pro-
trusion occurred like in the dead seeds . During ger-
mination, seeds are particularly sensitive to environ-
mental factors; thus, the germinability depends largely
on the external conditions during the imbibition [2–4].
The aged seeds are more susceptible to damage during
imbibition as compared to freshly harvested seeds [3–9].
The rapid entry of water into a dry seed may damage
the cells mechanically. The water inﬂow into the cells
of dry embryo disrupts their membranes, thereby caus-
ing the leakage of ions, proteins, carbohydrates, and
other substances [5, 7, 10]. Upon the submergence of
seeds, some cells died within few minutes or even sec-
onds [5, 6, 11].
Hypoxia is another injuring factor developing dur-
ing the imbibition of legume seeds . Hypoxia usually
arises when the imbibition proceeds under the excess of
water in the ambient medium. The most likely cause of
hypoxia is rapid oxygen consumption by the seed
embryo and slow oxygen diffusion into the seed through
the seed coat; the seed coat is known to restrict the supply
of atmospheric oxygen to the embryo [5, 12–14].
Based on the seed by seed measurements of room
temperature phosphorescence (RTP), we separated a lot
of air-dry aged seeds into three fractions [15, 16]. The
fraction-I seeds produced normal seedlings. The frac-
tion-II viable seeds either gave rise to abnormal seed-
lings or were unable to germinate at all. The fraction III
consisted of dead seeds. The RTP method allowed us to
characterize individual fractions of aging seeds rather
than averaged parameters of unsorted seed lot.
We characterized here the imbibition patterns for
aging seeds of different quality and attempted to eluci-
Hypoxia and Imbibition Injuries to Aging Seeds
T. V. Veselova*, V. A. Veselovskii*, P. D. Usmanov
**, O. V. Usmanova**, and V. I. Kozar’*
*Biophysics Department, Faculty of Biology, Moscow State University, Vorob’evy gory, Moscow, 119899 Russia;
**Institute of Plant Physiology and Genetics, National Academy of Sciences of Tajikistan, Dushanbe, 734063 Tajikistan
Received October 23, 2002
—The development of hypoxia and primary injuries were examined during the imbibition of aging
pea seeds (
L., cv. Nemchinovskii). The distribution of air-dry pea seeds by their room-temper-
ature phosphorescence revealed the presence of two fractions (I and II) in a seed lot with 72% germinability
and three fractions (I, II, and III) in a seed lot with 50% germinability. The water uptake during imbibition was
slower in the fraction I seeds than in the fraction-II seeds. The fraction-I seeds produced normal seedlings,
whereas the fraction-II seeds either produced seedlings with morphological defects (abnormal) or did not ger-
minate at all. The fraction-III seeds were all dead. The phosphorescence of endogenous porphyrins, emitted
only at low O
content, was measured after 20-h seed imbibition. The fraction-I seeds emitted no discernible
phosphorescence. The fraction-II comprised highly phosphorescent seeds incapable of radicle protrusion and
moderately phosphorescent seeds producing abnormal seedlings. The fraction-II seeds experienced hypoxia
during the imbibition because of rapid oxygen consumption by the embryo and restrictions to O
imposed by the seed coat. In the fraction-I seeds, the rate of oxygen consumption by the embryo was slower
and the seed coat resistance to oxygen diffusion was lower than in the fraction-II seeds. Therefore, hypoxia did
not arise in the fraction-I seeds. The submergence of seeds in water caused lethal injuries. The imbibition of
seeds without any contact with water caused no lethal damages but did not reduce the percentage of seeds dying
of hypoxia. A slow imbibition of seeds in the media containing either an osmoticum (PEG) or an inhibitor of
aquaporin channels (
-chloromercuribenzoate) prevented the lethal injuries at early stages of seed hydration
and retarded the appearance of oxygen deﬁciency in fraction-II seeds. Different rates of water uptake by frac-
tion-I and fraction-II seeds were controlled by permeability of cell membranes rather than by permeability of
seed coat. It is proposed that low permeability of plasma membranes to water in fraction-I seeds results from
the predominantly closed aquaporin channels, whereas a higher permeability of weak seeds (fraction II) is due
to open channels.
Key words: Pisum sativum - natural aging - seeds - seed lot fractions - primary injuries during imbibition -
hypoxia - phosphorescence of endogenous porphyrins - aquaporin channels
humidity; RTP—room temperature phosphorescence.