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UDC 633.854.78:631.53.01.026:631.542.841
DOI: 10.2298/HEL1052153B
SEED VIABILITY OF OIL CROPS DEPENDING ON
STORAGE CONDITIONS
Balešević-Tubić, S.
*
, Tatić, M., Ðorđević, V., Nikolić, Z. and Ðukić, V.
Institute of Field and Vegetable Crops, M. Gorkog 30, 21000 Novi Sad,
Republic of Serbia
Received: July 01, 2009
Accepted: April 03, 2010
SUMMARY
Changes occurring in seed during aging are significant as far as seed quality
and longevity are concerned and are a consequence of the effects of different stor-
age conditions. The chemical composition of seed with high oil content is related
to specific processes occurring in seed during storage. In this trial, sunflower
and soybean genotypes developed in Novi Sad were submitted to accelerated
aging for three and five days, and natural aging for six and twelve months,
under controlled and conventional (non-controlled) conditions. The obtained
results showed that preservation of seed viability depended on storage condi-
tion and duration, as well as plant species. Accelerated aging test can be used
to predict the length of storage life of sunflower and soybean seed. In compari-
son to sunflower seed, soybean seed is more sensitive to damage and reduced
germination during storage.
Key words: sunflower, soybean, seed, aging, germination
INTRODUCTION
Changes that occur in seed during aging are significant in terms of seed quality,
the feature that, among other things, also implies seed longevity (Milošević and
Malešević, 2004). Progress of the technology and industrialization of agricultural
production has increased opportunities for long term storage of seed (Lekić, 2003).
The purpose of storage is to maintain harvest quality of product, not to improve it
(Sisman and Delibas, 2004). The rate at which the seed aging process takes place
depends on the ability of seed to resist degradation changes by protection mecha-
nisms which are specific for each plant species (Balešević-Tubić, 2001). Kept under
the same storage conditions, seeds of different plant species lose viability to a vari-
ous degree. For example, onion seed is very difficult to store, while barley seed
maintains good germination under a variety of storage conditions (Milošević et al.,
1996). The chemical composition of oilseeds causes specific processes to occur
* Corresponding author: e-mail: svetlanabt@ifvcns.ns.ac.rs
154 HELIA, 33, Nr. 52, p.p. 153-160, (2010)
during storage. The seeds rich in lipids have limited longevity due to their specific
chemical composition. For example, sunflower seed storage demands special atten-
tion due to high oil content, otherwise processes may occur that lead to loss of ger-
mination ability and seed viability (Christensen, 1971; Balešević-Tubić et al., 1999;
Balešević-Tubić et al., 2007a).
Some researchers believe that survival of plants in adverse field conditions can
be reliably predicted on the basis of laboratory germination tests. Others maintain
that small differences in germination percentage can sometimes overshadow large
differences existing in seed damage rate (Milošević and Ćirović, 1994). The same
authors suggested that under adverse conditions such as the temperature above
30°C and relative air humidity from 80 to 90% the variation in seed germination
rate can be high. It seems that temperature, moisture and storage duration are the
most important individual factors which affect on stored product quality and quan-
tity (Sisman, 2005).
Accelerated aging of seed, i.e., seed lot exposure to high temperature and high
relative humidity leads to a loss of vigor and eventually to a loss of viability. It is an
excellent method for determination of changes in vigor during seed storage (Tian et
al., 2008). An accelerated aging test showed that the aging seed is characterized by
the loss of germination, reduced germination rate and poor seedling development
(Lekić, 2003; Tatić et al., 2008). Fabrizius et al. (1999) confirmed the possibility of
predicting the actual germination rate of soybean seed during natural aging by
applying the accelerated aging test, the main factors being the time of natural aging
duration and degree of seed deterioration.
The objectives of this study were to determine how different seed storage meth-
ods and storage times affected the germinability of diferent oil crops and to examine
the possibility of using the accelerated aging test for the assessment of reduced or
preserved seed viability over time.
MATERIALS AND METHODS
The seed of five sunflower lines and six soybean varieties developed at Institute
of Field and Vegetable Crops, Novi Sad, was submitted to accelerated and natural
aging.
Accelerated aging. The seed was placed in metal dishes, on metal sieves
immersed in a water bath at 42°C and relative humidity of 100%. The test lasted
three and five days.
Natural aging. Seed was stored in two ways. One part was kept in a cool cham-
ber (controlled conditions), at 4°C and relative air humidity of 80 to 85%, another
was kept under conventional storage conditions (non-controlled conditions). Seed
characteristics were tested after six and 12 months of storage.
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Germination of fresh and artificially and naturally aged seed was estimated by
the standard laboratory germination test, according to the Rules of International
Seed Testing Association (ISTA, 1999). The results of the treated seed were com-
pared with the germinability of fresh seeds (measured at the start of the experiment
and used as the control treatment).
Statistical analysis. Mean comparison (t-test) and simple linear regression
tests were done using the statistical software Statisica8. All values represented in
this paper are averages over four replications.
RESULTS AND DISCUSSION
Concerning the duration of storage, reduced germination was observed in all
sunflower genotypes, which was particularly significant after 12 months of storage
(Figure 1). The above-mentioned results revealed that some changes leading to
decreased germination occurred also during natural sunflower seed aging. It is
worth mentioning that the seed germination of the tested sunflower lines declined
more in the seed stored under conventional conditions than that stored under con-
trolled conditions. Changes leading to decreased germination occurred in sunflower
seed during storage under conventional conditions due to high oil content (Beratlief
and Iliesku, 1997). These authors stated that optimal conditions for sunflower seed
storage and effective prevention of seed deterioration were a temperature below
10°C, and a relative air humidity up to 70%. According to Ghasemnezhad and Hon-
ermeir (2007), the storage life of sunflower seed can be reduced by long storage
and high storage temperature.
F
igure 1: Changes in seed germination of sunflower and soybean genotypes under differ-
ent storage conditions and duration (FS-fresh seed; CC-controlled conditions and
CS-conventional storage, measured after 6 and 12 months)
156 HELIA, 33, Nr. 52, p.p. 153-160, (2010)
It is important to note that the seed germination of the studied soybean geno-
types declined more in the seeds stored under conventional conditions, due to vari-
ability in temperature and relative humidity (Figure 1), than in the seeds stored
under controlled conditions. The results provided futher proof that, in addition to
cultivar, storage conditions, and duration were significant factors affecting the ger-
mination rate of soybean seed. Similar results were obtained by Nugraha and Soe-
jadi (1991) for soybean seed stored for six months under conventional conditions.
They stated that in a group of tested varieties only one maintained germination
above 80%.
The tested sunflower and soybean genotypes had similar initial seed germina-
tion rates, 90 and 89.7%, respectively. However, decline in seed germination after
six and twelve months of storage was more pronounced in the soybean genotypes,
especially under conventional conditions (by 14.1% and 36.4%, respectively), than
in the sunflower genotypes. The obtained results indicated that the soybean seed
was significantly more sensitive to the length of storage, as well as to storage condi-
tions, than the sunflower seed.
Sunflower seed was much more stable in terms of
storage duration, and the decrease in germination rate after 12 months of storage
was approximately equal to the decrease in germination rate of soybean genotypes
after six months of storage, both under controlled
(81.6% for sunflower germina-
tion, 81.0% for soybean germination, respectively), and under conventional condi-
tions (78.2% for sunflower germination, 76.8% for soybean germination,
respcetively).
Different longevity of seed storage as well as storage conditions exert significant
influence on seed germination (Nkang and Umoh, 1997). The results of Sharma
(1977) clearly pointed out to declining trends in total oil content and seed germina-
tion during storage of oilseed species. Seed aging during storage is an inevitable
phenomenon, but the degree and speed of decline in seed quality depend strongly,
beside storage conditions, on plant species stored and initial seed quality (Elias and
Copeland, 1994; Balešević-Tubić et al., 2005) as well as on seed genetic traits
(Malenčić et al., 2003). Milošević et al. (1996) suggested too that seed longevity is
genetically determined, and that significant differences exist among cultivars of the
same crop in their ability of quality maintenance during storage. Therefore, they
suggested that the longevity of seed can be improved by appropriate breeding proce-
dures.
Artificial aging of sunflower and soybean seed cause a significant reduction in
the seed germination rate. Seed germination of the sunflower lines submitted to
accelerated aging for three days (Figure 2) was approximately equal to the seed ger-
mination rate measured after 12 months of natural aging (R
2
=0.93), while in soy-
bean genotypes a high similarity existed in seed germination rates after five days of
artificial aging and seed storage for 12 months under conventional conditions
(R
2
=0.92). A comparison of germination rate decline after artificial aging and stor-
age under conventional conditions revealed that the sunflower seed was more
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resistant to stress conditions than the soybean seed. The soybean seed subjected to
extreme conditions of accelerated aging for five days suffered stress that was com-
parable to that suffered by 12 monhts of natural aging. This indicates that, in soy-
bean seed, adverse processes were more intensive, and that it why it was more
difficult to store soybean seed than sunflower seed. The obtained results confirmed
the view that the application of the accelerated aging test can serve for predicting
the response of seed to a certain period of natural aging. The possibility to gain a
quick insight into changes in seed that would occur after a specific period of storage
under conventional conditions enable the prediction of optimal conditions for stor-
ing the seed and preventing damage and deterioration of seed during storage
(Balešević-Tubić et al., 2007b). The symptoms observed during accelerated ageing
can be used to characterize the extent of aging, which changes in the opposite direc-
tion of that followed by storability (Smith and Berjak, 1995).
The above-mentioned results were in accordance with the results obtained by
Milošević et al. (1995), according to which the germination of sunflower seed sub-
mitted to accelerated aging declined by 14%, and of soybean seed as much as 50%.
Results of Fabrizius et al. (1999) confirmed a possibility of using accelerated aging
test to predict seed storability. After one year of soybean seed storage, two of the
seven tested lots had the germination rate below 80%
(germination of the remaining
lots was over 90%). The germination rate predicted by using accelerated aging of
seed, for all lots, varied within 10% of the actual germination rate.
F
igure 2: Prediction of seed germination during natural aging of sunflower and soybean
seed based on accelerated aging test (CS12-conventional storage after 12
months; AA3-accelerated aging test for 3 days; AA5- accelerated aging test for 5
days)
