Seed priming to improve germination and seedling growth of ...

EurAsian Journal of BioSciences 6: 76-84 (2012)
even ABA. According to Bewley and Black (1982),
seed priming leads to the initiation of primary
metabolic processes, so the time required for
germination is reduced. This positive effect is
probably due to the stimulatory effect of priming on
later stages of the germination process through the
mediation of cell division in germinated seeds
(Sivritepe et al. 2003). Argerich and Bradford (1989)
found that the swelling of the embryo inside primed
tomato seed may speed up germination by
facilitating water absorption. Indeed, the priming is
an effective technique that increases seed vigor and
improves germination and seedling growth
(Jumsoon et al. 1996). Results found in our trial were
consistent with the research work in this area.
Several studies have shown that seed priming
homogenized seed germination in a short period of
time (Khajeh-Hosseini et al. 2003). The maximum
coefficient of velocity of germination were found in
the low salinity treatment and decreased with
increasing salinity. Similar results were reported by
Okcu et al. (2005).
The findings of Ruan et al. (2002a) demonstrated
that priming the rice seed with KCl and CaCl2 had
improved results for germination index. Greater
efficiency of seed priming with KCl is possibly
related to the osmotic advantage that K + has in
improving cell water saturation, and that they act as
co-factors in the activities of numerous enzymes
(Taiz and Zeiger 2002).
In the present study, salt stress causes a
significant reduction in seedling and radicle length,
seedlings fresh and dry weight and vigor index.
Reduction in seedling growth as a result of salt
stress has been reported in several others species
(Achakzai et al. 2010, Akram et al. 2010). Salinity has
both osmotic and specific ionic effects on seedlings
growth (Dioniso-Sese and Tobita 2000). Similarly,
toxic ion accumulation (Na + and Cl - ) negatively affect
plant metabolism (Grieve and Fujiyama 1987). It has
also been reported that salinity suppresses the
uptake of essential nutrients like P and K (Nasim et
al. 2008), which could adversely affect seedlings
growth. Cicek and Cakirlar (2002) have reported that
salinity reduced shoot length, fresh and dry weight
of maize seedlings. Result indicated that seed
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Elouaer and Hannachi
priming significantly improved safflower seedling
growth at different salinity level. Similarly, Katembe
et al. (1998) investigated the effect of seed priming
as a method to improve seedling growth of two
Atriplex species under salt stress. Significant
improvement in root and shoot length may be
attributed to earlier germination induced by primed
over un-primed seeds (Farooq et al. 2005), which
resulted in vigorous seedlings with more root and
shoot length than the seedlings from un-primed
seeds. Our results confirm the findings of Stofella et
al. (1992), who reported that priming of pepper
seeds significantly improved radicle length.
In our study, seedling fresh and dry weights
decreased linearly with increasing salinity. The same
results were also obtained by other researchers
(Mansour et al. 2005). Increased seedling fresh and
dry weight in primed seeds over the un-primed
seeds were also observed by Sivritepe et al. (2003)
who reported an increase in seedling dry weight in
NaCl primed melons seeds under saline conditions as
compared to the un-primed seeds. Seed priming
improve significantly safflower vigor index under
saline conditions. Similar results were found by Ruan
et al. (2002b) who reported that primed rice seeds
showed higher vigor index than non-primed ones.
It is clear from these results that priming improves
germination and growth of many crops. In this
present study, safflower seed showed differential
response to salinity and priming treatments. Reduction
in germination parameters and seedling growth
was more profound in control seeds than primed
seeds. NaCl and KCl seed priming increase germination
of safflower seeds. Thus, the priming may be an
effective method to meet the demands of farmers
during the installation of the culture in the field and
especially in conditions of salt stress. For this reason,
further studies are needed to assess the efficacity of
seed priming during the later stages of the culture.
ACKNOWLEDGEMENTS
This work was supported by the High Institute of
Agriculture, Chatt Mariem and Department of
Horticultural sciences of the university; we wish to
thanks all staff for their technical assistance.