CaCl2 treatment improves drought stress tolerance in barley (Hordeum vulgare L.)
Acta Physiol Plant
CaCl2 treatment improves drought stress tolerance in barley (Hordeum vulgare L.)
Małgorzata Kaczmarek 0 1 2 3 4
Olga Fedorowicz-Stron´ ska 0 1 2 3 4
Katarzyna Głowacka 0 1 2 3 4
Agnieszka Was´kiewicz 0 1 2 3 4
Jan Sadowski 0 1 2 3 4
0 Institute of Plant Genetics, Polish Academy of Sciences , Strzeszyn ́ska 34, 60-479 Poznan ́ , Poland
1 & Olga Fedorowicz-Stron ́ska
2 Communicated by R. Aroca
3 Department of Chemistry, Faculty of Wood Technology, Poznan ́ University of Life Sciences , Wojska Polskiego 38/42, 60-637 Poznan ́ , Poland
4 Department of Biotechnology, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University , Umultowska 89, 61-614 Poznan ́ , Poland
Spring drought can adversely affect the productivity of barley (Hordeum vulgare L.) by reducing the yield. Because seed osmopriming can enhance crop productivity, we examined the potential of CaCl2 treatment to improve drought tolerance in spring barley. Initially, we applied the priming procedure (5, 50, and 500 mM) to caryopses and assessed its effectiveness using a routine germination test, followed by measuring the level of divalent cations. Since drought adaptation is a complex phenomenon, we tested a comprehensive set of physiological parameters including (1) relative water content (RWC), (2) gas exchange parameters, and (3) photosynthetic pigments concentration in leaves of 3-week-old plants developed from the seeds subjected to osmopriming, followed by exposure to increasing water shortage. The plants were sampled at two selected time points, determined by soil moisture retention (pF = 3.6 and 4.2). The effect of CaCl2 pretreatment was characterized in three distinct spring barley varieties, which differed in their response to drought stress (drought-tolerant Sebastian and Cam/B1/C1 and drought-susceptible Georgie), to assess potential interactions between osmopriming and genetically determined drought tolerance. Our results clearly demonstrate that CaCl2 priming improves drought tolerance in stress-tolerant as well as drought-susceptible barley cultivars. Furthermore, we show that the beneficial effects of calcium preconditioning interact significantly with genetically determined drought tolerance.
Barley (Hordeum vulgare L; ) Drought tolerance Osmopriming Germination Calcium chloride Divalent ion content Gas exchange parameters
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Drought is one of several environmental stresses that cause
drastic changes in the growth, physiology, and metabolism
of plants and as a result affect global grain production.
There are various definitions of drought (Wilhite and
Glantz 1985; Dracup et al. 1980), but with respect to
agriculture and food production it can be defined as the
situation where there is insufficient soil moisture to meet
the needs of a particular crop at a particular time. Since
1980s, drought has become more frequent and intense
(Food and Agriculture Organization of the United Nations
[FAO (2012), http://www.fao.org/docrep/017/aq191e/
aq191e.pdf]. It is most commonly associated with parts of
the world such as Africa and Australia, but regional
droughts in Europe are likely to become more severe and
widespread (Olesen et al. 2011). Consequently, there is a
pressing need for improvement in the adaptation of crop
species to drought stress so that high yield and quality can
be maintained.
Seed priming is one of several approaches used to
improve crop productivity (Bradford 1986). Priming refers
to partial imbibition of seeds brought about, for example,
by reducing the soaking time in water (hydropriming),
using soaking solutions with low water potential
(osmopriming or osmoconditioning), or by treating seeds with
hormones (Chen and Arora 2013). Primed seeds initiate
germination without radicle protrusion (Bradford 1986).
The seed priming approaches listed above have been used
to accelerate synchronized seed germination and the
establishment of vigorous seedlings, and to stimulate
vegetative growth and crop yield in many field crops
including wheat (Iqbal and Ashraf 2007a), chickpea (Kaur
et al. 2002) and cotton (Casenave and Toselli 2007). In
addition, it has been reported that seedlings developing
from primed seeds emerge faster, grow more vigorously,
and perform better under diverse conditions such as
drought and salinity stress (Harris et al. 2002; Farooq et al.
2009; Evangelina et al. 2011). However, the effectiveness
of different priming agents is dependent on both the crop
used and the stress conditions imposed (Iqbal and Ashraf
2005).
Seed osmopriming improves germination performance
in various species such as Brassica oleracea (Soeda et al.
2005) and Cucumis melo (Farooq et al. 2007). Furthermore,
in a range of field crops, including rice (Zheng et al. 2002;
Basra et al. 2004; Farooq et al. 2006a), wheat (Nayyar et al.
1995) and sunflower (Kathiresan et al. 1984), osmopriming
with calcium chloride solutions has proved effective in
improving germination rate and stand establishment.
Calcium (...truncated)