الفهرس 
Introduction
Materials and MethodsOnly 14 pages are availabe for public view
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Abstract
The objective of this study was to investigate the effects of naci stress on growth and some related physiological activitied of wheat cultivars (sids 12, sids4, bani sweif 2 and giza 165 ) the main experimental results can be summarized in the following points : 1- A considerable variation in the salt tolerance among the four studied wheat cultivars has been observed. this variation was also revealed among the shoots and roots of each cultivar. the results revealed that cv. sids 12 cultivar had a gradual decrease in dry matter mass production with increasing salt level, but in cvs. sids 4 and bani sweif 2, there is a significant reduction in dry matter production of different organs
Wheat (Triticum aestivum L.) is the staple foods for more than 35%
of world population (Almaghrabi, 2012). Wheat is the most important
and widely adapted food cereal in Egypt. However, egypt supplies
only 40% of its annual domestic demand for wheat ( Abdel Latef,
2010).
Egypt is one of the countries that suffer from severe salinity
problems. For example, 33% of the cultivated land, which comprises
only 3% of total land area in Egypt, is already salinized due to low
precipitation (<25mM annual rainfall) and irri- gation with saline
water (Abdel Latef, 2010). Soil salinity has been a major concern to
global agriculture throughout human history (Zhang et al., 2011).
Soil salinity is one of the significant abiotic stresses for plant
agriculture worldwide up to 20% of the irrigated arable land in arid
and semi-arid regions is already salt affected and that portion is still
expanding (Yeilaghi et al., 2012).
Under salt stress, plants have to cope with water stress imposed bythe low external water potential and with ion toxicity due to
accumulation of ions inside the plants (Romero-Aranda et al., 2006).
In addition to its known components of osmotic stress and ion toxicity,
salt stress is also manifested as an oxidative stress, which contributes
to its deleterious effects (Hernández et al., 2001, Teixeira and
Pereira, 2007).
Roots are usually the first tissues exposed to sodium stress. For this
reason, and the fact that roots depend on mitochondria for most of
cellular energy production, sodium stress related impairment ofmitochondria function is likely to be particularly important in roots
(Hamilton and Heckathron, 2001).
During the continuous exposure of salt to the plant, the rate of
export from the root can exceed the rate of compartmentalization in the
shoot. If this occurs, salt ions will accumulate outside the vacuole,
either in the cytoplasm or in the apoplast and produce toxicity
symptoms (Shahzad et al., 2011).
The physiological responses of plants for survival in stressed
environment are based on their ability to express the pre-existing
defense program or adaptation, in which plants adjust to the stress.
Under stress condition, the adaptive responses are elicited by plants
mainly through changes in endogenous levels as well as balances of
phytohormones (Senthila et al., 2005). The reestablishment of
hormonal equilibrium under the new environment probably plays a
central role in the survival of plants under stress condition (Amzallagand Lerner, 1995).
Salinity can affect germination, metabolism, the size of plants,
branching, leaf size and overall plant anatomy. The inhibitory effect of
salt stress on plant growth is exhibited at several levels and involves an
array of cellular processes such as cell division and expansion. These
cellular processes are regulated by hormones for which homeostasis
may be altered by salt (Rodŕiguez et al., 2006).
The most typical morphological symptom of saline injury of plants
is reduction of growth (Abdel Latef, 2005 and Abou Alhamd, 2007).The reduction in shoot biomass production by the plant may be due
to the chlorosis and necrosis of the leaves that reduce the photosynthetically
active area (De Herralde et al., 1998Photosynthesis is one of the most important biochemical pathways
by which Plants prepare their own food material and grows. Salinity
stress causes changes in chloroplast ultrastructure (Keiper et al., 1998)
and there is also a decrease in rate of photosynthesis under saline
conditions (Sixto et al., 2005) based on species and clones of genus.
Chlorophyll content in plants correlates directly to the healthiness of
plant (Zhang et al., 2005). as a matter of fact, there has been
knowledge on increase of chlorophylls in saline environment
depending on salt levels (Romero-Aranda et al., 2001).
The total chlorophylls content decreases under NaCl salinity stress
(Jaleel et al., 2008 and Hudai and Arzu, 2008).
Usually there is a dominance of chlorophyll (a) over chlorophyll (b)
in plants but their values become closer with increasing salinity (Mane
et al., 2010). The decrease in chlorophyll under stress is a commonlyreported phenomenon and in various studies, this may be due to
different reasons, one of them is related to membrane deterioration
(Tantawy et al., 2009 and Mane et al., 2010).
Carbohydrates represent the most important compounds so far as
dry matter production and energy relations of cells concerned
(Mane et al., 2011).
Salt stress has a different effect on carbohydrate contents. In this
respect, some authors have reported carbohydrates accumulation in
various plants under salinity condition (Abd El Samad and Azooz,
2002, Parida et al., 2003 and Azooz et al., 2004a). On other hand,
Abdel Latef et al. (2009) observed that at low and moderate salinitylevels sugars and consequently the total carbohydrates were decreased.