الفهرس 
Photosynthetic pigmentsOnly 14 pages are availabe for public view
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Abstract
Salinity is one of the oldest enemies of agriculture. Excess amount
of salts in the soil or irrigation water adversely affect plant growth and
development. Nearly 20% of the world’s cultivated areas are affected
by salinity (Zhu, et al., 2010). Seedling growth, flowering and fruit set
are influenced by high salt concentration leading to diminished
economic yield (Sairam and Tyagi, 2004 and Bybordi and
Tabatabaei, 2009).
Salinity is considered as a severe problem in agriculture since it
results in a noticeable reduction in crop productivity (Bybordi, et al .,
2010b).Generally, salinity can affect germination, metabolism, the size of
plants, branching, leaf size and overall plant anatomy. Salt also affects
photosynthetic components such as enzymes, chlorophyll and
carotenoids contents (Heidari, 2012).
In fact, soil salinity is an important growth-limiting factor for nonhalophytic
plants (Bybordi, et al., 2010b). Salts inhibit plant growth
by osmotic stress, nutritional imbalance, and specific ion toxicity
(Hussain, et al., 2010). Also salinity damage is mainly due to altered
water relation caused by high salt accumulation in the intercellular
spaces (Zhang, et al., 2006). One of the major constraints of salt stress
is nutrient imbalance (Jadhav, et al., 2010).Abiotic pressure like salt stress and chemical insulate impose
limitation on crop productivity and also limit land available for
farming, often in regions that can ill afford such as constraints, thus
highlighting a greater need for understanding how plants respond to
adverse conditions with the hope of improving tolerance of plants to
environmental stress (Joseph, et al., 2010).However, one of the cost effective strategies for counteracting
salinity stress involves growing crops possessing inherent ability to
tolerate saline conditions (Ashraf and Harris, 2004 and Sabir and
Ashraf, 2008a). Furthermore incorporating factors that enable plants to
tolerate salt stress could improve growth and production under saline
conditions (Ashraf and Foolad, 2007, Sharifi, et al., 2007 and
Ashraf, et al., 2008a). However alleviation of salinity problem is
expensive and often represents only a temporary solution.
In Egypt the cultivated regions restricted to the Nile Valley which
depends on fresh water of the Nile river for irrigation does not exceed
4% of the total Egypt land area according to (Younis, et al., 1994).
The toxic effects of salt on plants are the consequence of both a water
deficit that results from the relatively high solute concentrations in the
soil as well as a stress specific to Na+ and Cl- resulting in a wide variety
of physiological and biochemical changes that inhibit plant growth
development and proteins synthesis (Taffouo, et al., 2010 a and b).