Egypt is considered to be the largest importer countryfor wheat worldwide. Wheat is the main part of the typical diet of the Egyptains.The perdicatable population in Egypt by 2050 will be between115 and 179 million, a drop in rainfall and water decline are also predictable Bokoet al (2007). The consequences of water declination may result in limitation ofthe crop production and expansion in land reclamization.Water inadequacy in arid and semi-arid regions effect crop growth development,productivity yieldand quality, inaddition waterdeficiency found to be affecting expression of genes in plant developmentand growth, (Yang 2004; Shi et al 2008,2009; Galle et al.,2007). Water stress tolerance is the ability of a plant to grow, live,and reproduce acceptably with limited water supply or during water deficit throughdifferent periods during the productionseason (Turner, 1979).
The speed of seed germination may delayed if farmers plant wheatseeds under insufficient amount of rainfall condition or irrigated water. Delayin gerimination may lead also to anotherproblem which is the infection with pathogens, and the missingspots will appear in the field with the destabilized plants. However Seed germination and early seedling growth are actually themost serious times in plant development during water stress, seedgermination can be completely stoppedbecause of drought (Ahmad et al., 2009; Yang et.al. 2016). The response of plant during water stressconditions have become an importantresearch topic particularly in regions affected by water stress.
Seedlingdevelopment and seed germination can be used in testing and selectioncriteria for identifying droughttolerant crop genotypes. Investigations concerning water deficiency duringplant production in their growing seasons usually include seed germination in osmoticum(ASHRAF & ABU-SHAKRA 1978; BASSIRI et al., 1977 ; JOHNSON & ASAY, 1978; Blum et.al. 1980). and seedling growth or survival under conditions ofinduced moisture deficit YOUNIS et al., 1963). Blum et.
al. 1980 postulated thatgenotypic tolerance to mositure stress is specific bioprocess, concerning the level of endosperm utilization, germination rate, seedling growth through water stress and seedling recovery afterwater stress. Differencesamong wheat cultivars in germination characters and seedling parameters werereported in various studies (Kandil etal 2012, Sadat and McNeilly 2000, El-Hendawy etal 2005).Plants genoypes of samespecies in nature have different genetic make up, these variabilityoccured among members of same species makes some of these genotypes more tolerantto biotic or abiotic stresses under the same degree of stress. Screening fordrought tolerance or any other biotic or abiotic stress is essential forimproveming tolerance to different stress. The use of suitable techniques formeasuring stress tolerance is very important. (Mitcell et al., 1998).
One approach to define drought tolerantcultivars at emergence stage is to estimate germination of different wheat genotypes germination underlow soil moisture levels that would be found in semi-arid soils. One simple protocol used todetect water stress as a limiting factor for seed germination is to construct the moisture retention curve,and to select soil moisture stressful level (Brady and Weil, 2010). , wheat crop is one of the few plants that able to evolve andstart germination at an adequate degree in environments of soil water potentialthat lower than -1500 kPa (Lindstrom et.al, 1976). Forspeed up wheat improvement programs, marker-assisted selection (MAS) can be a good tool and fulfill strategy whichcan fascilitate screening germplasm of many crops for thousands of genomicregions under water stress condition, which was, not possible in the past (Ashraf, 2010). Theobjectives of the present study are: (1) screening the response of someEgyptain wheat cultivars for seed germination under water stress levels (2) verificationfor the presence of drought resistant genes in the studied Egyptain cultivarsusing specific molecular markers for drought.