Germination responses of endemic land-races of Saudi-Arabian cereal species

This investigation of endemic land-races of Saudi-Arabian cereals, Triticum aestivum, Triticum durum, Hordeum vulgare, Panicum miliaceum and Pennisetum glaucum was aimed at identifying and characterizing stress-tolerant populations appropriate for germplasm-banking. Native soils were saline, nutrient-poor, sandy and subject to seasonal drought and hot summers. Consequently, the work focused on responses of germination and early growth to salinity (0-1000 mM NaCl) and high temperatures, using mainly thermogradient plates and incubators. I examined germination rate, enforced dormancy and viability, in recently collected seeds and in material naturally or artificially aged under different storage conditions. Electrolyte leakage (measured as electrical conductivity) was evaluated as an indicator of deterioration of wheat seed quality. The germination responses to salinity of all five species showed remarkable tolerance, these cereal species are not normally regarded as halophytes but the behaviour of these land races suggested tolerance as high as that of many true halophytes of coastal salt marshes. None of these species showed significant dormancy, presumably as a result of previous domestication, and none showed critical temperature requirement for germination found in many wild species of adverse environments. It is additionally proposed that dry biomass can be an indication for quick inspection of crops under salinity stress. Salt stress similarly results in a significant reduction in the fresh and dry masses of leaves. Due to their response to salinity and significant positive correlation with germination and biomass these characters could be used to assess wheat genotypes under saline field environments. The germination response to artificial ageing was most influenced by the salt stress NaCl during the incubation period particularly at higher concentration of 500, 1000 NaCl mM. The initial moisture content of seeds resisted ageing when being low. The conclusion is that development of plants with increased resistance to inhibition of growth by the osmotic effects of external salinity is both feasible and desirable.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of East Anglia

Year dc:date.issued

2014

Author dc:creator

• Albarih, Sami

Language dc:language

en