Evaluation of Different Alfalfa (Medicago sativa L.sensu lato) Varieties
Under Different Concentrations of NaCl During Germination Stage

Manal M. Hefny (1) and R. Doliñski (2)
(1)Agron.Dept.,Fac. of Agriculture,Suez Canal Univ., Ismailia,Egypt. (2)Institute of Plant Breeding and Genetics,Agric.Univ.,Lublin,Poland

Alfalfa(Medicago sativa L.)is the predominant perennial legume species used as forage crop or pastures,it is grown and produced largely in irrigated arid and semiarid regions.Such regions are affected seriously by salinity, which results in decreasing the area of arable lands.Salinity effects may vary depending upon the growth stage at the time of stress,meaning that, salt tolerance at germination is not consistently related to tolerance during emergence, vegetative growth, flowering or fruiting (Shannon, 1985). While, maximum genetic gain in salt tolerance during germination of alfalfa seeds may only be achieved by selection in solutions containing more than one salt(Rumbaugh,et al.,1993),selection in NaCl solutions may account for most of the potential gain.Also,germination percentage decreased and germination time increased with increasing salinity(Lombardo and Saladino, 1997).Because saline soils and water extremely limit the productivity of crop and pasture lands in semiarid and arid environments,the development of cultivars with the ability to germinate under high salt stress would be useful in such soils. Therefore, fourteen alfalfa (Midicago sativa L. sensu lato)varieties,five Polish,four Egyptian,four Hollandian and one American were evaluated under nine concentrations of NaCl at Institute of Plant Breeding and Genetics,Agricultural University,Lublin,Poland.Results showed significant differences among varieties across NaCl concentrations for the germination characters, indicating that, such characters were influenced by both varieties and NaCl levels.In addition,the Egyptian variety ISM-94, was the best variety among the genetic materials,since,it represented the highest IC50 value (229 mM),mean germination percent(64.60%),mean adjusted germination percent(73.40%),the longest radicle and hypocotyl(36.10mm and 25.90mm,respectively)and more rapid germination.Also,highly significant (P(0.01)differences were found among the mean IC50 values of the centers of diversity and among the subspecies,as anticipated,germplasm from the more arid Indian and African centers were better able to tolerate NaCl during germination(Rumbaugh and Pendery,1990).It is obvious that,the concentration 120 mM was the critical one which above it,an observed reduction in the characters mean has been occurred .The moderate value of heritability with reasonable genotypic variance which has been obtained,make selection and improvement of salt tolerance during germination possible.
1-Lombardo,V., Saladino, L. 1997. Effect of salinity of water on seed
germination capacity. Note II. Irrigazione -e- Drenaggio 44: 3-7.
2-Rumbaugh,M.D. Pendery, B. M. 1990. Germination salt resistance of alfalfa
(Medicago sativa L.) germplasm in relation to subspecies and centers
of diversity. Plant and Soil 124: 47-51.
3-Rumbaugh,M. D. , Johnson,D.A., Pendery, B.M. 1993.Germination inhibition
of alfalfa by two-component salt mixtures. Crop Sci., 33 : 1046 - 1050.
4-Shannon, M. C. 1985. Principles and strategies in breeding for higher
salt tolerance.Plant and Soil 89: 227-241.

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