Evaluation of Different Alfalfa (Medicago sativa L.sensu lato)
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.