Identification and Selection for Salt Tolerance in Alfalfa (Medicago sativa L.) Ecotypes via Physiological Traits

Hassan Monirifar,Maryam Barghi

doi:10.15835/nsb113498

Abstract

Salt stress is a serious environmental problem throughout the world which may be partially relieved by breeding cultivars that can tolerate salt stress. Plant breeding may provide a relatively cost effective short-term solution to the salinity problem by producing cultivars able to remain productive at low to moderate levels of salinity. Five alfalfa cultivars, ‘Seyah-Roud’, ‘Ahar-Hourand’, ‘Oskou’, ‘Malekan’ and ‘Sefida-Khan’ were assessed for salt tolerance at mature plant stage. A greenhouse screening system was used to evaluate individual alfalfa plants grown in perlit medium, and irrigated with water containing different amounts of NaCl. Three salt levels were achieved by adding 0, 100 and 200 mM NaCl to Hoagland nutrient solution, respectively. Forage yield, sodium and potassium contents and K/Na ratio was determined. Also, leaf samples were analyzed for proline and chlorophyll contents. The ecotypes Seyha-Roud and ‘Sefida-Khan’ had comparatively less sodium contents than ‘Oskou’, ‘Ahar-Hourand’ and ‘Malekan’ ecotypes, also potassium content increased under saline condition. Forage yield of different alfalfa ecotypes was significantly influenced by the salinity. The ecotypes ‘Malekan’, Ahar- Hourand and ‘Oskou’ were successful in maintaining forage yield under salinity stress. Sodium contents increased due to salinity in all alfalfa ecotypes however ecotypes ‘Ahar-Hourand’ and ‘Malekan’ maintained the highest leaf Na concentration. They showed higher content of K than other ecotypes but had lower K/Na ratio. It was concluded that, two ecotypes ‘Malekan’ and ‘Ahar-Hourand’ were better.

Highlights

10 percent of the earth’s land is salt-affected and an estimated 10 million ha of agricultural land are lost annually due to salinization and water logging
Several reports indicate that alfalfa has the genetic potential for improved salt tolerance and that plant breeding may be the solution for increasing yield in saline environments ( Johnson et al, 1992; Mohammad et al, 1984; Noble et al, 1984)
Monirifar et al, (2004) reported the presence of phenotypic variation between some Azarbaijan alfalfa cultivars at different salinity levels and changing in forage yield resulting from saline stress

Summary

Introduction

10 percent of the earth’s land is salt-affected and an estimated 10 million ha of agricultural land are lost annually due to salinization and water logging. Breeding for improved salt tolerance in many crop plants, including alfalfa, has progressed slowly (Blum, 1988; Johnson et al, 1992; Noble et al, 1984). Salinity research in alfalfa has focused primarily on germination (Carlson et al, 1983; Allen et al, 1986., Dobrenz et al, 1989) and seedling establishment (Ashraf et al, 1987; Mckimmie and Dobrenz, 1987) in the presence of NaCl. Several reports indicate that alfalfa has the genetic potential for improved salt tolerance and that plant breeding may be the solution for increasing yield in saline environments ( Johnson et al, 1992; Mohammad et al, 1984; Noble et al, 1984). The presence of phenotypic variation for salt tolerance was reported for alfalfa cultivars (Al-Khatib et al, 1993; Noble et al, 1984).

Results

Conclusion