GENOTYPIC VARIATIONS IN SALT TOLERANCE OF SOME EGYPTIAN WILD BEET ACCESSIONS
2018
S. Hussin
This study reports for the first time the eco-physiological responses of some Egyptian wild beet accessions (WB1013, WB1021 and WB1026) under saline irrigation. The plants were exposed to five seawater salinities (0, 20, 30, 40 and 60% sws) for 6 weeks in a sandy culture in the greenhouse. Low salinity (20% sws) slightly enhanced the plant fresh weight of both WB1013 and WB1021 genotypes by 5% and 3% respectively, but significantly reduced that of WB1026 genotype by about 10%. Higher seawater salinities, however, caused progressive growth reductions in all accessions, with maximum growth inhibition, being 59% in WB1026 at 60% sws. Tolerance threshold was lowest (being at 20% sws) for WB1026, but highest (reached 40% sws) for both genotypes WB1013 and WB1021. EC50 was at salinity level of 40 – 60% sws for WB1026 genotype, but higher than 60% sws for genotypes WB1013 and WB1021. These indicate that both accessions WB1013 and WB1021 are more salt-tolerant when compared with WB1026. The higher salt tolerance of WB1013 and WB1021 accessions is largely conferred by higher leaf K+/Na+ ratio, due to low Na+ and Cl- accumulation under saline conditions compared to WB1026. This was associated with lower dry weights and ion leakage, and with higher leaf area, chlorophyll readings, total soluble carbohydrates and Ca2+ concentrations when compared with WB1026. Both WB1013 and WB1021 accessions do not only offer the possibility of being an alternative promising cash crops under seawater irrigation, but also, through an understanding of its physiology, may provide possible routes to enhance salt tolerance in other beet crops.
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