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Salinity tolerance of Phaseolus species during germination and early seedling growth

Authors:

Bayuelo-Jimenez, J.S.; Craig, R.; Lynch, J.P.

Source:

Crop Science, Crop Science Society of America, Volume 42, Issue 5, USA, p.1584-1594 (2002)

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Abstract:

Salinity tolerance during germination and early seedling growth was evaluated in 24 accessions representing four wild Phaseolus species ( P. angustissimus , P. filiformis , P. leptostachyus and P. microcarpus ) and four accessions of cultivated common bean ( P. vulgaris ). Seeds of the 24 accessions were germinated in sterilized Petri dishes containing germination paper moistened with water or NaCl solution at 0, 60, 120 and 180 mM. Salinity stress delayed germination in all accessions to varying degrees. Eight accessions of P. filiformis germinated fastest under high salinity (120 mM NaCl). Additional wild accessions exhibiting rapid germination at 120 mM NaCl were P. angustissimus , PI535272; P. leptostachyus , PI535336; and P. microcarpus , PI430196. Among the accessions, median germination time (days to 50% germination, T50) at 120 mM NaCl was correlated positively ( r 2 =0.55, P less than or equal to 0.01) with germination in the control treatments. Seeds that germinated rapidly at 60 mM NaCl also germinated rapidly at 120 mM NaCl. At 180 mM NaCl, several accessions reached 50% germination by 6 days, demonstrating high genetic potential within Phaseolus for salinity tolerance during germination. The biomass of radicles plus hypocotyls decreased with increasing salinity. Cluster analysis separated the accessions into three groups. Group I included salt sensitive accessions with late germination, high sensitivity index (ratio of median germination time at 120 mM NaCl versus control), and reduced seedling growth. Group II included salt tolerant accessions with rapid germination, high sensitivity index and enhanced seedling growth. Group III included cultivated accessions corresponding to the Mesoamerican and Andean gene pool with rapid germination, low sensitivity index and intermediate seedling growth. The results confirm that wild Phaseolus species, in particular P. filiformis , representa genetic resource for the improvement of salinity tolerance in common bean.