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- Author or Editor: Steven H. Goertz x
Abstract
White and brown accessions of tepary bean (Phaseolus acutifolius Gray var. latifolius) and navy bean (Phaseolus vulgaris L. ‘Fleetwood’) were germinated at 0.0, −0.5, −1.0, −1.5, −2.0, and −2.5 MPa of NaCl at 25 or 35C for 9 days. Differences in germination percentages and rates between the two species were significant, especially at the higher salt concentrations. At 25C and salinities greater than or equal to − 2.0 MPa, tepary accessions had significantly higher percentage germination and germination rates than navy. At 35C this difference was noted at −1.5 MPa. The fresh weights of root plus hypocotyl appeared lower than controls at even the lowest concentration of salinity (− 0.5 MPa), suggesting that seeds germinated with NaCl did not produce vigorous seedlings. Of the three beans tested, the two tepary beans were more tolerant to NaCl than the navy bean, with the white tepary being most tolerant.
Seeds of two tepary bean lines (Phaseolus acutifolius Gray var. latifolius) and one navy bean cultivar (P. vulgaris L. `Fleetwood') were tested with 0.0-, – 0.3-, –0.6-, -0.9-, -1.2-, or – 1.5-MPa NaCl solutions to determine their relative salt tolerance during germination and emergence. Developmental stage was not affected at – 0.3 MPa, but with salinities more negative than -0.9 MPa, `Fleetwood' developed more slowly than the tepary lines; no plants emerged at – 1.5 MPa. Teparies tended to maintain higher water and osmotic potentials than navy over the range of NaCl concentrations used, although turgor was similar for all three genotypes. Leaf area was reduced more in navy than in white tepary at – 0.6 and – 0.9 MPa. Dry weights of navy were higher than those of either tepary bean at all NaCl concentrations, although decreases at higher salinities relative to 0.0 MPa were greater for navy than for teparies. Root: shoot ratios were higher at – 0.3 MPa than at 0.0 MPa, but were lower at the higher NaCl concentrations for all three genotypes. Overall, tepary beans tolerated NaCl better than navy. The characteristic that best indicated differences in salt tolerance was developmental stage.