SALT TOLERANCE OF SUGAR-BEET AT VARIOUS TEMPERATURES

The salt tolerance of sugar beet (B. vulgaris L.) grown in sand culture under different NaCl levels (0, 2.3, 4.1, 6.0, 8.0, 10.2 and 12.0 -mmho cm-1) was tested at various temperatures (10, 15, 20, 25, 30 and 35.degree. C). There were highly significant differences in seedling emergence 4, 8, 12, 16, 20 and 24 days after planting, in germination index, in seedling dry weight, in number of germinated seeds per cluster and in imbibition value (after 24, 48, 72 and 96 h) as affected by temperatures and salinity levels. Salinity had little effect on seedling emergence at 10-15.degree. C but was increasingly inhibitory as temperature increased from 25.degree. C to 35.degree. C. In the absence of salinity, maximum germination occurred at 25.degree. C, but it decreased drastically with successive increases in temperature. Seedling dry weight and the number of seedlings produced per cluster decreased with increasing salinity and the germination index gradually increased with increasing salinity levels. This effect was more pronounced at temperatures > 25.degree. C. Imbibition increased as temperature increased up to 30.degree. C, but was strongly inhibited at 35.degree. C. Imbibition value decreased as salinity levels increased up to 12.0 mmho cm-1.