ISHS Acta Horticulturae 511: XXV International Horticultural Congress, Part 1: Culture Techniques with Special Emphasis on Environmental Implications - Nutrient Management
SALT-INDUCED REDUCTION OF GROWTH IN -BRASSICA RAPA- L |
| Authors: | T.R. Kwon, P.J.C. Harris, W.F. Bourne, W.S. Lee |
| Keywords: | Brassica rapa, potassium, proline, salinity tolerance, sodium |
| Abstract:
Brassica rapa L., 'Sani' were grown in a continuous aerated hydroponic system with 125 mol m-3 NaCl for 12 days. The NaCl-treated plants were moved to and grown in NaCl-free nutrient solution for a further 6 days. This study aimed to investigate 'ionic effects' of salinity such as Na+ and K+ accumulation and 'water-deficit effects' of salinity such as dry to fresh weight ratio, total soluble sugar and proline accumulation. Salinity increased Na+ content, dry to fresh weight ratio and proline accumulation but decreased K+ content in leaves. Proline accumulation in the presence of salinity was leaf-age dependent with significant higher in young leaves than mature leaves. After the desalinization, the K+ and Na+ contents of mature leaves did not change significantly while young leaves showed great reduction of Na+ and increase of K+, indicating that mature leaves suffered irreversible excessive ion toxicity or imbalance even after the removal of NaCl from the growth media. Mature and young leaves sharply decreased dry to fresh weight ratio and proline in response to the desalinization, indicating that 'water-deficit effects' of salinity is a reversible after the removal of salt stress. It is concluded that the growth of salt-stressed Brassica rapa plants can be affected by irreversible 'ionic effects' in mature leaves and by reversible 'water-deficit effects' mainly in young leaves. | |
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