Water uptake and germination pattern of rice seeds under Iso-osmotic solutions of NaCl and peg, different concentrations of CaCl2 and combinations of NaCl and CaCl2
2003
Alam, M.Z. (Bangladesh Rice Research Inst., Gazipur (Bangladesh). Adaptive Research Div.) | Stuchbury, T. | Naylor, R.E.L. | Rashid, M.A.
Water uptake and pattern of germination of two rice cultivars differing in seed size were determined in iso-osmotic solutions of NaCl and polyethylene glycol, different concentrations of CaCl2 and combinations of NaCl and CaCl2. The results demonstrated that full imbibition of rice seeds occurred at around 30% moisture content (me) and the critical me for germination was around 25- 30%. Although rates of water uptake in rice seeds were reduced with increasing salinity, rice seeds attained full imbibition by 48 h up to 150 mM salinity and reached at least critical me by 72 h up to 250 mM salinity. Water uptakes in NaCl solutions were greater than in iso-osmotic solutions of PEG and rice seeds did not attain even critical me in PEG solutions lower than - 0.232 MPa even after 72 h. When Ca was added in combination with NaCl, water uptake in rice seeds increased. Water uptake in smaller seed was less during the first 12 h of imbibition than larger seeds. However, equilibrium me was attained within 48 h in both large and small seed. The onset of germination declined with increasing concentrations of NaCl and in iso-osmotic solutions of PEG, particularly below-0.457 MPa osmotic potential. Large and small grain rice seed differed significantly in their response to salt and osmotic stress. Supplemental Ca (3 to 9 mM) significantly increased germination percentage compared to no Ca salt stress. Three mM Ca completely offset the deleterious effects of 150 mM NaCl and 6 mM Ca partially offset the deleterious effects of 225 mM NaCl on rice seed germination. Nine mM Ca significantly increased germination in large seed cultivar but not in the small grain cultivar compared to 6 mM Ca.
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