| Pak. J. Bot., 41(4): 1837-1850, 2009. | Back to Contents | ||||
|
|
Updated: 03-09-09 | ||||
|
RELATIONSHIPS BETWEEN SODIUM ION ACCUMULATION AND PHYSIOLOGICAL CHARACTERISTICS IN RICE (ORYZA SATIVA L. SPP. INDICA) SEEDLINGS GROWN UNDER ISO-OSMOTIC SALINITY STRESS
KONGAKE SIRINGAM1, NIRAN JUNTAWONG1, SURIYAN CHA-UM2* AND CHALERMPOL KIRDMANEE2
Abstract: The objective of this research was to elucidate the role of sodium ion (Na+) on photosynthetic machinery and growth characteristics in both salt-tolerant (HJ) and salt-sensitive (PT1) rice varieties grown under iso-osmotic salinity stress. The Na+ and Na+/K+ in HJ and PT1 rice seedlings were increased with increasing salt concentrations in the culture media. K+ in salt-stressed HJ seedlings was increased but that in salt-stressed PT1 seedlings was unchanged. The Na+ accumulation in salt-stressed seedlings was negatively related to the water potential in HJ (r2 = 0.78) and PT1 (r2 = 0.72), leading to pigment degradation i.e. chlorophyll a (Chla), chlorophyll b (Chlb) and total carotenoids (Cx+c). The water potential in both HJ and PT1 salt-stressed seedlings was positively related to the Chla concentration (r2 = 0.78 and r2 = 0.58). Furthermore, Chla and total chlorophyll (TC) concentrations in HJ and PT1 salt-stressed seedlings were positively related to water oxidation in PSII (PSII) as maximum quantum yield of PSII (Fv/Fm) (r2 = 0.73 and r2 = 0.68) and quantum efficiency of PSII (ΦPSII) (r2 = 0.92 and r2 = 0.91), respectively. The ΦPSII in HJ and PT1 salt-stressed seedlings was positively related to the dry matter (r2 = 0.86 and r2 = 0.67). The K+ accumulation in HJ salt-stressed seedlings may play a major role in salt defense mechanisms, leading to enhance on photosynthesis capacity, water oxidation in photosystem II (PSII) and growth abilities.
1Department of Botany, Faculty of Sciences, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand 2National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency (NSTDA), Klong Luang, Pathumthani, 12120, Thailand. *Corresponding author: suriyanc@biotec.or.th |
|||||
|
|
|||||
| Back to Contents |
|
Back to Contents | |||
|
|
|||||