NaCl Salt Stress Research Articles

Biochemical Alterations in Foliar Tissues of Citrus Genotypes Screened In vitro for Salinity Tolerance

Soil salinity is a prime impediment in the commercial production of citrus. In the present study two citrus rootstock genotypes viz. Citrus jambhiri and Citrus karna were cultured in vitro and exposed to NaCl salt stress. The previously standardized protocol was used for culture establishment and in vitro shoot and root regeneration. NaCl in different concentrations (25, 50, 75, 100 and 125 mM) was added in standardized regeneration and rooting media to note the biochemical changes due to salinity stress. Results revealed that salinity stress adversely affected the shoot and root differentiation and proved lethal above 100 mM NaCl. The hardening was also hampered due to salt stress. Among different biochemical parameters, proline, total soluble proteins and total sugars accumulation were enhanced however; total chlorophyll content was reduced under salinity stress. The revelation of some new protein polypeptides (21, 26 and 54 kDa) at different increasing salinity levels was attributed to their significance in stress alleviation.

Different Physiological Responses of Male and Female Ginkgo biloba (Ginkgoaceae) Seedlings to Salt Stress

In the present study, male and female Ginkgo biloba seedlings were used to examine changes in gas exchange, the intrinsic water use efficiency (WUE), free proline (Pro) content, peroxidase (POD) and superoxide dismutase (SOD) activity under the condition of adding 40 mmol L-1 NaCl solution into the soil monitoring the soil under the salt-stress. The results showed that the net photosynthetic rate, stomatal conductance and transpiration rate in salt-stressed female G.biloba seedlings decreased 45.87%, 25.00%, 16.47% respectively, while the stomatal conductance, intercellular CO2 concentration, and transpiration rate in salt-stressed male seedlings increased 10.00%, 8.10%, 22.95%, respectively comparing with control; Significantly, lower levels of the WUE were observed in both salt treated female and male seedlings which decreased (P=0.020), 30.47% and 46.38% respectively. Salt-stressed male seedlings were found higher level of free Pro content while no significant change were found in the same treated female seedlings. The SOD activities in both treated seedlings decreased 22.96% and 23.18% respectively without significant variations. Furthermore, the activities of POD in salt treated female seedlings decreased significantly, while that of the male showed no significant change at all. It was indicated that under 40 mmol L-1 NaCl salt stress treatment female seedlings maintained higher photosynthetic rate to accumulate energy, lower transpiration rate and higher intrinsic water use efficiency to reduce disperse of water content, and higher antioxidant enzyme activities to relieve oxidative stress which may resulted in female seedlings received less negative effect than male seedlings under salt stress condition.

Different Physiological Responses of Male and Female Ginkgo biloba (Ginkgoaceae) Seedlings to Salt Stress

In the present study, male and female Ginkgo biloba seedlings were used to examine changes in gas exchange, the intrinsic water use efficiency (WUE), free proline (Pro) content, peroxidase (POD) and superoxide dismutase (SOD) activity under the condition of adding 40 mmol L-1 NaCl solution into the soil monitoring the soil under the salt-stress. The results showed that the net photosynthetic rate, stomatal conductance and transpiration rate in salt-stressed female G.biloba seedlings decreased 45.87%, 25.00%, 16.47% respectively, while the stomatal conductance, intercellular CO2 concentration, and transpiration rate in salt-stressed male seedlings increased 10.00%, 8.10%, 22.95%, respectively comparing with control; Significantly, lower levels of the WUE were observed in both salt treated female and male seedlings which decreased (P=0.020), 30.47% and 46.38% respectively. Salt-stressed male seedlings were found higher level of free Pro content while no significant change were found in the same treated female seedlings. The SOD activities in both treated seedlings decreased 22.96% and 23.18% respectively without significant variations. Furthermore, the activities of POD in salt treated female seedlings decreased significantly, while that of the male showed no significant change at all. It was indicated that under 40 mmol L-1 NaCl salt stress treatment female seedlings maintained higher photosynthetic rate to accumulate energy, lower transpiration rate and higher intrinsic water use efficiency to reduce disperse of water content, and higher antioxidant enzyme activities to relieve oxidative stress which may resulted in female seedlings received less negative effect than male seedlings under salt stress condition.

Effect of glycinebetaine on proline, water use, and photosynthetic efficiencies, and growth of rice seedlings under salt stress

The aim of this investigation was to improve salt tolerance abilities prior to rice crop harvesting, including proline accumulation, pigment stabilization, water use efficiency (WUE), photosynthetic efficiency, and growth, by using exogenous foliar-sprayed glycinebetaine (Glybet). Pathumthani 1 (PT1) is reported to be a salt-sensitive cultivar and it was selected as a model plant. The proline content of PT1 rice was enriched by 50 mM of foliar-sprayed Glybet, thereby maintaining WUE and pigment stabilization, leading to high photosynthetic performance in chlorophyll a fluorescence and CO_2 assimilation, and increasing plant height when the plant was exposed to 150 mM of NaCl salt stress. The photosynthetic abilities in plants undergoing Glybet application were positively related to seed fertility percentage, leading to improved seed grain under salt stress conditions. In addition, the overall performance, i.e. that of pigments, chlorophyll a fluorescence, photosynthetic abilities, and growth characters of PT1 rice treated with 200 mM of Glybet, was inhibited with this extreme dosage. Exogenous foliar-applied Glybet in optimum doses should be used as a short-term technique for the improvement of salt tolerance in rice.

Different Physiological Responses of Male and Female Ginkgo biloba (Ginkgoaceae) Seedlings to Salt Stress

In the present study, male and female Ginkgo biloba seedlings were used to examine changes in gas exchange, the intrinsic water use efficiency (WUE), free proline (Pro) content, peroxidase (POD) and superoxide dismutase (SOD) activity under the condition of adding 40 mmol L-1 NaCl solution into the soil monitoring the soil under the salt-stress. The results showed that the net photosynthetic rate, stomatal conductance and transpiration rate in salt-stressed female G.biloba seedlings decreased 45.87%, 25.00%, 16.47% respectively, while the stomatal conductance, intercellular CO2 concentration, and transpiration rate in salt-stressed male seedlings increased 10.00%, 8.10%, 22.95%, respectively comparing with control; Significantly, lower levels of the WUE were observed in both salt treated female and male seedlings which decreased (P=0.020), 30.47% and 46.38% respectively. Salt-stressed male seedlings were found higher level of free Pro content while no significant change were found in the same treated female seedlings. The SOD activities in both treated seedlings decreased 22.96% and 23.18% respectively without significant variations. Furthermore, the activities of POD in salt treated female seedlings decreased significantly, while that of the male showed no significant change at all. It was indicated that under 40 mmol L-1 NaCl salt stress treatment female seedlings maintained higher photosynthetic rate to accumulate energy, lower transpiration rate and higher intrinsic water use efficiency to reduce disperse of water content, and higher antioxidant enzyme activities to relieve oxidative stress which may resulted in female seedlings received less negative effect than male seedlings under salt stress condition.

Phenotypic and Transcriptomic Analyses of Mildly and Severely Salt-Stressed Bacillus cereus ATCC 14579 Cells

Bacteria are able to cope with the challenges of a sudden increase in salinity by activating adaptation mechanisms. In this study, exponentially growing cells of the pathogen Bacillus cereus ATCC 14579 were exposed to both mild (2.5% [wt/vol] NaCl) and severe (5% [wt/vol] NaCl) salt stress conditions. B. cereus continued to grow at a slightly reduced growth rate when it was shifted to mild salt stress conditions. Exposure to severe salt stress resulted in a lag period, and after 60 min growth had resumed, with cells displaying a filamentous morphology. Whole-genome expression analyses of cells exposed to 2.5% salt stress revealed that the expression of these cells overlapped with the expression of cells exposed to 5% salt stress, suggesting that the corresponding genes were involved in a general salt stress response. Upregulation of osmoprotectant, Na(+)/H(+), and di- and tripeptide transporters and activation of an oxidative stress response were noticeable aspects of the general salt stress transcriptome response. Activation of this response may confer cross-protection against other stresses, and indeed, increased resistance to heat and hydrogen peroxide could be demonstrated after preexposure to salt. A temporal shift between the transcriptome response and several phenotypic responses of severely salt-stressed cells was observed. After resumption of growth, these cells showed cellular filamentation, reduced chemotaxis, increased catalase activity, and optimal oxidative stress resistance, which corresponded to the transcriptome response displayed in the initial lag period. The linkage of transcriptomes and phenotypic characteristics can contribute to a better understanding of cellular stress adaptation strategies and possible cross-protection mechanisms.

Proline Accumulation, Photosynthetic Abilities and Growth Characters of Sugarcane ( Saccharum officinarum L.) Plantlets in Response to Iso-Osmotic Salt and Water-Deficit Stress

The aim of this study was to investigate the biochemical, physiological and morphological responses of sugarcane to iso- osmotic salt and water-deficit stress. Disease-free sugarcane plantlets derived from meristem cuttings were photo- autotrophically grown in MS media and subsequently exposed to −0.23 (control), −0.67 or −1.20 MPa iso-osmotic NaCl (salt stress) or mannitol (water-deficit stress). Chlorophyll a (Chl a), chlorophyll b (Chl b), total carotenoids (C x+c), maximum quantum yield of PSII (Fv/Fm), photon yield of PSII (ΦPSII), stomatal conductance (Gs) and transpiration rate (E) in the stressed plantlets were significantly reduced when compared to those of plantlets of the control group (without mannitol or NaCl), leading to net-photosynthetic rate (Pn) and growth reduction with positive correlation. In addition, physiological changes and growth parameters of plantlets in the salt stress conditions were more sharply reduced than those in water- deficit stress conditions. On the other hand, the proline content and non-photochemical quenching (NPQ) in the leaves of stressed plantlets increased significantly, especially in response to iso-osmotic salt stress. The chlorophyll pigments in iso-osmotic stressed leaves were significantly degraded ( r 2 = 0.93), related to low water oxidation ( r 2 = 0.87), low netphotosynthetic rate ( r 2 = 0.81), and growth reduction ( r 2 = 0.97). The multivariate biochemical, physiological and growth parameters in the present study should be further used to develop salt, or drought, tolerance indices in sugarcane breeding programs.

Impact of Anatomic Site on Growth, Efflux-Pump Expression, Cell Structure, and Stress Responsiveness of Bacteroides fragilis

This study investigated whether B. fragilis from various human sites acquired stable traits enabling it to express certain efflux pumps (EPs), adopt a particular cell structure, and tolerate certain stressors. Isolates from blood, abscess, and stool (n = 11 each) were investigated. Bacteria from various sites portrayed different ultrastructres and EP expression. Blood isolates were tolerant to nutrient limitation and stool isolates to NaCl and bile salt stress. Stressors significantly increased EP expression. These data demonstrate that (1) B. fragilis acquires stable traits from various in vivo microenvironments; (2) that EPs are involved in stress responsiveness; and (3) that EP expression is tightly controlled and site dependent.

Carbon monoxide counteracts the inhibition of seed germination and alleviates oxidative damage caused by salt stress in Oryza sativa

Although carbon monoxide (CO) has always been regarded as a toxic gas, recent reports suggested that it is one of the products of heme oxygenase (HO; EC 1.14.99.3) catalysis in animals, and could confer beneficial cytoprotection against oxidative damage. Here, we investigated the effects of exogenous putative CO donor hematin and CO aqueous solution on rice seed germination under 100 mM NaCl salt stress. Both hematin and CO aqueous solution dose-dependently attenuated the inhibition of seed germination and seedling growth caused by salinity. Moreover, 1.0 μM hematin and 5% CO-saturated aqueous solution activated amylase activity, thus accelerating the formation of reducing sugar and total soluble sugar. Furthermore, hematin and CO aqueous solution induced catalase (CAT) and superoxide dismutase (SOD) activities, thus resulting in the alleviation of oxidative damage, as indicated by the decrease of thiobarbituric acid reactive substances (TBARS) content. Such above CO-induced effects were also confirmed by using semi-quantitative RT-PCR, including the up-regulation of expression patterns of α-amylase, CAT and Cu/ Zn-SOD genes. Also, the similar function of hematin might contribute to endogenous HO-derived CO, since addition of the CO-specific synthetic inhibitor zinc protoporphyrin IX (ZnPPIX) and CO scavenger hemoglobin (Hb) reversed above effects. Meanwhile, further results also proved that treatment with hematin for 36 h could result in the potent induction of HO-1 transcript, HO activity and CO content in the germinating seeds. Collectively, these results indicated that CO performed an advantageous effect on attenuation of inhibition of seed germination and seedling growth induced by salt stress, and alleviated oxidative damage via activating anti-oxidant enzymes.

Water Relation, Photosynthetic Ability and Growth of Thai Jasmine Rice (Oryza sativaL. ssp.indicacv. KDML 105) to Salt Stress by Application of Exogenous Glycinebetaine and Choline

AbstractRice reportedly possesses a very low capacity to accumulate glycinebetaine (Glybet), but may be accumulated by the exogenous application of Glybet or Choline (Cho) as an alternative way to improve its salt‐tolerant ability. The aim of this research was to determine whether Glybet accumulation could be induced in Thai jasmine rice by the exogenous application of Glybet and Cho, and to determine the effects of Glybet and Cho treatment on various growth parameters of seedlings cultured under salt‐stress conditions. Thai jasmine rice seeds were aseptically germinatedin vitroon solidified Murashige–Skoog media, supplied with either Glybet or Cho in the culture media for 12 days and then treated with 342 mmNaCl (salt stress) for 4 days. GlyBet content, water relation, photosynthetic capabilities and growth characteristics of salt‐stressed seedlings were measured. The addition of Glybet or Cho to plant culture media containing 342 mmNaCl resulted in increased accumulation of Glybet in rice seedlings. Increased Glybet accumulation was strongly associated with a high efficiency of water usage (r = 0.96), which in turn correlated with increased maximum quantum yield of PSII (Fv/Fm) (r = 0.86). Moreover, the pigment concentrations of seedlings cultured under salt stress were maintained by a function of Glybet, led to high efficiency of photochemical and non‐photochemical quenching of PSII as well as to exhibit on net photosynthetic rate. Thus, our results suggest that the addition of either Glybet or Cho to the plant growth media can improve growth performance under salt stress conditions by increasing the salt tolerance of Thai jasmine rice. The exogenous application of Glybet and/or Cho to culture media may be an effective method of improving resistance to salt stress via the promotion of Glybet accumulation with in rice seedlings.

Changes in growth and in solute concentrations in sorghum leaves and roots during salt stress recovery

Seedlings of two sorghum genotypes [ Sorghum bicolor (L.) Moench], one salt tolerant (CSF 20) and another salt sensitive (CSF 18) were exposed to 0 (control) and 100 mM NaCl (salt stress) in nutrient solution for seven days and, then, transferred to a new nutrient solution with no added NaCl for an additional period of five days (salt recovery). Plants were collected at the 7th (salt stressed) and 12th days (salt recovered) and relative growth rate (RGR) and organic and inorganic solutes in leaves and roots were determined. Salinity reduced RGR and increased Na +, Cl −, soluble carbohydrates and proline concentrations, and Na +/K + and Na +/Ca 2+ ratios, especially in the leaves of the salt sensitive genotype. During salt stress recovery, RGR of roots was lower in previously stressed seedlings, but shoot growth did not differ between these seedlings and control unstressed ones, in both genotypes. Salt recovered seedlings showed decrease in leaf Na + plus Cl − concentrations and in Na +/Ca 2+ ratio, and in root Na +/K + ratio. The reductions in organic solutes concentrations were quite small, especially in the older leaves. A lower toxic ion accumulation during salt stress was related to salt tolerance and to seedling growth during salt recovery phase. On the contrary, higher leaf organic solute accumulation during salt stress was not related nor to salt tolerance nor to seedling recovery after salt stress relief. So, the high capacity of sorghum seedlings to recover after salt stress relief appears to be related to an adequate partition of carbon between shoots and roots and to changes in absorption, transport and re-translocation of salts.

Agar 배지를 이용한 건조 및 염 처리에 대한 벼 식물체의 근계 변화

본 실험은 고체배지를 이용한 새로운 실험방법을 이용하여 건조 및 염 스트레스에 대한 식물체의 형태학적인 특성을 뿌리신장률, 근단구조, 물질생산 등의 측면에서 조사하였다. PEG 및 NaCl 처리조건에서 처리 농도가 증가할수록 벼 식물체의 뿌리신장이 현저하게 저하되었으며, PEC 및 NaCl 처리에 따른 벼 식물체의 뿌리는 methyl-lignin 축적에 의한 리그닌화가 진행되었으며, 수분결핍을 극복하려는 기작으로 표피세포를 변형시킨 근모의 발생이 관찰되었다. 또한 PEG 및 NaCl 처리에 의한 벼 식물체의 지상부와 지하부의 건물 생산량의 현저한 감소는 지상부보다 지하부에서 뚜렷하였으며, 그 결과 PEG 및 NaCl 처 처리농도를 증가시킴에 따라 TR율의 증가를 보였다. 상기의 결과로부터 건조 및 염 처리를 한 고체배지를 이용함으로써 벼의 경우 스트레스 처리 전 약 2주간 유묘를 생육시키는 양액재배에 비해 발아기의 각종 스트레스에 대한 식물체 반응의 관찰과 내성 특성 검정에 유용할 것으로 사료된다. This study was investigated the changes of root length, tissue structure of root tip, and dry matter production of a Dongjinbyeo (DJ) cultivar subjected to 0.4 % agar medium with various concentration of NaCl (salt stress)- and polyethylene glycol 6000 (PEG, drought stress). Root length and dry weight of DJ plant were declined along the high concentration of PEG and NaCl in rice plants. To elucidate the changes of tissue structure in root tip to PEG- and NaCl-treatments, we examined the microscopic observation of root tip in NaCl- and PEG-treated rice plants using Toluidine blue O. By Toluidine blue O staining, methyl-lignin accumulation was found in the epidermis and outer cortex of the elongation zone at an early stage of PEG treatment, whereas was found only the outer cortex of the elongation zone of NaCl-treated root tip. The epidermis of NaCl-treated root tip became soften instead of methyl-lignin accumulation. TR ratio was increased along the high concentration in PEG- and NaCl-treated rice plant as a result of inhibited root elongation under PEG- and NaCl-treatment. From these morphological changes in root stimulated by drought and salt stress, we suggest that agar medium is useful to identify tolerant variety in germination stage under stressful environments.

Transformation of strawberry (Fragaria ananassa Duch.) with late embryogenesis abundant protein gene

SummaryCalli from anthers of strawberry (Fragaria ananassa Duch.), Toyonaka, were induced on MS medium plus 6-benzylamino-purine and naphthaleneacetic acid and transformed by particle bombardment with plasmid pBY520 containing late embryogenesis abundant protein gene, LEA3, from barley (Hordeum vulgare L.). Hybridization signals were detected by DNA dot blot analysis using a probe labelled with digoxigenin; it indicated foreign gene integration into the strawberry genome. The difference in salt tolerance between transgenic strawberry and controls was proved by salt stress test. Under 50 mmol l–1 and 100 mmol l–1 NaCl salt stress conditions, the wilting rates of controls were 62.2% and 96.0% respectively, compared with 18.6% and 42.8% for transgenic shoots. The results showed that the salt tolerance of the transgenic strawberry had been increased.

Salt Stress Induced Changes in Growth and Enzyme Activities in Germinating Phaseolus Mungo Seeds

NaCl salt stress induced changes in growth and enzyme activities in blackgram (Phaseolus mungo L.) seeds during germination were studied. A decrease in germination percentage, root length, shoot length, and fresh mass was noticed with an increase in NaCl concentration. With the increase in NaCl concentration and duration of stress proline content increased and catalase (CAT), peroxidase (POX) and polyphenol oxidase (PPO) activities decreased.

Salinity-induced effects on nitrogen assimilation related to growth in cowpea plants

This study was carried out to establish relationships between nitrate and ammonia assimilation and growth of cowpea ( Vigna unguiculata (L.) Walp) plants when exposed to NaCl-salinity. Cowpea plants were initially pre-acclimated under a mild NaCl-stress (50 mol m −3) during 8 days in order to induce salt acclimation. Subsequently, pre-acclimated and non-acclimated plants received a NaCl-osmotic shock (100 mol m −3) in the nutrient solution for 4 days. Although pre-acclimated plants exhibited lower NO 3 − uptake rate, in situ nitrate reduction, nitrate reductase (NR) activity, and shoot growth, they did not show alterations in these parameters, expressed as % of control, during the time-course experiment. These data suggest a salt adaptative response to a mild NaCl-salt stress. In contrast, addition of high level of NaCl (100 mol m −3) induced a steady decrease in nitrate uptake and assimilation parallel to a reduction in the shoot growth, particularly when the salt-shock was applied on the non-acclimated plants. On the other hand, the leaf glutamine synthetase activity, free amino acids and proline concentration showed a slight increase in all of salt treatments. The leaf soluble protein was slightly reduced by salt treatments during the short-term exposure. Moreover, the plants pre-acclimated with NaCl exhibited lower concentrations of protein and amino acids when compared with non-acclimated plants. Our study indicates that the regulation processes of N acquisition and growth of cowpea plants do operate at the whole plant level resulting in N homeostasis, especially in plants exposed to a mild-salt stress. Furthermore, the nitrate uptake and leaf-NR activity are more limiting for shoot growth than the primary ammonia assimilation from the glutamine synthetase.

Root growth and lignification of two wheat species differing in their sensitivity to NaCl, in response to salt stress

Application of a 100-mM NaCl salt stress to wheat seedlings of a salt-tolerant ( Triticum durum var. Ben Béchir) and a salt-sensitive ( Triticum aestivum var. Tanit) species decreases the fresh and dry weights of roots especially in the salt-sensitive species, and slightly increases the ratio of dry to fresh weight, especially in the salt-resistant species. All peroxidase activities are increased by salt stress, the water-soluble peroxidase activity being increased much more in the salt-sensitive than in the salt-tolerant species, while the opposite result is observed with the cell-wall peroxidase activity. Some water-soluble peroxidases have been hypothesised to have auxin oxidase activity (which might explain the effect observed on the root biomass), while the cell-wall peroxidases would be involved in lignification. Histochemical observation confirms a more intense lignification in the root cells of the salt-tolerant species compared to the sensitive species, under the effect of NaCl.

Response of two strains of Nostoc muscorum to metal stress and salinity

SummaryTwo strains of a cyanobacterium Nostoc muscorum, wild‐type N. muscorum (Cds) and an isolate having resistance to the heavy metal cadmium (Cdr), were selected for characterisation of their growth potential and physiological assays in certain defined stress environments.The chosen determinants were copper (heavy metal) and NaCl (salt stress). The observations on growth, heterocyst frequency, chlorophyll and nucleic acid contents, photosynthetic O2 evolution, 14C incorporation and acetylene reduction suggested that the strain Cdr was also resistant to copper. This strain, however, was found to be more sensitive to NaCl in comparison to its wild‐type counterpart. NaCl was found to enhance sugar accumulation in Cds and was more inhibitory to acetylene reduction rates than to the photosynthetic activities. The interaction between Cu and NaCl appeared to be antagonistic as the depression of growth and physiological activities by a mixture of the two was lesser than that caused by either of these. These observations form the first report on the response of a metal resistant strain of cyanobacterium to salinity.

Influence of host cultivars and Bradyrhizobium strains on the growth and symbiotic performance of soybean under salt stress

This paper examines the importance of salt tolerance of host cultivars, Bradyrhizobium strains, and host-Bradyrhizobium combinations on the symbiotic nitrogen fixation potential of soybean under NaCl and KCl salt stress. Plants were grown in a soil medium, and the experiments were conducted under controlled environment growth room conditions. Bradyrhizobium growth was examined in yeast-mannitol broth andB. japonicum strains tolerant of NaCl and KCl (80 mM) stress were identified. Soybean cultivar Williams, which was sensitive to salt stress, performed poorly both in growth and symbiotic nitrogen fixation, irrespective of whether it was matched with a tolerant or sensitive Bradyrhizobium strain. Tolerant cultivar Manchu sustained nodulation and nitrogen fixation, irrespective of whether it was matched with a tolerant or sensitive Bradyrhizobium strain. Evidence presented here suggests a need, first to select soybean cultivars that are tolerant to salt stress, and then to match them with tolerant and effective Bradyrhizobium strains.

Survival percentage, photosynthetic abilities and growth characters of two indica rice (Oryza sativa L. spp. indica) cultivars in response to iso-osmotic stress

The aim of this study was to investigate pigment degradation, chlorophyll fluorescence diminution, photosynthetic ability and growth reduction in two rice cultivars, in response to either iso-osmotic salt stress or water-deficit stress. Seedlings of rice cultivars RD6 and KDML105 were photo-autotrophically grown in MS media and subsequently exposed to –0.23 (control), –0.40 or –0.67 MPa iso-osmotic NaCl (salt stress) or mannitol (water-deficit stress) for 14 days. The survival percentage of the two rice cultivars reduced dramatically when subjected to –0.67 MPa NaCl treatment. Chlorophyll a (Chla), chlorophyll b (Chlb), total carotenoids (Cx+c), maximum quantum yield of PSII (Fv/Fm) and photon yield of PSII (ΦPSII) in the stressed seedlings were significantly lower when compared to seedlings in the control group (without mannitol or NaCl), leading to low net-photosynthetic rate (Pn) and growth reduction. In addition, the growth characters of plantlets in the salt stress conditions were more sharply reduced, and the physiological changes greater than those in water-deficit stress conditions. On the other hand, non-photochemical quenching in the leaves of stressed plantlets increased significantly, especially in response to iso-osmotic salt stress. In the present study, overall growth performance and physiological characters of KDML105 grown under iso-osmotic stress were better than those of RD6.