| Rice (Oryza sativa) is one of the most important crops in China. Heilongjiang Province is the main cultivation area of japonia(Oryza sativa Linn, subsp. japonica Kato). The process of urbanization and industrialization induced a large area of soil salinization. Soil salinization is a kind of abiotic stress which always restricts rice production.Therefore, it is very important to breed rice varieies with saline-alkaine tolerance and stable yield. In this study, different concentration levels of NaHCO3solution were used to simulate the sodic soil in Heilongjiang Province and80japonia materials from three provinces of northeast were used to investigate the saline-alkaine tolerance related morphological indexes, growth and development conditions, physiological and biochemical reactions of defferent cultivars under the saline-alkaine stress and normal condition in order to identify and evaluate the rice saline-alkaine tolerance at germination and seedling stages. F2:3lines derived from the cross between Dongnong425, which was a high yeild and quality variety, and Changbai10, which has strong tolerance to saline-alkaline, were used as a mapping population for constructing a genetic map and mapping QTLs related to saline-alkaline tolerance. The main conclusions of this study are as follows:1. Germination rate, seedling height, root number, root length, dry weight of plant decreased with the increasing concentration level of saline-alkaline stress. The difference between varieties and treatments on the germination rate, seedling heigh, dry weight of plant were significant. Root number, root length showed significant difference between treatments.23cultivars (lines) of80tested japonia rice materials were tolerant to saline-alkaline stress of varying degrees at the gemination stage, and the range of Subordinate function value was0.61to1.00.2. Plant height, leaf area, green leaves rate, and the chlorophyll concents decreased with the increasing concentration level of saline-alkaline stress, but the MDA and proline concents increased correspondingly with increasing concentration level of saline-alkaline stress. The difference between varieties and treatments on plant height, leaf area, green leaves rate, the concents of chlorophyll, MDA and proline were significant.16cultivars (lines) of80tested japonia materials were tolerant to saline-alkaline stress of varying degrees at the the seedling stage, and the range of subordinate function value was0.61to0.80.3. The most appropriate concentration level of NaHCO3solution for evaluating saline-alkaline tolerance of tested materials were50mmol·L-1and75mmol·L-1at germination and seedling stage, respectively. The traits of F2:3lines including relative germination energy, relative germination rate, relative root number, relative root length, relative plant height, relative colepotile length, relative fresh weight at germination stage and saline-alkaline tolerance score at seedling stage showed normal distribution and performed observably transgressive effect. These traits can be used for saline-alkaline tolerance related QTLs detection.4.600SSR markers were used to analyze the polymorphism between parents (Dongnong425and Changbai10).120polymorphic markers were detected between F2:3lines. Of them,84markers were used to construct genetic map. The linkage map was about1414.8cM and covered12chromosomes (linkage groups) of rice The average distance between molecular markers was16.84cM.5. QTLs controlling saline-alkaline tolerance related traits of the germination and the seedling stages were detected based on the composite interval mapping method. The results were as follows:(1) Four QTLs for RGE under saline-alkaline stress were mapped on chromosome1,6and8, which explained7.23%～27.95%of the total phenotypic variance. The QTL on chromosome8located between RM515and RM483explained the biggest phenotypic variance, showed negative additive effect. It indicated that the positive synergism allele was from Dongnong425.(2) Three QTLs for RGR under saline-alkaline stress were located on chromosome3,6and9, which explained6.37%～17.55%of the total phenotypic variance. The QTL on chromosome9located between RM201and RM285explained the biggest phenotypic variance, showed positive additive effect. It indicated that the positive synergism allele was from Changbai10.(3) One QTL for RRN under saline-alkaline stress was detected on chromosome7located between RM201and RM285, explaining6.37%～17.55%of the total phenotypic variance, showed positive additive effect, Positive synergism allele was from Changbai10.(4) Four QTLs for RRL under saline-alkaline stress were detected on chromosome2,6and12, explaining10.54%～33.56%of the total phenotypic variance. The QTL on chromosome2located between RM1342and RM1347explained the biggest phenotypic variance, showed positive additive effect, Positive synergism allele was from Changbai10.(5) Four QTLs for RPH under saline-alkaline stress were detected on chromosome1,5,6and8, explaining5.5%～13.71%of the total phenotypic variance. The QTL on chromosome6located between RM1340and RM454explained the biggest phenotypic variance, showed positive additive effect. Positive synergism allele was from Changbai10.(6) Five QTLs for RCL under saline-alkaline stress were detected on chromosome2,3,10and11, explaining5.78%～13.89%of the total phenotypic variance. The QTL on chromosome2located between RM1342and RM1347explained the biggest phenotypic variance, showed positive additive effect. Positive synergism allele was from Changbai10.(7) Two QTLs for RFW under saline-alkaline stress were detected on chromosome6and8, explaining5.78%and13.89%of the total phenotypic variance. It showed positive additive effect. Positive synergism allele was from Changbai10.(8) Six QTLs for STS under saline-alkaline stress were detected on chromosome1,4,5and6, explaining5.9%～23.89%of the total phenotypic variance. The QTL on chromosome2located between RM471and RM335explained the biggest phenotypic variance, showed positive additive effect. Positive synergism allele was from Changbai10. |
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