Identification Of Salt Tolerance Of Japonica Rice Germplasm Resources At Different Growth Period

In order to identify the salt tolerance and physiological responses of 64 japonica rice germplasm resources under salt stress condition, the salt tolerance were evaluated at the germination stage, tillering stage, initial heading stage and mature stage. Salt injury situation of each period were recorded. The length of bud, root length, relative germination rate, relative germination potential, germination index, vigor index and relative salt damage rate of each rice germplasm at the germination stage were measured. The seedling survival rate of each rice germplasm was recorded 2 weeks after transplanting and the number of tillers at the tillering stage, leaf MDA content, membrane permeability, leaf chlorophyll, soluble sugar content at initial heading stage were measured. The number of spike per plant, panicle length, grain number per plant,1000 grain weight, yield per spike, yield per plant and plant height at the mature stage were measured and the effects of salt stress on different rice varieties at different growth stages were analyzed. By using principal component analysis and membership function, the salt tolerance of 64 japonica rice germplasm resources was evaluated comprehensively. The results showed that:1. There were different degrees of correlation among different indexes at the germination stage of japonica rice germplasm resources. Based on the principal component analysis,4 representative germination indexes were selected, namely:relative germination potential, relative germination rate, germination index and relative salt damage rate. According to the comprehensive evaluation of D value,5 salt resistant germplasm resources were screened out, including Daniela, Gostima, Hrborio Cyauco, Arborio and Rossi. Based on cluster analysis and comprehensive evaluation of D value,64 japonica rice germplasm resources were divided into 4 groups. The average value of the salt tolerant indexes of five low D value germplasm resources and 5 high D value germplasm resources were showed significant difference at 5d after salt stress. There was no significant difference in the relative shoot length among these ten rice germplasm, but the relative root length, relative germination rate and relative salt damage rate showed significant difference between the two kinds of rice germplasm after lOd treatment.2. According to the seedling survival rate and tiller number,64 japonica rice germplasm resources were divided into salt tolerant group, moderate salt tolerant group and salt sensitive group. Based on the comprehensive analysis of the survival rate and tiller number,5 salt tolerant germplasm resources were obtained, such as Jiahe 1, Bertone, ZhongHua 9, LiaoFeng 8 and Luwei rice.3. At the initial heading stage, according to the survival rate five salt resistant germplasm and five salt sensitive germplasm were selected. The MDA content, chlorophyll content, relative conductivity, soluble sugar content of leaves were measured. The effects of salt stress on the above 4 physiological indexes of the same germplasm group were different and the chlorophyll content in salt group was 49.2, higher than that of salt sensitive group.4. There was a significant difference in the indexes of different germplasm of rice in the same year. There were also different degrees of differences in the same germplasm in different year. According to factor analysis, the evaluation indexes of salt tolerance in mature stage were selected. Namely, Single spike yield, yield per plant, grain number per ear and ear length. Through comprehensive analysis, five high salt resistant germplasm were selected, namely, Galhardo, Bertone, Amepukahmib, Rossi and Hungarian NO.1.5. A comprehensive evaluation of different growth period of rice was developed. The relationship between soluble sugar and yield per plant was negatively correlated and a significant negative correlation was observed between the relative electrical conductivity and the yield per plant. Based on the comprehensive ranking of the typical salt tolerance related indexes in each growth period,5 salt tolerant germplasm were detected. Such as Galhardo, Bertone, Kele (34978), Arborio and Banat 725, which were suitable for cultivate in saline alkali soils in north of china and could be used as salt tolerant parents for the selection and breeding of new salt tolerant varieties.