Abstract:

【Objective】Soil salinity is one of the major abiotic stresses affecting rice growth and production. Salt resistance identification at germination stage, indices screening, and cultivar breeding of rice germplasm resources are important for rice production.【Method】Seeds of sixty-four japonica rice germplasm accessions germinated in the 125 mmol L^-1 NaCl solution. On the third day after salt stress, germination number of the seeds was measured. After salt stress for five and ten days, germination number, shoot length and root length were measured and then the relative shoot length, relative root length, relative germination potential, relative germination rate, relative salt damage rate, germination index and vigor index were calculated. Multiple statistical methods were used to comprehensively evaluate the salt tolerance of 64 rice japonica germplasm and the germination characteristics of typical salt-tolerant and salt-sensitive rice germplasm under salt stress were analyzed. 【Result】The relative salt damage rate was significantly negatively correlated with relative root length, relative germination potential, relative germination rate, germination index and vigor index. Except for relative shoot length, these six indexes were significantly correlated with each other. Through cluster analysis, 64 japonica rice germplasm were divided into four groups. The group Ⅰ and Ⅳ were typical salt-sensitive and salt-tolerant germplasm, respectively. The group Ⅱ was mainly composed of low salt-resistant rice and the group Ⅲ was moderately salt-tolerant. With the principal component analysis these seven single indexes could be converted to three principal components. An objective comprehensive evaluation value (D value) of salt tolerance was obtained using membership function with index weight method. The five highest and lowest D value germplasm resources were selected to carry on significance analysis. The results showed that except for relative shoot length, all of these seven indexes measured after stress for five and ten days were significantly different from the two types. 【Conclusion】Rice was sensitive to salt stress at germination stage and there were significant differences between different germplasm. Using stepwise regression and principal component analysis, germination index, relative root length and relative salt damage rate were selected as the key indexes for the rapid identification of salt tolerance of rice germplasm. If multivariate statistical method was used, the reliability will be improved.

Key words: rice, germplasm resource, salt tolerance at germination stage, principal component analysis, comprehensive evaluation

摘要：

【目的】 土壤盐渍化是危害水稻生产的重要非生物胁迫之一。鉴定水稻种质资源发芽期耐盐性,筛选耐盐指标,培育耐盐品种,对水稻生产的发展具有重要意义。【方法】 利用125 mmol/L NaCl溶液对64份粳稻种质资源进行盐胁迫,于胁迫后3 d测定发芽数;胁迫5 d、10 d后,测定发芽数、芽长和根长,并计算相对芽长、根长、发芽势、发芽率、盐害率,发芽指数和活力指数。运用多种统计学方法对各种质资源的芽期耐盐性进行综合评价,分析典型耐盐和盐敏感种质盐胁迫条件下的发芽特征。【结果】 相对盐害率与相对根长、相对发芽势、相对发芽率、发芽指数和活力指数均极显著负相关;除相对芽长外各指标间的相关性均达到极显著水平。通过聚类分析将64份粳稻种质资源划分成4个类群。第Ⅰ、Ⅳ类群分别为典型的盐敏感和耐盐类群,第Ⅱ类群为弱耐盐种质为主的混合类群,第Ⅲ类群主要由耐盐种质组成。通过主成分分析将7个评价指标转换为3个主成分,应用隶属函数和权重,获得了客观评价粳稻种质资源耐盐性的综合评价值 D。分别选取D值最高和最低的5份种质资源进行芽期耐盐指标的差异显著性分析,结果表明,两组种质资源盐胁迫5 d的各评价指标差异均达到极显著水平,10 d的评价指标除相对芽长外,均达到了显著差异水平。【结论】 水稻芽期对盐胁迫较为敏感,且耐盐性不同的种质间差异显著。利用逐步回归和主成分分析获得发芽指数、相对根长和相对盐害率3个指标,可作为快速鉴定粳稻种质资源芽期耐盐性的重要指标,若采用多元统计方法评价可靠性更高。

关键词: 水稻, 种质资源, 芽期耐盐性, 主成分分析, 综合评价