30份红三叶种质资源耐铜性综合评价

Comprehensive evaluation of copper tolerance of 30 germplasm resources of red clover(Trifolium pratense)

为评价红三叶种质耐铜能力强弱,筛选出优异种质材料,以30份国内外红三叶材料为对象,研究其萌发期和幼苗生长阶段Cu^(2+)胁迫下的生长发育特性,并采用隶属函数法对红三叶耐铜性进行综合评价。结果表明:随着Cu^(2+)胁迫浓度的增加,红三叶发芽率逐渐降低,胚根变短,变粗;胚根在Cu^(2+)浓度为0.5 mmol·L^(-1)下长度为对照的40%~69%,在Cu^(2+)浓度为8.0 mmol·L^(-1)时停止生长,而发芽率在Cu^(2+)浓度为8.0 mmol·L^(-1)时为对照的61%~93%,相对于发芽率,胚根对Cu^(2+)胁迫更为敏感。红三叶幼苗能够耐受20 mmol·L^(-1)的Cu^(2+)胁迫,但其地上生物量、地下生物量、根总长度、根尖数以及根体积均显著降低。不同浓度间红三叶各性状差异显著(P<0.05),且萌发期(0.5 mmol·L^(-1))和苗期(20 mmol·L^(-1))不同红三叶材料间同一性状亦存在显著差异性(P<0.05);胚根长度与胚根直径、地上生物量与地下生物量、地下生物量与根冠比、根总长度和根尖数等性状之间具有显著相关性(P<0.01);依据最小二乘法原理,建立了以胚根长度、幼苗存活率、地下生物量和根总长度4个关键指标为因子的预测模型,其预测值与综合评价值显著相关(R^(2)=0.977)。综合评价结果表明,材料CF022167、CF022178及CF022232具有较高的铜胁迫耐受性,可作为红三叶耐铜性新品种选育的基础材料或在生产中直接利用。

The aim of this study was to evaluate the copper(Cu^(2+))tolerance of different red clover germplasm lines and select the tolerant lines.To this end,we evaluated the growth characteristics of 30 red clover germplasm lines under Cu^(2+)stress at the germination and seedling stages.A subordinate function method was used to evaluate copper tolerance.It was found that,as the Cu^(2+)concentration increased,the germination rate gradually decreased,and the radicle became shorter and thicker.Compared with the germination rate,radicle growth was more sensitive to Cu^(2+)stress.At a Cu^(2+)concentration of 0.5 mmol·L^(-1),the radicle was 40%-69%of the length of that in the control.At a Cu^(2+)concentration of 8.0 mmol·L^(-1),the radicle stopped growing while the germination rate was 61%-93%of that in the control.Red clover seedlings could tolerate Cu^(2+)concentrations up to 20 mmol·L^(-1),however,the aboveground biomass,underground biomass,total root length,root tip number,and root volume were significantly reduced compared with their respective values in the control.There were also significant differences among different Cu^(2+)concentrations in terms of their effects on other major traits of red clover(P<0.05).The values for each trait differed significantly among red clover germplasm materials at the germination stage(treated with Cu^(2+)at 0.5 mmol·L^(-1))and seedling stage(treated with Cu^(2+)at 20 mmol·L^(-1))(P<0.05).The correlations between radicle length and radicle diameter,aboveground biomass and underground biomass,underground biomass and root:shoot ratio,and total root length and root tip number were extremely significant(P<0.01).A least squares model to estimate the Cu^(2+)tolerance of each clover germplasm line was established using four factors:radicle length,seedling survival rate,underground biomass,and total root length.The value predicted using this model was significantly correlated with the multivariate evaluation value(P<0.01).According to the results of the multivariate evaluation,CF022167,CF022178 and CF022232 were identified as the most Cu^(2+)-tolerant lines.These lines are recommended for use as breeding materials to produce new Cu^(2+)-tolerant varieties or directly utilized in production.