薏苡种质资源苗期抗旱性鉴定及抗旱指标筛选

摘要

[目的]干旱是影响薏苡生产的重要非生物胁迫因素,鉴定薏苡种质资源的抗旱性,确定抗旱指标,筛选抗旱种质,促进薏苡产业发展.[方法]以50份薏苡种质为材料,设置正常供水和反复干旱2个处理,在旱棚内进行盆栽试验,测定干旱对幼苗存活率、株高、茎粗、叶长、叶宽、地上部鲜重、地上部干重、根长、根粗、根鲜重和根干重的影响;采用抗旱性度量值(D值)、综合抗旱系数(CDC值)、加权抗旱系数(WDC)、相关分析、频次分析、主成分分析、灰色关联度分析、隶属函数分析、聚类分析和逐步回归分析相结合的方法,对其进行苗期抗旱性鉴定及抗旱指标筛选.[结果]干旱胁迫对各指标均有极显著影响.相关分析表明,幼苗干旱存活率与茎粗、叶宽和根粗呈极显著正相关,与叶长、地上部鲜重、地上部干重、根长、根鲜重和根干重呈显著正相关,与株高呈不显著的正相关.频次分析表明,各指标对干旱胁迫反应的敏感程度依次为根干重、根鲜重、叶宽、根粗、根长、幼苗干旱存活率、地上部干重、茎粗、地上部鲜重、叶长和株高.主成分分析表明,6个主成分可代表薏苡抗旱性91.40％的原始数据信息量.基于D值、CDC值和WDC值的供试薏苡种质抗旱性排序相近.灰色关联度分析表明,各指标DC值与D值间的关联度大小依次为根干重、叶宽、根鲜重、茎粗、根粗、幼苗干旱存活率、根长、株高、地上部鲜重、地上部干重、叶长,这与各指标DC值与WDC值的密切程度基本吻合.根据D值进行聚类分析,可将供试薏苡种质划分为5个抗旱级别,其中Ⅰ级3份、Ⅱ级1 7份、Ⅲ级9份、Ⅳ级20份、Ⅴ级1份.除叶长、地上部鲜重、地上部干重和根干重外,其余指标的隶属函数值、CDC值、D值和WDC值均随抗旱级别的升高而增大.逐步回归分析表明,与D值密切相关的指标有幼苗干旱存活率、株高、叶宽、根长和根鲜重.[结论]苗期抗旱性强的薏苡种质yy18-1、yy14-3和yy13-1,可作为薏苡抗旱育种、抗旱机理及干旱调控缓解机制研究材料.幼苗存活率、株高、叶宽、根长和根鲜重可作为评价薏苡种质资源苗期抗旱性的指标性状.%[Objective] Drought is the important abiotic stress factor for Job's tears production.Drought resistance identification,indices determination,and germplasms screening of Job's tears germplasm resources are important for Job's tears industrial development.[Method] The seedling drought survival rate,plant height,culm diameter,leaf length,leaf width,shoot fresh weight,shoot dry weight,root length,root diameter,root fresh weight,and root dry weight of 50 Job's tears germplasms were measured at the normal water supply and repeated drought treatments in pot experiments in rainprotection shed.Drought resistance comprehensive evaluation value (D value),comprehensive drought resistance coefficient (CDC value),weight drought resistance coefficient (WDC value),correlation analysis,frequency analysis,principal component analysis,grey relational analysis,subordinate function analysis,clustering analysis,and stepwise regression analysis were used to identify the drought resistance and screen drought resistance indices of tested Job's tears germplasms at seedling stage.[Result] Drought stress had significant effects on all indices.Correlation analysis showed that the seedling drought survival rate was significantly and positively correlated with culm diameter,leaf width,root diameter,leaf length,shoot fresh weight,shoot dry weight,root length,root fresh weight,and root dry weight,but not with plant height.Frequency analysis showed that the sensitive degrees of all indices response to drought stress in turn for root dry weight,root fresh weight,leaf width,root diameter,leaf length,seedling drought survival rate,shoot dry weight,culm diameter,shoot fresh weight,leaf length,and plant height.Principal component analysis showed that 6 principal components could represent 91.40％ of the original data information of Job's tears drought resistance.The ranks of drought resistance of tested Job's tears germplasms based on the D value,CDC value,and WDC value were similar.Grey relational analysis showed that the correlation degree between DC value of all indices and D value in turn for root dry weight,leaf width,root fresh weight,culm diameter,root diameter,seedling drought survival rate,root length,plant height,shoot fresh weight,shoot dry weight,and leaf length,which was similar to the correlation degree between DC value of all indices and WDC value.According to D value clustering analysis,tested Job's tears germplasms were divided into 5 drought resistance grades,3 belonged to grade Ⅰ,17 belonged to grade Ⅱ,9 belonged to grade Ⅲ,20 belonged to grade Ⅳ,and 1 belonged to grade Ⅴ.The subordinate function values of tested indices except for leaf length,shoot fresh weight,shoot dry weight and root dry weight,CDC value,D value,and WDC value were increased with increase of drought resistance grades.Stepwise regression analysis showed that the seedling drought survival rate,plant height,leaf width,root length,and root fresh weight were closely related to the D value.[Conclusion] yy18-1,yy14-3,and yy13-1 were identified as drought resistance Job's tears germplasms at seedling stage,which could be used as materials for the researches on cultivar breeding,mechanism,and regulation and alleviation mechanism of drought resistance in Job's tears.The seedling drought survival rate,plant height,leaf width,root length,and root fresh weight could be used as the simple and intuitive identification indices of drought resistance in Job's tears germplasm resources at seedling stage.