PEG胁迫下旱地油菜绿肥苗期抗旱性筛选和评价

Evaluation of drought resistance of Brassica green manure crops using seedling growth indices

【目的】研究苗期抗旱能力突出的油菜绿肥种子萌发特性和生理特征,为筛选适宜于黄土高原旱作区种植的油菜绿肥品种提供可靠的方法及建议。【方法】采集了30份油菜绿肥品种进行室内发芽试验,设正常水分对照和以10%聚乙二醇(polyethylene glycol 6000,PEG-6000)高渗溶液人工模拟的干旱胁迫处理。分析苗期的根长、芽长、鲜重、根芽比、萌发指数、发芽指数和相对活力指数的变化,并采用隶属函数、灰色关联度分析、综合抗旱指数和系统聚类分析相结合的方法,对不同油菜绿肥品种苗期抗旱能力进行综合评价,同时分析三类油菜绿肥抗旱群体[抗旱能力强(HR),抗旱能力中等(MR),抗旱能力弱(LR)]各抗旱指标的差异情况。【结果】与对照相比,干旱胁迫处理油菜绿肥苗期的根长和根芽比分别平均增加了52.7%和96.6%(P<0.05),芽长和单株鲜重分别平均降低了21.4%和36.6%(P<0.05),而苗期发芽率有增加的趋势(P>0.05)。参试油菜绿肥种子的萌发特性与综合抗旱指数的关联度均在70%以上,其密切程度顺序为:萌发指数>相对活力指数>根长>芽长>发芽指数>鲜重>根芽比。对参试30份绿肥品种的加权抗旱指数进行聚类分析,在欧式距离为5时,17份参试油菜绿肥归为强抗旱品种,8份归为中等抗旱品种,5份归为弱抗旱品种。3类抗旱品种芽长无显著差异,高抗旱性品种的发芽率、根长、单株鲜重和根芽比显著高于中等和弱抗旱性品种(P<0.05)。【结论】油菜绿肥种子萌发指数、相对活力指数和根长与其综合抗旱指数关联较为密切,而鲜重和根芽比与其关联度较弱。抗旱能力较强的品种通过提高发芽率和根芽比,增加根系长度来抵御干旱胁迫。30个供试绿肥油菜品种中有17个品种,因其苗期较强的萌发特性和抗旱能力,适宜在黄土高原旱作区推广种植。

【Objectives】The purpose of this study was to clarify the seed germination and physiological characteristics of Brassica green manure(GM)seeds with a strong ability to resist drought.We aim to establish reliable methods and suggestions for screening Brassica GM varieties suitable for cultivation in dryland conditions of the Loess Plateau of China.【Methods】We collected 30 Brassica green manure(GM)varieties for the indoor germination experiment with the control(water)and drought stress[10%polyethylene glycol(PEG)-6000 solution]treatments.The changes in root length,bud length,fresh weight,root:bud length ratio(R:B ratio),germination drought resistance index(GDI),germination index(GI),and relative vigor index(VI)at the seedling stage were analyzed.The tested Brassica GM seeds’drought resistance ability was comprehensively evaluated by combining the subordinate function,grey correlation analysis,comprehensive drought resistance index(CDI),and systematic cluster analysis method.Three Brassica GM drought-resistant groups(HR-high drought resistant,MR-medium drought resistant,LR-low drought resistant)were obtained by analyzing the differences in drought resistance indexes.【Results】Compared with the control treatment,PEG-6000 simulated drought stress(P<0.05)increased root length and root:bud length ratio at the seedling stage by 52.7%and 96.6%,but decreased the bud length and fresh weight by 21.4%and 36.6%,respectively.Additionally,there was a slight increase in the germination rate of Brassica GM varieties at the seedling stage(P>0.05).The correlations between the seedling germination characteristics of Brassica GM varieties and CDI were all above 70%,and the order of closeness was:GDI>VI>root length>bud length>GI>fresh weight>R:B ratio.Cluster analysis was carried out on the weighted drought tolerance index(WDTI)of 30 Brassica GM varieties.At Euclidean distance of 5,17 Brassica GM varieties were classified as the HR group,8 as the MR group,and 5 as the LR group.There was no significant difference in bud length among the three drought-resistant groups.The germination rate,root length,fresh weight per plant,and R:B ratio of the HR group were(P<0.05)higher than MR and LR groups at the seedling stage.【Conclusions】GDI,VI,and root length of the 30 Brassica GM seeds were closely related to CDI.However,there were weak relationships between the fresh weight,R:B ratio and CDI.The Brassica GM varieties with strong drought resistance ability can efficiently resist drought stress by increasing the germination rates,R:B ratio,and root length.17 of the 30 tested Brassica GM varieties are suitable for planting in the dry-land regions of the Loess Plateau,due to strong germination and drought resistance abilities at the seedling stage.