干旱胁迫对三裂叶豚草种子萌发及幼根生长的影响

Effects of Drought Stress on Seed Germination and Young Root Growth of Ambrosia trifida L.

研究三裂叶豚草种子萌发及幼根生长对干旱胁迫的响应,旨在为科学防控提供依据.以三裂叶豚草种子为材料,用不同质量分数聚乙二醇(PEG)溶液处理,以蒸馏水处理为对照(CK),设置5%、10%、15%、20%、25%5个质量分数梯度代表轻度、中度、重度、极度、极重度干旱,测定日相对发芽率、发芽率、发芽势、发芽指数和活力指数,分析三裂叶豚草种子萌发情况;测定根表面积、投影面积、体积、根长、根尖数及根分叉数,分析幼苗根生长情况;统计种子恢复萌发情况.结果表明:无干旱胁迫的三裂叶豚草种子各萌发指标最高,干旱胁迫强度增加,种子各萌发指标减小,干旱胁迫强度极大时,种子不发芽.与CK相比,轻度干旱胁迫和重度干旱胁迫对三裂叶豚草根长影响不显著,但会促进侧根与不定根生长;中度干旱胁迫会使根长显著变短,并且会抑制侧根与不定根数量的增加.三裂叶豚草种子在PEG质量分数为24.69%的干旱时不发芽.种子在极重度干旱下不萌发,个别种子在极度干旱下不萌发,但当水分充足时,种子依然具有萌发能力.建议在三裂叶豚草种子尚未成熟前,人工拔除植株,或在入侵地种植耐旱强、生长快、根系发达、竞争性强的植物,以控制三裂叶豚草的生长发育.

The response of seed germination and young root growth of Ambrosia trifida to drought stress were studied,which provide basis for its scientific prevention and control.Ambrosia trifida seeds,as research materials,were treated with polyethylene glycol(PEG)solution with different mass fractions.Distilled water was used as the control group(CK),and five mass fraction gradient groups of 5%,10%,15%,20%and 25%were set to represent the degree of mild,moderate,severe,extreme and extremely severe drought respectively.The daily relative germination rate,the germination rate,germination potential,germination index and vigor index were used to analyze the seed germination of Ambrosia trifida;The root surface area,projected area,volume,root length,root tip number and root bifurcation number were measured,and the root growth of seedlings was analyzed;The recovery and germination of seeds were measured.The results showed that the seed germination index of Ambrosia trifida without drought stress was the highest,and the seed germination index decreased while the intensity of drought stress increased.When the intensity of drought stress was maximum,the seed of Ambrosia trifida did not germinate.Compared with CK,mild drought stress and severe drought stress had no significant effect on the root length of Ambrosia trifida,but could promote the growth of lateral and adventitious roots;Moderate drought stress can significantly shorten the root length and inhibit the increase of the number of lateral and adventitious roots.A.trifida seeds did not germinate under drought conditions with PEG mass fraction of 24.69%.Seeds did not germinate under extreme drought,and individual seeds did not germinate under extreme drought.The seeds still had the ability to germinate while the water condition was sufficient.The research results provide a basis for the control of Ambrosia trifida.In conclusion,it is suggested to manually pull out the plants before the Ambrosia trifida seeds will be mature,or cultivate plants with strong drought tolerance,fast growth,developed roots and strong competitiveness in the invasion area of Ambrosia trifida,so as to control the growth and development of Ambrosia trifida.