干旱胁迫对万寿菊种子萌发及幼苗生理特性的影响

Effects of drought stress on seed germination and seedling physiological characteristics of Tagetes erecta

摘要:

【目的】 探索在干旱胁迫下万寿菊（Tagetes erecta）种子萌发及幼苗生理特性。【方法】 设置不同浓度聚乙二醇（PEG）（2%、4%、6%、8%和10%）模拟干旱胁迫，利用发芽盒发芽研究干旱胁迫下万寿菊种子发芽率、发芽指数、活力指数和抗旱指数；采用盆栽试验研究自然干旱胁迫0~12 d对万寿菊幼苗形态指标（株高，地径）以及生理指标（含水量、膜透性，3种酶活性等）的影响。【结果】 随着PEG浓度增加，万寿菊种子发芽率、发芽指数、活力指数和抗旱指数逐渐降低；在PEG浓度为6%时，其种子发芽率、发芽指数、活力指数和抗旱指数显著下降（P＜0.05），较对照分别降低46%、14.45%、32.21%和 0. 713；随着自然干旱胁迫天数的增加，万寿菊幼苗株高和地径先增大后减小；叶片中脯氨酸和丙二醛含量呈上升趋势；可溶性蛋白含量先上升后下降；束缚水逐渐降低，自由水逐渐升高；叶绿素a，b和叶绿素总量先上升后降低；超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（Catalase，CAT）3 种酶活性随含水量先降低后升高，达到峰值之后开始下降。【结论】 PEG浓度小于6%万寿菊种子能正常萌发生长；土壤含水量大于50%万寿菊幼苗可以正常生长。

Abstract:

【Objective】 The aim of the study is to explore the seed germination and seedling physiological characteristics of Tagetes erecta under drought stress.【Method】 Different concentrations of polyethylene glycol （PEG） （2%，4%，6%，8% and 10%） were set to simulate drought stress. Germination rate，germination index，vitality index and drought resistance index of Marigold seeds under drought stress were studied by germinating box. Pot experiment was conducted to study the effects of natural drought stress from 0 d to 12 d on morphological indexes （plant height， ground diameter） and physiological indexes （water content，membrane permeability，three enzyme activities，etc.） of Marigold seedlings.【Result】 The experiments showed that the germination rate，germination index，vitality index and drought resistance index of T. erecta seeds decreased gradually with the increase of PEG concentration. When PEG concentration was 6%，the germination rate，germination index，vigor index and drought resistance index of the seeds were significantly decreased，which were 46%，14. 45%，32. 21% and 0. 713 lower than the control group，respectively（P＜0. 05）. With the increase of drought stress days，the seedling height and ground diameter of T. erecta seedlings increased first and then decreased，while the contents of proline and malondialdehyde in leaves of T. erecta seedlings showed an increasing trend. The content of soluble protein increased first and then decreased. The bound water gradually decreases and the free water gradually increases. The total amount of chlorophyll a，b and chlorophyll first increased and then decreased；The activities of superoxide dismutase （SOD），peroxidase （POD） and catalase （CAT） enzymes decreased first and then increased with water content，and then decreased after reaching the peak value.【Conclusion】 The seeds of T. erecta under the PEG concentration less than 6% could germinate normally. T. erecta seedlings could grow normally if the soil water content is greater than 50%.