以多年生草本黑麦草为对象,模拟喀斯特生境土壤特征设置浅而宽(Shallow and wide,SW:30×30×5 cm^3)和深而窄(Deep and narrow,DN:10×10×45 cm^3)两种土壤容器,以正常降水量为对照供水(W100%),设减水50%(W50%)和减水...以多年生草本黑麦草为对象,模拟喀斯特生境土壤特征设置浅而宽(Shallow and wide,SW:30×30×5 cm^3)和深而窄(Deep and narrow,DN:10×10×45 cm^3)两种土壤容器,以正常降水量为对照供水(W100%),设减水50%(W50%)和减水70%(W30%)共3种水分处理进行盆栽实验,探究了两种不同土壤生境中土壤水分变化对黑麦草生长及光合生理的影响,以进一步理解喀斯特地区植物的适应对策。结果显示:(1)SW生境对水分变化敏感,随供水减少土壤含水量显著下降。轻度减水下植物叶面积增大,光合速率提高,地上部分生长得到促进,但水分严重减少对其生长和光合生理有抑制作用,但地上质量分数和水分利用效率却显著升高;(2)DN生境保水能力较好,随供水减少土壤水分含量下降较为平缓。叶片相对含水量、气孔导度和比叶面积在各水分处理之间差异不显著,但严重减水条件下总生物量、地上质量分数和水分利用效率均有回升。研究表明:浅而宽生境中植物倾向于通过提高地上部分的生长,保持较高的光合速率,并向地上部分分配较多生物量来应对水分胁迫;而深而窄生境中植物会充分利用土壤空间条件,促进根系的生长来提高对水分的吸收,从而维持植物的生长。展开更多
Shallow soil with low water availability is the key limiting factor for plant growth and reproduction in vulnerable karst regions.Annual herbs are pioneers adapted to these areas;however,little is known about the resp...Shallow soil with low water availability is the key limiting factor for plant growth and reproduction in vulnerable karst regions.Annual herbs are pioneers adapted to these areas;however,little is known about the responses of their seeds and infructescence,and the germination of their offspring to these limited water and soil resources.In this study,we investigated how the seed and fruiting phenology plasticity and offspring seed germination rates of two annual Asteraceae herbs(Xanthium sibiricum and Bidens pilosa)respond to the harsh karst soil environment,by assessing the seed number,seed biomass and offspring seed germination rate.X.sibiricum and B.pilosa were grown under three soil thicknesses and three water availability levels in a full two-way randomized block design.The key results were as follows:(1)The number and biomass of progenies(infructescence and seeds)of X.sibiricum decreased with the decline of soil thickness and/or water availability(P<0.05).The infructescence and seed biomass of B.pilosa increased with the decline of water availability.(2)Seed quantity and seed biomass of X.sibiricum showed no correlation after their parents experienced resource reductions.A significant positive relationship between seed number and seed biomass was observed in B.pilosa(P<0.05).(3)The offspring seed germination rate of X.sibiricum did not change with the decrease of soil thickness under three levels of water treatment.However,the offspring seed germination rate of B.pilosa decreased significantly with the decrease of soil thickness under the control water level(P<0.05).The results show that X.sibiricum tends to improve its competitiveness by ensuring the quantity and quality of offspring in order to adapt to the shallow karst soils and dry karst habitats.In contrast,B.pilosa adapts to the unfavorable karst habitats by a risk-sharing strategy.B.pilosa produces more and bigger seeds to in an attempt to expand its survival range and escape from the unfavorable living environment,but this results in a lower seed number and germination rate of its progeny under the karst soil resource reduction.展开更多
文摘以多年生草本黑麦草为对象,模拟喀斯特生境土壤特征设置浅而宽(Shallow and wide,SW:30×30×5 cm^3)和深而窄(Deep and narrow,DN:10×10×45 cm^3)两种土壤容器,以正常降水量为对照供水(W100%),设减水50%(W50%)和减水70%(W30%)共3种水分处理进行盆栽实验,探究了两种不同土壤生境中土壤水分变化对黑麦草生长及光合生理的影响,以进一步理解喀斯特地区植物的适应对策。结果显示:(1)SW生境对水分变化敏感,随供水减少土壤含水量显著下降。轻度减水下植物叶面积增大,光合速率提高,地上部分生长得到促进,但水分严重减少对其生长和光合生理有抑制作用,但地上质量分数和水分利用效率却显著升高;(2)DN生境保水能力较好,随供水减少土壤水分含量下降较为平缓。叶片相对含水量、气孔导度和比叶面积在各水分处理之间差异不显著,但严重减水条件下总生物量、地上质量分数和水分利用效率均有回升。研究表明:浅而宽生境中植物倾向于通过提高地上部分的生长,保持较高的光合速率,并向地上部分分配较多生物量来应对水分胁迫;而深而窄生境中植物会充分利用土壤空间条件,促进根系的生长来提高对水分的吸收,从而维持植物的生长。
基金The Chongqing Natural Science Foundation(cstc2020jcyj-msxmX0244)The Special Funds for Basic Scientific Research in Central Universities(XDJK2020B037)The National Natural Science Foundation of China(31500399)。
文摘Shallow soil with low water availability is the key limiting factor for plant growth and reproduction in vulnerable karst regions.Annual herbs are pioneers adapted to these areas;however,little is known about the responses of their seeds and infructescence,and the germination of their offspring to these limited water and soil resources.In this study,we investigated how the seed and fruiting phenology plasticity and offspring seed germination rates of two annual Asteraceae herbs(Xanthium sibiricum and Bidens pilosa)respond to the harsh karst soil environment,by assessing the seed number,seed biomass and offspring seed germination rate.X.sibiricum and B.pilosa were grown under three soil thicknesses and three water availability levels in a full two-way randomized block design.The key results were as follows:(1)The number and biomass of progenies(infructescence and seeds)of X.sibiricum decreased with the decline of soil thickness and/or water availability(P<0.05).The infructescence and seed biomass of B.pilosa increased with the decline of water availability.(2)Seed quantity and seed biomass of X.sibiricum showed no correlation after their parents experienced resource reductions.A significant positive relationship between seed number and seed biomass was observed in B.pilosa(P<0.05).(3)The offspring seed germination rate of X.sibiricum did not change with the decrease of soil thickness under three levels of water treatment.However,the offspring seed germination rate of B.pilosa decreased significantly with the decrease of soil thickness under the control water level(P<0.05).The results show that X.sibiricum tends to improve its competitiveness by ensuring the quantity and quality of offspring in order to adapt to the shallow karst soils and dry karst habitats.In contrast,B.pilosa adapts to the unfavorable karst habitats by a risk-sharing strategy.B.pilosa produces more and bigger seeds to in an attempt to expand its survival range and escape from the unfavorable living environment,but this results in a lower seed number and germination rate of its progeny under the karst soil resource reduction.
