‘青燕1号’幼苗叶绿素合成和荧光特性对土壤干旱的响应

Response of chlorophyll synthesis and fluorescence characteristics of oat seedlings to soil drought

土壤干旱是限制青海省燕麦(Avena sativa)幼苗生长发育的重要因素之一,为探究燕麦对干旱的响应机理,本研究以青海省主栽燕麦品种‘青燕1号’为试验材料,采用单因素随机区组设计,设4个水分梯度,分别为田间持水量的75%(对照)、60%、45%和30%,探讨幼苗叶绿素及其前体物质和荧光参数变化特点,完善该品种在干旱研究中的不足,为评价燕麦抗旱提供理论基础。结果显示:不同土壤干旱显著影响燕麦幼苗的发育,与对照相比,幼苗株高降低了24.3%~57.4%;叶长宽比降低了44.0%~68.2%,根冠比增加了90.3%~129.0%。干旱导致叶绿素及其前体物质代谢失衡,胁迫增加了叶绿素合成前体δ-氨基乙酰丙酸含量,降低了胆色素原、粪卟啉原Ⅸ、原卟啉Ⅸ、镁原卟啉Ⅸ和原叶绿素酸酯含量,最终造成叶绿素含量下降。叶绿素含量降低引起了燕麦光合系统的光能吸收、利用和分配失衡,土壤干旱下过剩光能主要通过热耗散的形式散失,这可能是燕麦保护光合系统光抑制和光破坏加剧的重要策略。

Soil drought is one of the important factors that restricts the growth and development of oat(Avena sativa)seedlings in the Qinghai Province of China.To clarify the response mechanism of oats to drought,oat variety‘Qingyan No.1’widely cultivated in Qinghai,China,was selected as a test material using a single factor random block design,with four water treatments and field capacity of 75%,60%,45%,and 30%.The purpose of this study was to explore the response characteristics of chlorophyll,precursors,and fluorescence parameters of oat seedlings to drought stress,improve the deficiency of oat variety during drought,and provide a theoretical basis for the evaluation of drought resistance of oats.The results showed that different soil droughts had significant effects on the growth and development of oat seedlings.Compared with the control,the height of seedling decreased by 24.3%~57.4%,the ratio of leaf length to leaf width decreased by 44.0%~68.2%,the ratio of root to shoot increased 90.3%~129.0%.Drought led to metabolic imbalance of chlorophyll and its precursors,mainly characterized by an increase in the content ofδ-aminolevulinic acid and a decrease in the contents of PBG,CopⅨ,ProtoⅨ,Mg-ProtoⅨ,and Pchl,consequently resulting in a decrease in chlorophyll content.The reduced chlorophyll caused the imbalance in light energy absorption,utilization,and distribution in the photosynthetic system of oats.Excess light energy was lost mainly in the form of heat dissipation,which may be an important strategy for oats in protecting the photosynthetic system from photoinhibition and light damage.