【作者】 葛晋纲；

【导师】 蔡庆生；

【作者基本信息】 南京农业大学 ， 植物学， 2004， 硕士

【摘要】 以两种不同光合类型的草坪草高羊茅（C₃植物，Festuca arunginacea（Shreb．）cv．Houndog）和钝叶草（C₄植物，Stenotaphrum secundatum（Walt）Kuntze cv．Bitter blue）为材料，利用盆钵试验研究了两种草叶片、根颈或匍匐茎、根系的对土壤干旱胁迫的生理响应，以及不同控水处理对两种草茎叶和根系生长特征及抗旱性的影响。 设置灌溉间期3天、6天和9天三种控水处理，分别记作T1、T2和T3，总体上看，高羊茅的根系分布深度、总根长显著高于钝叶草；随着控水时期的延长，高羊茅茎叶干重无显著变化，而钝叶草茎叶干重增加，两种草15cm以下的根长密度增加，高羊茅尤为明显；两种草的总根长、根重均有增加的趋势，高羊茅增加更为明显；在此过程中，高羊茅的冠根比降低，而钝叶草的冠根比升高。在144天间期供水后作断水干旱胁迫处理，高羊茅土壤水势的下降明显快于钝叶草，且一天中的变幅较大，尤其表现在T3处理中；出现表观永久萎蔫症状T1早于T2和T3，高羊茅早于钝叶草；以茎叶生长量、相对含水量与叶绿素含量的变化看，延长供水间期可增强抗旱性。综合上述结果，适当延长控水间期对高羊茅茎叶生长无显著影响，对钝叶草茎叶生长有显著促进作用，有利于两种草根系生长与纵深分布，从而增强草坪草对干旱胁迫的适应性；高羊茅虽然比钝叶草有更深的根系分布，但由于它在断水干旱胁迫下土壤水势的下降快于钝叶草，因而对干旱胁迫的适应能力低于钝叶草。 在断水干旱胁迫条件下，高羊茅的土壤容积含水量、叶片相对含水量比钝叶草下降迅速；在干旱前期高羊茅的根系活力下降快于钝叶草，在干旱后期则慢于钝叶草。在断水的干旱胁迫过程中，两种草叶片与根系的质膜透性和MDA含量不同程度上升，二者呈显著或极显著的正相关；可溶性蛋白质含量、三种抗氧化酶（SOD、POD、CAT）活性均表现出先升后降的变化趋势，根系的这种生理变化早于叶片，相对而言，高羊茅比钝叶草表现得更快、更早。这表明植株失水的快慢所引起的活性氧保护酶变化的迟早可能是盆栽条件下两种草坪草抗旱机制差异的一个重要原因。 在断水干旱胁迫条件下，高羊茅的叶片、根系和根颈以及钝叶草的叶片、根系和匍匐茎中，总可溶性糖、蔗糖、果糖含量都随断水天数的增加而持续上升，其中总可溶性糖在根颈与匍匐茎中积累最多；蔗糖与果糖分别占总可溶性糖的77.6％～93％和6.6％～18.7％；叶片与根系中的淀粉含量变化不显著，根颈或匍匐茎中的淀粉含量下降，且与可溶性糖的积累显著负相关；高羊茅叶片、根系和根颈中的氨其酸与脯氨酸葛晋纲南京农业大学硕士学位论文:高羊茅和钝叶草对干早胁迫的适应性及生理响应含量持续上升，根颈的变幅最大。在干旱胁迫下，钝叶草体内的氨基酸与脯氨酸含量没有出现规则的变化.高羊茅根颈与钝叶草甸旬茎中的r、Ca’‘、Mg卜含量随断水干旱胁迫的持续均出现下降趋势，而叶片与根系中的r、Ca’‘、M广含量则持续上升，其中，叶片与根系中三种离子积累的绝对量大小为K‘>C aZ+>M犷，而除了钝叶草中的caZ净卜，叶片中三种离子积累的绝对量均高于根系。综合上述结果，在干旱胁迫下，总可溶性糖是高羊茅和钝叶草的叶片和根系积累的渗透调节物质，其中蔗糖和果糖既是总可溶性糖的两种最主要的组分，也是干旱胁迫下总可溶性糖积累的主要形式;不同于钝叶草，氨基酸与脯氨酸是高羊茅积累的渗透调节物质，脯氛酸含量的上升可能是氨基酸积累最主要的原因;K+是高羊茅和钝叶草的叶片和根系中进行渗透调节的主要物质，叶片是积累K+主要的器官。 一定时间的断水处理后，植物出现永久表观姜蔫，同期测定高羊茅和钝叶草的光合特性发现，净光合速率、蒸腾速率、气孔导度、水分利用效率和表观量子效率显著低于未断水的对照，而细胞间隙C02浓度、光补偿点则高于未断水的对照，其中钝叶草的净光合速率、水分利用效率、表观量子效率高于高羊茅，而蒸腾速率、光饱和点低于高羊茅，说明钝叶草光合效率与水分利用效率均高于高羊茅，从光合特征及其水分利用效率上看，钝叶草比高羊茅更耐旱。更多还原

【Abstract】 Two different photosynthetic pathway turf-grasses: C3 plant/Houndog’ tall fescue (Festuca arunginacea (Shreb.)) and C4 plant, ’Bitter blue’ St.Augustinegrass (Stenotaphrum secundatum (Walt) Kuntze.) were used to study the physiological responses of progressive drought stress on the leaves, crowns(or stolons), roots and the effects of different irrigating treatments on shoot and root growing characteristic with its relation to drought resistance in two turf-grasses.Three water irrigating treatments (T1, T2, T3 referring to plants irrigated to field capacity every 3, 6, 9 days) were setted, which the data showed: tall fescue had deeper rooting distribution and more total rooting length than Auguestinegrass; Prolonging irrigating interval had no impact on shoot dry matter production of tall fescue but increased that of Augustinegrass, root length density (RLD) of any soil layers below 15cm in two turf-grasses increased, especially appeared in tall fescue; Shoot/root ratio (S/R) of tall fescue reduced, but that of Augustinegrass increased. In subsequent soil drought treatment after 144 days interval irrigation, soil water potential in tall fescue depleted more swiftly, but its diurnal fluctuations showed greater, especially in T3 treatment; Emergence of apparent permanent wilting symptom in Tl were earlier than that in T2 and T3, and that in tall fescue were earlier than that in Auguestinegrass; According to changing data of shoot dry matter production, relative water content and leaf chlorophyll content, prolong irrigating interval could increase drought tolerance. Integrated the above data, the results indicated: moderately prolonging irrigation interval could avail root growth and increase deeper rooting distribution, which would avail turf-grasses to enhance drought resistance. Although rooting distribution of tall fescue was deeper that that of Auguestinegrass, depletion of soil water potential in tall fescue was more swifter that in Augustinegrass, which showed drought resistance was lower than that of Augustinegrass.Under unartificial drought conditions, the soil volumetric water content and leaf relative water content of tall fescue decrease more remarkably than that of St.Augustinegrass; Relative to that in Augustinegrass, depletion of root vitality in tall fescue were swifter in early phase of drought, but were slower in later phase of drought. During drought stress, plasma membrane permeability was keeping increasing in remarked correlations with the malondialdehyde (MDA) content; Soluble protein content and activities of SOD, POD and CAT shows an increase in the early phase of drought and then a decrease with further increase in magnitude of water stress, these physiological responses in roots were more sensitive than those of in leaves, and these changes occurred in tall fescueprior to those of in St.Augustinegrass. The results suggest that water stress alters the equilibrium between free radical production and enzymatic defense reactions in two turf-grasses, and changing time of three protective enzyme activities, caused by plant water-losing speed, may be an important reason of drought resistance mechanism difference between two turf-grasses under potted condition.Under unartificial drought conditions, content of TSC, sucrose and fructose in leaf, root and crown (or stolon) of tall fescue and Augustinegrass showed a sustaining increase with the deepening degree of drought stress. In which TSC accumulated most in crown (or stolon) than in leaf and root; the ratio of sucrose and fructose to TSC was 77.6% ~ 93% and 6.6% ~ 18.7% respectively; Content of starch in leaf and root change unremarkably, but declined steadily in crown (or stolon), which correlated negatively to change of TSC.Content of amino acid and proline increased steadily with the deepening drought stress in leaf, root and crown of tall fescue, especially in crown, while content of these substances did not appear regular change in Augustinegrass. In crown(stolon) of tall fescue(Augustinegrass), content of K+, Ca2+, Mg2+ trended to su更多还原