滨藜属植物的生长发育规律研究

对努塌滨藜、三角滨藜和四翅滨藜三种滨藜属植物进行了物候期观察、并对其各器官的生物量以及光合速率,蒸腾速率等指标进行观测。其中,对四翅滨藜苗期的生长发育状况进行了重点观测,并和其他两种滨藜属植物及沙棘苗期的生长发育状况进行对比,结果表明,四翅滨藜幼苗较沙棘生长更快,植株更健壮,适合大面积推广。     

干旱胁迫对翅茎白粉藤光合作用及叶绿体超微结构的影响

为探索翅茎白粉藤(Cissus hexangularis)的耐旱性,为矿山修复、石质边坡绿化及屋顶绿化等恶劣环境选择植物提供科学依据,以翅茎白粉藤为试验材料,设置正常浇水、中度干旱胁迫和重度干旱胁迫3个处理,分析不同干旱胁迫对翅茎白粉藤生长性状、光合参数及叶绿体超微结构的影响。结果表明,在中度和重度干旱胁迫下,胁迫后,株高、地上部分鲜重、地下部分鲜重和叶片数均增加,地径、叶长、叶宽和根冠比均降低。随干旱胁迫程度增加,株高增量增加;地上部分鲜重和地下部分鲜重增量均呈先增后降的趋势;地径、叶长、叶宽和叶片数增量均呈降低趋势;根冠比增量呈增加趋势。中度干旱胁迫和重度干旱胁迫下,翅茎白粉藤叶片的净光合速率、气孔导度和胞间CO₂浓度日变化曲线类型均为双峰形,均表现出明显的光合“午休”现象。气孔导度、胞间CO₂浓度和蒸腾速率日均值均降低;净光合速率和水分利用率日均值均呈先升后降的趋势,均在中度干旱胁迫下较高。叶绿体的结构遭到一定程度损坏,受损程度随干旱胁迫程度增加而增加,但是未见死亡植株,表明翅茎白粉藤具有一定的抗旱性。     

干旱胁迫下油茶叶片结构特征的变化

[目的]研究不同程度干旱胁迫对油茶叶片结构的影响,了解其干旱适应机理。[方法]以7年生‘长林4号’油茶为试验材料,设置土壤含水率分别为15%20%(重度干旱胁迫)、20%25%(中度干旱胁迫)、25%30%(轻度干旱胁迫)和自然状况(对照),通过制作石蜡切片、临时切片、光学显微镜观察及测定叶片外部形态特征、叶片下表皮气孔特征、叶肉和叶脉显微结构。[结果]表明:干旱胁迫下,油茶单叶鲜质量、单叶干质量和单叶饱和质量均随着胁迫程度的增加呈下降趋势,叶片厚度、叶片大小显著降低;叶片下表皮气孔面积、气孔周长、气孔开度、气孔器大小均显著减小,气孔密度先减小后增大;随着干旱程度的增强,叶片上表皮、下表皮厚度显著减小,上角质层厚度、下角质层厚度显著增加,栅栏组织厚度、栅海比显著降低,海绵组织厚度变化差异不显著;叶片主脉厚度与主脉突起度随着胁迫程度的加强而显著增加,木质部厚度在中度干旱胁迫下及维管束短径在中度干旱胁迫、重度干旱胁迫下显著低于对照,不同干旱处理对韧皮部厚度的影响差异不显著。[结论]油茶叶片结构的变化均是油茶应对干旱胁迫的适应特征,油茶植株能够根据水分亏缺程度调整叶片结构以维持生存和生长,对干旱胁迫具有较强的适应性。     

干旱对2种沙棘生长和生理特性的影响

以采自四川省红原县的中国沙棘、西藏沙棘幼苗为试材,采用盆栽试验法,对不同土壤水分(对照,即100%田间持水量;中度干旱,即50%田间持水量;极度干旱,即30%田间持水量)条件下中国沙棘和西藏沙棘幼苗生长速率、根超微结构以及不同器官中的碳水化合物含量进行测定。结果表明:在不同水分处理下,中国沙棘生长速率明显高于西藏沙棘;但与对照相比,水分胁迫对中国沙棘的抑制效应更显著。与对照相比,水分胁迫均显著影响了2种沙棘幼苗不同器官中的碳水化合物的积累和分配。极度干旱胁迫下,中国沙棘有更多的根部淀粉、根可溶性总糖、根蔗糖和根果糖含量,表现出较强的根渗透调节能力;而水分胁迫对西藏沙棘地上茎和叶碳水化合物的影响比地下部分更显著。中度水分胁迫时,2种沙棘的根系超微结构未有明显变化;而极度水分胁迫时,2种沙棘均显示根细胞超微结构的损伤。表明中度水分胁迫下,中国沙棘和西藏沙棘表现出较好的适应能力,而极度水分胁迫不同程度地影响了2种沙棘幼苗的生长和碳代谢能力。     

干旱胁迫对降香黄檀幼苗生理特性及根系形态特征的影响

采用盆栽控制土壤水分法,研究了1年生降香黄檀幼苗在不同干旱梯度胁迫条件下相对电导率、游离脯氨酸含量、光合特性等生理指标以及根系形态参数的变化.结果表明:随着干旱胁迫的加强,降香黄檀幼苗叶片电导率和脯氨酸含量变化整体呈上升的趋势;净光合速率Pn、蒸腾速率Tr、气孔导度Gs均下降,胞间CO2浓度Ci先降后升;与正常供水(W1)相比,在轻度干旱胁迫(W2)条件下,降香黄檀叶片Pn的降低主要是由气孔限制引起的,而在中度干旱胁迫(W3)和重度干旱胁迫(W4)条件下则主要由非气孔因素引起的.在重度干旱胁迫下,降香黄檀总根长、总根尖数和平均根系直径均显著降低,说明降香黄檀幼苗的耐旱能力有限.     

沙棘无性系对干旱胁迫的响应研究

为揭示沙棘抗旱特性,在整个生长季对5个无性系进行干旱胁迫处理(正常水分、中度干旱、重度干旱),观测不同处理下叶性状、光合特性及酶活性等,确定其响应机制.结果表明,沙棘无性系的净光合速率、蒸腾速率、气孔导度都以正常水分条件下最高,重度干旱条件下最低.在重度干旱胁迫时,"杂雌优2号"、"杂雌优10号"、"杂雌优54号"的长...     

石漠化地区3个树种幼苗在水分胁迫下的光合特性与抗旱性关系

采用盆栽控水方法,研究了翅莢木、滇楸和银荆树3树种当年生实生苗的光合特性与抗旱性的关系.结果表明:随着干旱胁迫强度的增加和时间的延长,3树种的净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)均呈下降趋势,而胞间CO2浓度则呈上升的趋势;净光合速率日变化曲线逐渐从典型的单峰型转变成双峰型,出现"光合午休"现象.在轻度胁迫和中度胁迫下,净光合速率的降低是由气孔因素和非气孔因素共同引起的:而重度胁迫下,净光合速率的降低主要是非气孔因素引起的.干旱复水后,3个树种的净光合速率均有明显的恢复.利用隶属函数与反隶属函数法对3个树种的抗旱能力进行综合评价,其抗旱能力为:银荆树＞翅莢木＞滇楸.     

干旱复水对胡杨(Populus euphratica)幼苗生理特性的影响

以2a生胡杨实生苗为材料,采用盆栽称重法研究轻度(持续干旱6d)、中度(持续干旱12d)和重度(持续干旱18d)干旱及旱后复水过程中幼苗光合气体交换、叶绿素荧光参数及光合色素、可溶性糖、丙二醛(MDA)等含量的变化,探讨不同程度干旱及复水过程中胡杨幼苗生理生化响应与旱后恢复能力的关系。结果表明:(1)持续干旱,幼苗叶片光合速率(Pn)、有效光化学量子效率(Fv/Fm)、PSII反应中心光捕获效率(Fv'/Fm')、实际光化学量子效率(ΦPSII)及光合色素含量均随干旱时间的延长和土壤含水量的减小逐渐下降;轻度和中度胁迫幼苗Pn分别下降了25%和60%,但Fv/Fm、Fv'/Fm'、ΦPSII与对照无显著差异(p0.05),较短期的缺水条件下幼苗光合系统稳定;重度胁迫,幼苗Pn接近零,光合几乎完全受抑,Fv/Fm下降17%,长期缺水致使幼苗光合器官受损。(2)中度和重度干旱胁迫,幼苗叶片丙二醛含量显著,细胞膜遭到破坏;幼苗可溶性糖、Chl a/b、非光化学猝灭系数(NPQ)增大,其通过渗透调节提高抗旱性,减少光捕获及热耗散以避免过剩光对光合机构造成更大损伤;(3)轻度和中度胁迫后复水,幼苗光合、荧光参数均在短期内快速恢复,重度胁迫也在复水8d完全恢复,反映了幼苗较强的旱后修复能力;轻度胁迫幼苗叶片Pn和叶绿素含量均显著高于对照,表现出补偿效应,表明适度干旱诱导了幼苗的抗旱适应性。研究发现,干旱胁迫对胡杨幼苗光合生理具有显著抑制作用,但胡杨通过一些列光保护、光适应机制以及渗透调节等使其在干旱胁迫环境下生存,并能够在复水后完全恢复。     

不同沙棘品种抗旱性的比较

沙棘抗旱性是多因素作用的结果,如果只利用单因素/单项指标评价其抗逆性,则具有一定的片面性。本研究对干旱胁迫下4个沙棘品种的多项生理生化指标的变化进行比较分析,并通过主成分分析和综合评价发现:乡土中国沙棘(河北丰宁种源)品种的抗旱性最强,引进大果沙棘―乌兰格木品种的抗旱性最差,引进的4个沙棘品种抗旱能力强弱的排序为:丰宁(0.619)> 楚伊(0.445)> 向阳(0.390)> 乌兰格木(0.274)。净光合速率、蒸腾速率、气孔导度、叶水势、谷胱甘肽还原酶和脱落酸的含量可作为沙棘抗旱性的判定指标。随着干旱胁迫的加剧,与对照相比,4个引沙棘品种的净光合速率、蒸腾速率、气孔导度和叶水势均下降,而超氧化物歧化酶活性、细胞膜透性、谷胱甘肽还原酶和四大激素均上升,这说明干旱逆境胁迫影响了沙棘正常的生长发育过程,同时通过内在的生理生化指标的改变来增加其自身对逆境胁迫的抵抗能力。这些将为沙棘抗旱树种的筛选和进一步的杂交育种提供依据。     

臭氧与干旱交叉胁迫对3树种幼苗光合生理的影响

将尖叶杜英(Elaeocarpus apiculatus)、米老排(Mytilaria laosensis)和藜蒴(Castanopsis fissa)幼苗置于开顶气室进行人工臭氧熏气和干旱处理,测定其0,15,30 d时的净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)、蒸腾速率(Tr),并计算气孔限制值(Ls)。结果显示:(1)臭氧胁迫、干旱胁迫及臭氧和干旱交叉胁迫的影响下,3种幼苗的Pn、Gs和Tr随处理时间的延长均呈下降趋势,Ci上升或下降后上升,Ls下降或上升后下降;(2)臭氧胁迫期间,尖叶杜英的Pn下降由非气孔限制引起,而米老排和藜蒴的Pn下降由气孔限制转为非气孔限制所致;干旱胁迫期间,尖叶杜英和米老排的Pn下降由气孔限制转为非气孔限制所致,而藜蒴的Pn下降由非气孔限制引起;在臭氧与干旱交叉胁迫下,3种幼苗的Pn下降均由非气孔限制所致;(3)主成分分析表明,幼苗抗干旱胁迫及臭氧与干旱交叉胁迫的能力为米老排尖叶杜英藜蒴,幼苗抗臭氧胁迫的能力为米老排藜蒴尖叶杜英。     

水蚀风蚀交错区典型人工林土壤水分亏缺特征

为充分了解水蚀风蚀交错区典型林地土壤水分差异性及其生态水文效应,选择陕西省延安市吴起县水蚀风蚀交错区长城镇退耕还林后形成的典型人工林(小叶杨、山杏、山桃、柠条、河北杨和沙棘林)为研究对象,采用烘干法测定土壤含水量,分析0~300 cm土层土壤水分季节变化特征、贮水量特征和土壤贮水亏缺程度。结果表明:在0~300 cm土层,6种林地土壤水分具有明显的垂直变异特征,即随着土层深度的增加,土壤含水量先升高后降低;6种林地各土层的土壤含水量均具有明显的季节变化特征,且变异系数在表土层较大,随着深度的增加而减小;6种林地土壤水分活跃层存在一定的差异性;其中,沙棘林土壤水分活跃层最深(0~80 cm),其它林地相对较浅(20~40 cm);在0~100 cm土层,各林地土壤贮水量垂直变化趋势差异较大,且小叶杨、河北杨与沙棘林差异显著(P<0.05),沙棘各季节土壤贮水量随着土层深度的增加呈现先增大后减小的趋势。不同植被类型土壤贮水亏缺度存在差异,土壤水分亏缺度在季节上表现为秋季>春季>夏季。     

Effects of soil drought on photosynthetic traits and antioxidant enzyme activities in Hippophae rhamnoides seedlings

Water deficit is one of the major limiting factors in vegetation recovery and reconstruction in the semi-arid area of loess hilly regions. Leaf photosynthesis in Hippophae rhamnoides Linn., a common tree grown in this region, decreases under water stress, but the mechanism responsible is not clear. The objective of this study was to investigate the effects of drought stress on photosynthesis and the relationship between photosynthetic variables and soil water contents to help us better understand the photophysiological characteristics of H. rhamnoides under water stress and guide cultivation in the loess hilly region. Here,gas exchange, chlorophyll fluorescence and antioxidant enzyme activity in leaves of 3-year-old saplings of H.rhamnoides grown in pots were tested under eight soil water conditions. When soil water content(RWC) was between 38.9 and 70.5 %, stomatal limitation was responsible for the reduced net photosynthetic rate(PN).When RWC was lower than 38.9 %, nonstomatal limitation was the main factor restricting PN. Moderate water stress improved the water use efficiency(WUE) of the leaf.Water stress significantly influenced fluorescence variables and the antioxidant enzyme system. When RWC was between 38.9 and 70.5 %, nonphotochemical quenching(NPQ) increased and then decreased, indicating that thermal energy dissipation was a significant photoprotection mechanism. Antioxidant enzymes were activated when RWC ranged from 48.3 to 70.5 %; under severe water stress(RWC \ 38.9 %), the antioxidant enzyme system was damaged, the activity of the antioxidant enzymes declined, and membranes were damaged. In the semiarid loess hilly region, RWC between 58.6 and 70.5 % was the economic water threshold value that maintained higher WUE and PN, and the maximum soil water deficit level that could sustain H. rhamnoides was RWC of 38.9 %.     

三峡库区杉木马尾松混交林和马尾松纯林的土壤含水量空间变异性

土壤水分含量是对地表生态过程有着重要影响的生态因子,在三峡库区生态环境保护中具有重要作用。选取三峡库区典型植被类型杉木、马尾松混交林(A)和马尾松纯林(B),通过网格(3.00 m×3.00 m)取样,地统计学方法研究群落(30.00 m×30.00 m)0.00 - 20.00 cm土壤水分的空间特征。结果表明:(1)两种典型植物群落土壤含水量空间变异性不同,样地A和样地B土壤含水量的变异系数分别表现出弱和中等强度的变异性;(2)两种典型植物群落土壤水分具有良好的半方差结构,半方差函数曲线可以用球状模型进行拟合。土壤水分的空间相关范围存在明显的差异,有效变程分别为51.00 m和12.37 m;土壤水分分布格局呈明显的斑块状分布;(3)在本研究区域内,植被、地形和地貌等是影响土壤含水量空间异质性的主要因素。     

三种灌木耐旱性研究

用盆栽法设置三种土壤相对含水量，研究紫穗槐，沙棘，柠条的耐旱能力。测定了生长指标，计算出耐旱生产力；研究了水分胁迫对蒸腾日进程和叶保水力的影响；用压力室和ＰＶ技术测定并计算了水分胁迫对苗木渗透调节能力和水分状况等影响。综合上述三类指标，得出柠条的耐旱性最强，其耐旱生产力，蒸腾，保水力和渗透调节能力最高。沙棘和紫穗槐的耐旱性接近，沙棘的蒸腾和保水力的调节能力大于紫穗槐，但渗透调节能力却低于紫穗槐，它     

Morphological and water-stress characteristics of three Douglas-fir stocktypes in relation to seedling performance under different soil moisture conditions

This one-time greenhouse study examined the phenology, morphology, frost hardiness and response to moisture stress of three Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stocktypes from the same seed lot. The types were mini-plug^TM transplants (MPT), 1+1 bareroot transplants (1+1), and 2+0 bareroot seedlings (2+0). In late summer and fall before lifting, 2+0 seedling set bud before 1+1 seedlings, 1+1 seedlings before MPT seedlings. The 2+0 seedlings appeared slowest to acquire frost hardiness in fall and seemed to deharden most rapidly in spring. Although the 2+0 seedlings were taller than the MPT stocktype, MPT and 2+0 seedlings were relatively similar in other morphological respects, but 1+1 seedlings were much larger. All stocktypes were potted on January 20, 1989, placed in a greenhouse, and subjected to 39%, 18%, 16%, or 6% soil water content (% dry weight) until the end of the experiment in mid-July 1990. The largest decrease in pre-dawn xylem water potential occurred with 16% and 6% soil water content; pre-dawn xylem water potential averaged over the three stocktypes generally declined 219% from low to high soil moisture stress. The 1+1 seedlings used more water than the other two stocktypes, and at maximum soil moisture stress, plant moisture stress increased in the order: MPT <2+0<1+1. During the 6-month greenhouse experiment, the larger 1+1 stocktype showed the most absolute growth, but the smaller stocktypes grew more on a relative scale. Growth of the stocktypes appeared to be related to differences in morphology and water-use patterns as the seedlings competed for available water within each pot. The results show that MPT seedlings, a new stocktype, performed as well as the more traditionally used 2+0 and 1+1 seedlings and that stocktype selection is important in reforestation efforts.     

青海湟水河流域不同退耕还林模式水文效应

基于野外采样、定点观测和室内实验,研究青海湟水河流域不同退耕还林模式水文效应,结果表明：不同林分类型枯落物有效持水性大小顺序为云杉桦树混交〉桦树〉云杉〉沙棘,其林下土壤持水性大小顺序为云杉桦树混交〉沙棘〉桦树〉云杉〉农田;森林土壤是森林生态系统水文效应的主体,枯落物和土壤总持水性大小顺序为云杉桦树混交〉沙棘〉桦树〉云杉〉农田。不同林分类型枯落物持水量决定于枯落物蓄积量和自然含水率,其林下土壤持水量决定于土壤非毛细管孔隙度。     

土壤温度和水分变化对川西云杉幼苗氮和磷含量的影响

【目的】研究不同梯度的土壤温度和水分对川西云杉幼苗生长性状和各器官氮和磷含量的影响,以期为全球气候变暖背景下解释川西云杉树线形成的原因提供参考和数据积累。【方法】以5年生川西云杉幼苗为试验材料,采用人工气候室结合嵌套设计,设置5个土壤温度梯度(2、7、12、17、22℃)和3个土壤水分梯度(干旱处理、正常水分含量处理、饱和水分含量处理)。每处理9株幼苗,共135株幼苗。实验处理4个月后,测定并比较分析不同梯度的土壤温度和水分对幼苗的生长性状、各器官干物质含量、各器官全氮、全磷浓度和含量以及土壤全氮和全磷浓度的影响。【结果】土壤温度处理对幼苗基径和株高生长量均无显著影响,而土壤水分处理对幼苗株高生长量有显著影响;在2℃和7℃土壤温度干旱处理下显著降低了幼苗的株高生长量,但随着土壤温度的升高其影响效应不显著。土壤温度处理对土壤氮和磷浓度无显著影响,而干旱处理显著升高了土壤氮和磷浓度。川西云杉幼苗各器官的氮和磷浓度以及当年生叶氮含量随土壤温度降低显著降低;干旱和饱和水分处理显著降低了当年生叶和当年生枝的氮浓度,饱和水分处理显著降低了当年生叶的磷浓度,干旱处理显著降低了当年生枝、茎和根的磷浓度,干旱和饱和水分处理显著降低了当年生叶和根的氮和磷含量,且随着土壤温度升高影响效应更显著。【结论】在短期内,土壤低温对川西云杉幼苗的生长性状没有明显的制约作用,但对川西云杉幼苗各器官的氮和磷浓度及含量影响显著,尤其是当年生叶和根的氮和磷浓度及含量。在川西地区,低温、干旱等极端气候胁迫导致的云杉幼苗氮、磷含量的不足很可能是限制川西云杉垂直分布的重要因素。此外,土壤温度和水分处理存在显著的交互作用,随着土壤温度的降低,水分胁迫对幼苗各器官氮和磷含量的影响由显著变得不再显著,说明随着海拔升高,与水分因子相比,土壤低温成为造成云杉各器官营养元素亏缺的主导因子。     

成年马尾松针叶水势和形态对隔离降雨的响应

通过在福建省长汀县红壤严重侵蚀区以持续100%隔离降雨模拟水分亏缺环境,研究土壤含水量变化对先锋造林树种马尾松针叶水势、针叶形态的影响,评价马尾松在水分胁迫下的生态适应性及生理调节机制。结果表明:(1)研究期内,处理组20 cm和80 cm土层土壤含水量持续下降并显著低于对照组(P<0.05),差异达10.93%和12.17%,表明土壤环境已出现水分亏缺;(2)处理组针叶水势(Ψd)持续下降,平均值为-3.73 MPa,显著低于对照组-2.80 MPa(P<0.05),证明处理组土壤含水量下降已对马尾松针叶水势产生了显著的影响,且通过拟合土壤含水量与针叶水势关系得出先锋造林树种马尾松具有较强的抗旱能力;(3)马尾松针叶形态相关指标分析表明,隔离降雨第2 a内对照组与处理组间叶长、叶宽、叶面积的差值均明显大于第1 a内,说明生长减缓是该地区马尾松应对土壤水分亏缺的重要途径。     

Seasonal variations in soil water in two woodland savannas of central Brazil with different fire history

Changes in soil water content were determined in two cerrado (sensu stricto) areas with contrasting fire history and woody vegetation density. The study was undertaken near Brasília, Brazil, from 1999 to 2001. Soil water content was measured with a neutron probe in three access tubes per site to a depth of 4.7 m. One site has been protected from fire for more than 30 years and, as a consequence, has a high density of woody plants. The other site had been frequently burned, and has a high herbaceous vegetation density and less woody vegetation. Soil water uptake patterns were strongly seasonal, and despite similarities in hydrological processes, the protected area systematically used more water than the burned area. Three temporarily contiguous patterns of water absorption were differentiated, characterized by variation in the soil depth from which water was extracted. In the early dry season, vegetation used water from throughout the soil profile but with a slight preference for water in the upper soil layers. Toward the peak of the dry season, vegetation had used most or all available water from the surface to a depth of 1.7 m, but continued to extract water from greater depths. Following the first rains, all water used was from the recently wetted upper soil layers only. Evaporation rates were a linear function of soil water availability, indicating a strong coupling of atmospheric water demand and the physiological response of the vegetation.     

Use of water stress integral to evaluate relationships between soil moisture,plant water stress and stand productivity in young Douglas-fir trees

Water stress integral (WSI) is a method of assessing cumulative plant water stress over a chosen period of time. While the technique has been used in other tree species, it has not been applied for reforestation projects. In this study we used the WSI approach for newly planted Douglas-fir in the Pacific Northwest (USA), where the Mediterranean climate, plant community development, and competition for water all play key roles in the success of establishment efforts. In this study, previously reported seedling growth, xylem water potential, and soil moisture data were utilized to provide direct correlations between Douglas-fir productivity, soil water availability and WSI. For each growing season, a strong relationship between WSI and volume growth as well as a strong linear relationship between WSI and soil moisture measured during mid-August was found. On average, for each reduction of 0.01 cm³ cm^?3 in soil moisture measured during mid-August, Douglas-fir seedling volume growth decreased by 5.6 and 7.7% in the first and second growing seasons, respectively. Preserving soil moisture until early-August through the judicial application of vegetation management regimes was critical for maximizing stand productivity. Based on these results, a single evaluation of soil volumetric water content during early-August can be used as a predictor of stand productivity during the initial two seasons of forest establishment.