断根对冬小麦荧光特性和产量的影响

用荧光淬灭分析技术研究了断根对冬小麦荧光特性的影响以及不同水分条件下断根对产量的影响.结果表明,在不同生育期中小麦断根与未断根处理相比其最大量子产量(Fv/Fo)和PSⅡ潜在活性(Fv/Fm)无显著差异.通过对不同生育期荧光特性研究表明,断根初期小麦电子传递速率和有效光量子产量降低,而PSⅡ光合电子传递活性增加,孕穗期随着更多的能量向地上部的运转,此时根系补偿作用使ETR、ΦPSⅡ和qP增加,而且断根并显著降低光系统Ⅱ光化学效率.混播处理ΦPSⅡ和ETR值高于单播处理,认为断根降低了小麦的竞争能力,使总体光合活性增强,促进了能量向地上部运转,与混播处理产量增加相一致.小麦单播湿润处理下,断根降低了小麦穗重和地上部生物量,且籽粒产量降低了19.2%.在干旱处理下,断根降低了根冠比,提高了小麦穗重和籽粒产量.     

黄土旱塬冬小麦返青期断根对根冠比、水分利用及产量的影响

采用适当的农艺措施来影响根系生长以提高作物水分利用效率是节水农业研究的一项重要内容。通过田间试验研究了旱作冬小麦‘长武135’(Triticum aestivum cv. Changwu135)返青期切断部分侧生根对根冠比、水分利用效率及产量的影响。与不断根处理相比,冬小麦切断部分侧根后,极显著地减少了表层的根量,花期时断根和不断根小麦在0~20 cm土层根量分别249.70和307.52 g·m^-2,100 cm以上总根量分别为305.53和368.73 g·m^-2。断根比不断根处理根呼吸速率下降了25.57%。断根也抑制了小麦的群体数量,断根和不断根处理单位面积的穗数分别为590.33和646.33 m^-2,但断根显著增加了千粒重,断根和不断根分别为45.99和41.47 g,收获指数也有一定提高。断根对籽粒产量没有显著影响,但断根后土壤含水量显著增加,水分消耗减少。以生物量计算的水分利用效率和以产量计算的水分利用效率分别提高了32.52%和29.98%。因此,在旱地农业中,通过返青期人工断根措施削减根系降低根系对同化产物的消耗和减少耗水量来达到提高冬小麦水分利用效率的方法,是可行的。但今后还需对断根措施作进一步研究,以期实现产量和水分利用效率的同步提高。     

花后干旱或渍水逆境下氮素对小麦籽粒产量和品质的影响

 池栽试验条件下,设置渍水、干旱和对照3个水分处理,每个水分处理下设置两个施氮水平 ,研究了花后渍水或干旱逆境下氮素营养对两个不同类型小麦（Triticum aestivum） 品种籽粒产量和品质性状的影响。结果表明,与对照相比,花后渍水或干旱处理显著降低了小麦的千粒重、穗粒数和籽粒产量。在适宜水分和干旱条件下,增施氮肥增加了小麦籽粒产量,而在渍水条件下,增施氮肥降低了产量。干旱处理提高了蛋白质含量,干、湿面 筋含量,沉降值和降落值;而渍水处理则降低了小麦籽粒蛋白质含量和干、湿面筋含量。同 一水分处理下,增施氮肥提高了蛋白质含量,谷蛋白/醇溶蛋白比,支链淀粉含量和支/直链淀粉比。在小麦籽粒主要品质性状上存在显著的水氮互作效应,且水分、氮肥及水氮互作效 应对小麦籽粒产量和品质的影响因品种的不同而异。     

土壤水分对返青期断根冬小麦补偿效应的影响

通过盆栽试验研究了不同土壤水分条件下返青期断根冬小麦的补偿效应.结果表明,断根小麦的早期生长受到抑制,叶面积在返青 拔节期间显著下降,到开花期能恢复至对照水平.高水分条件下断根小麦拔节期的叶绿素荧光参数包括表观光合电子传递速率、实际光化量子产量、光化学淬灭系数、非光化学淬灭值均显著大于对照,开花后单茎干物质积累为0.81 g,显著大于对照（0.56 g）,花后干物质积累系数比对照提高了38.79%,断根小麦根量虽有所下降但差异不显著;低水分条件下断根小麦的叶绿素荧光参数和花后干物质积累与对照之间没有显著差异,但断根小麦的根系生物量（7.83 g·pot^-1）显著小于对照（9.77 g·pot^-1）.土壤水分对断根小麦的地上生物量和籽粒产量的补偿效应没有显著影响.断根处理的冬小麦在两种土壤水分条件下均显著降低了耗水量,在整个生育期,高水分条件下冬小麦断根处理可节水2 000 ml左右,水分利用效率为1.97 g·kg ^-1,显著大于对照的1.70 g·kg ^-1;低水分条件下也可节水1 500 ml左右,水分利用效率虽有所提高,但未达到显著性差异.     

带距对小麦蛋白质产量的影响及边际效应分析

以冬小麦品种豫麦 34为材料 ,在不同带距条件下对小麦籽粒产量、蛋白质含量和蛋白质产量以及三者相互关系进行了研究。结果表明 :带距对蛋白质产量和籽粒产量有显著的影响 ,对籽粒蛋白质含量影响不明显 ;蛋白质产量与籽粒产量呈现极显著正相关 ,与籽粒蛋白质含量关系不密切 ;蛋白质产量与籽粒产量之间存在着直线回归关系 ,二者的模拟方程为 :Y =10 6 80 9+0 10 7X(kg·hm-2 ) ;2 0m带距条件下小麦籽粒产量最高 ;2 4米带距条件下 ,小麦边行优势总值最大 ,与其它作物套作 ,效益较好。     

土壤水分对两个冬小麦品种产量和竞争能力的影响

研究了黄土塬区两个旱作冬小麦品种(长武135和平凉40,前者是后者的换代品种)在不同土壤水分条件下竞争能力和产量形成的关系。研究设2种土壤水分条件(土壤含水量为田间最大持水量的75%～80%和40%～45%),采用生态替代法设计了同一播种密度的6个播种比例组合的盆栽试验。低水分单播条件下,长武135具有较高的产量(长武135为27.59g/pot,平凉40为24.91g/pot),而混播条件下平凉40在产量和相对产量上较长武135品种具有明显的竞争优势。高水分条件下,平凉40产量随播种比例的减小下降较快(长武135产量曲线斜率35.468,平凉40为36.237)。平凉40低水分单播时花后干物质积累量较少(长武135为0.67g/pot,平凉40为0.55g/pot),而混播时较多(长武135各比例均值0.58g/pot,平凉40为0.71g/pot),导致了平凉40品种单播时产量较低和混播时产量较高。平凉40地下生物量显著大于长武135(高水分条件下,长武135为10.03g/pot、平凉40为11.51g/pot;低水分条件下二者分别为8.41g/pot和10.69g/pot),且耗水量大(高水分条件下平凉40多耗水2.72kg/pot,低水分条件下多耗0.98kg/pot),而耗水量/地下生物量的比值平凉40低于长武135,从而平凉40品种单位根量消耗的水分低于长武135。总之,在两个生长属性接近的冬小麦品种中,老品种以较大的根系生物量赢得了较高的竞争能力,消耗了较多的水分,而新品种虽然根系生物量较低,耗水量较少,但籽粒产量却较高。亦即,小麦新品种籽粒产量的提高是与根系的减少和对水资源竞争能力的下降相伴随的。     

施氮水平对2种穗型冬小麦品种产量及氮素吸收利用的影响

在大田高产栽培条件下,以大穗型小麦品种‘兰考矮早八’和多穗型品种‘豫麦49-198’为材料,研究了4个施氮水平下2种穗型冬小麦品种的籽粒产量、氮素吸收和氮肥利用效率。结果显示:随着施氮水平的提高,2种穗型小麦植株地上部生物量(返青期、拔节期除外)、籽粒产量和籽粒蛋白质产量均呈先增加后降低的趋势并都显著高于对照(不施氮),且均以180 kg.hm-2施氮处理最高,而2品种小麦各生育期植株氮素积累量和成熟期籽粒蛋白质含量却逐渐增加,且大都显著高于对照;2品种小麦的氮肥利用率、土壤氮贡献率以及氮收获指数均表现出180 kg.hm-2>90 kg.hm-2>360 kg.hm-2的趋势,且不同氮肥处理间均存在极显著差异(P<0.01)。研究表明,2种穗型冬小麦品种在试验条件下施用纯氮180 kg.hm-2可获得较高籽粒产量、蛋白质产量和氮收获指数。     

小麦品种抗旱性评价指标研究

以抗旱性不同的冬小麦品种为材料,在正常降雨年型的干旱处理（DT）和正常灌溉（CK）条件下,对于不同类型抗旱品种的产量形成能力、抗旱性评价指标以及相关抗旱生理参数进行了较全面的研究。结果表明,可采用抗旱指数（DRI）和产量降低指数（YDI）作为评价小麦品种抗旱性强弱的指标。供试品种成熟期单株干物重具有较大的差异,表现为随着品种抗旱性的增强而不断增加,表明干旱条件下单株干物重的大小与小麦品种的抗旱性具有密切联系。研究发现,单位面积穗数与产量降低指数的相关达到极显著水平,表明在干旱条件下单位面积具有较多的穗数形成能力,对于干旱条件下小麦获得相对较高的产量具有重要作用。旗叶全展、中期和生长后期的净光合速率（Pn）和脯氨酸含量均与抗旱指数和产量降低指数、叶绿素含量与产量降低指数分别呈显著或极显著相关,表明可用植株旗叶的Pn、叶绿素含量和脯氨酸含量作为评价小麦品种抗旱性强弱的参考生理指标。     

花后土壤水分状况对小麦籽粒淀粉和蛋白质积累关键调控酶活性的影响

在温室盆栽条件下,以2个不同蛋白质含量的冬小麦(Triticum aestivum L．)品种皖麦38和扬麦9为材料,研究了花后第4天开始的土壤干旱(SRWC=45％～50％)和渍水对籽粒蛋白质和淀粉积累关键调控酶活性的影响。小麦叶片和籽粒的测定结果均表明,小麦源库器官中籽粒蛋白质和淀粉积累的关键调控酶活性变化趋势在2个品种间基本一致。与对照(SRWC=75％～80％)相比,干旱和渍水均明显降低了花后旗叶中蔗糖含量和磷酸蔗糖合成酶(SPS)活性,而氨基酸含量和谷氨酰胺合成酶(GS)活性略有下降。干旱和渍水均降低了籽粒库蔗糖合成酶(SS)和结合态淀粉合成酶(GBSS)活性,可溶性淀粉合成酶(SSS)活性降低尤甚。其中干旱处理下SS的下降比渍水更为明显。与对照相比,渍水明显降低了籽粒谷丙转氨酶(GPT)和GS活性,而干旱的影响较小。相关性分析结果表明籽粒淀粉产量和含量与SPS,SSS和GBSS活性的关系比与SS活性的关系更为密切,籽粒蛋白质产量和含量与叶中GS和籽粒中GPT活性的关系比与籽粒中GS关系活性更为密切。这些结果表明小麦源库器官中调控籽粒蛋白质和淀粉积累的关键酶活性变化是花后不同水分状况影响籽粒淀粉和蛋白质特性的重要因素。     

水肥空间组合对冬小麦光合特性及产量的影响

以肥熟土垫旱耕人为土为供试土壤,用分层土柱试验法研究了不同土层水分、氮、磷空间组合对冬小麦不同生育时期光合特性及籽粒产量的影响.结果表明:与0～90cm土层整体湿润相比,上干下湿(0～30cm土层干旱胁迫,30～90cm土层湿润)水分处理显著降低了小麦叶片叶绿素相对含量(SPAD)、净光合速率(Pn)和籽粒产量.2种水分条件下,氮磷配施处理对叶片SPAD、Pn和小麦籽粒产量的影响最为显著,其次是施磷处理,而施氮处理影响不显著.不同土层施氮在2种水分条件下各指标的变化趋势相同,均表现为0～90cm土层施氮小麦叶片SPAD、Pn及籽粒产量显著高于0～30、30～60和60～90cm土层施氮.不同土层施磷在2种水分条件下各指标的变化趋势也相同,表现为0～90cm土层施磷小麦叶片SPAD、Pn和籽粒产量与0～30cm土层施磷间差异不显著.不同土层氮磷配施在2种水分处理下表现不同:整体湿润条件下0～90cm土层施肥处理的小麦叶片SPAD、Pn及籽粒产量最高,与0～30cm土层差异不显著,但二者均显著高于30～60和60～90cm土层处理;上干下湿条件下各土层施肥处理间小麦叶片SPAD差异不显著,0～90cm土层施肥处理小麦叶片Pn和籽粒产量显著高于30～60cm土层施肥处理,30～60cm土层施肥处理显著高于60～90cm土层施肥处理和不施肥处理.表明在2种土壤水分条件下,氮磷配施时仍应施入0～30cm土层.     

Biomass Accumulation and Main Stem Elongation of Durum Wheat Grown under Mediterranean Conditions

Detecting and exploiting genetic variation in biomass accumulationis of great importance for increasing wheat yield when the harvestindex is close to its upper limit. This study was undertakento analyse the pattern of biomass accumulation and main stemelongation in 25 durum wheat (Triticum turgidum L. ‘Durum’)genotypes. Field experiments were conducted over 2 years intwo environments contrasting in the amount of available water,in northeastern Spain. Plants were sampled at the main stagesof Zadoks' scale, and dry weight per plant, crop dry weight(CDW) and main stem length were measured at each stage. Measurementsfor growth traits and thermal time from sowing fitted betterto an asymmetric logistic peak curve than to the Richards logisticmodel. Four biological variables were computed from the curve.Differences among curves describing changes in biomass werefound to be greater between irrigated and rainfed sites thanbetween years. Drought stress had less effect on main stem elongationthan on biomass accumulation. Average dry weight per plant andCDW were reduced by drought by 42 and 38%, respectively, duemainly to similar reductions in the mean rate of growth of thetwo variables. In contrast, cycle length from sowing to themaximum values of dry weight per plant and CDW was only slightlymodified by drought. Copyright 2001 Annals of Botany Company Triticum turgidum L. ‘Durum’, durum wheat, biomass, crop dry weight, stem length, rate of growth, modelling, growth analysis, logistic peak curve     

Drought tolerance and proteomics studies of transgenic wheat containing the maize C<Subscript>4</Subscript> phosphoenolpyruvate carboxylase (<Emphasis Type="Italic">PEPC</Emphasis>) gene

Enhancing drought tolerance of crops has been a great challenge in crop improvement. Here, we report the maize phosphoenolpyruvate carboxylase (PEPC) gene was able to confer drought tolerance and increase grain yield in transgenic wheat (Triticum aestivum L.) plants. The improved of drought tolerance was associated with higher levels of proline, soluble sugar, soluble protein, and higher water use efficiency. The transgenic wheat plants had also a more extensive root system as well as increased photosynthetic capacity during stress treatments. The increased grain yield of the transgenic wheat was contributed by improved biomass, larger spike and grain numbers, and heavier 1000-grain weight under drought-stress conditions. Under non-stressed conditions, there were no significant increases in these of the measured traits except for photosynthetic rate when compared with parental wheat. Proteomic research showed that the expression levels of some proteins, including chlorophyll A-B binding protein and pyruvate, phosphate dikinase, which are related to photosynthesis, PAP fibrillin, which is involved in cytoskeleton synthesis, S-adenosylmethionine synthetase, which catalyzes methionine synthesis, were induced in the transgenic wheat under drought stress. Additionally, the expression of glutamine synthetase, which is involved in ammonia assimilation, was induced by drought stress in the wheat. Our study shows that PEPC can improve both stress tolerance and grain yield in wheat, demonstrating the efficacy of PEPC in crop improvement.     

不同倍性冬小麦种内竞争能力的比较研究

通过3个不同倍性冬小麦材料(两倍体栽培一粒、四倍体栽培两粒、六倍体现代品种长武134),在不同水分条件下进行密度实验,研究了不同材料的株高、生物量累积和分蘖动态的变化,以及产量对密度变化的反应。结果表明随着群体的增大,不同倍性材料个体间竞争明显加剧,相互抑制作用增强,种群内部个体大小等级差异增大;在不同群体下各倍性材料的个体生长存在差异,表现为四倍体栽培两粒竞争能力两倍体栽培一粒六倍体现代品种长武134,且长武134受种群大小影响最为显著,但长武134产量累积的投入比例最高,产量最高,低竞争能力的个体更适合生产上的需求,是群体高产的基础。研究结果为旱地小麦的高产栽培和育种提供了理论基础。     

Exotic tree seedlings are much more competitive than natives but show underyielding when growing together

Aims Invasive species continue to be a worldwide threat to ecosystems mainly as a cause for biodiversity loss. Forest ecosystems, for example, are subject to a change in species composition due to the invasion of exotic species. Specifying the attributes that cause the strong competitiveness of several exotic species may improve the ability to understand and effectively manage plant invasions in the future. In this study the following hypotheses were tested: (1) biomass production of below- and aboveground plant components of the exotic tree species is higher than that of the natives, resulting in a higher competitiveness of the exotics; (2) the exclusion of root competition has a positive effect on the biomass production of the inferior native species; and (3) mixtures of native and exotic species yield a higher biomass production than the respective monocultures.Methods A pot experiment, containing about 2000 tree seedlings, was established. We investigated the biomass productivity and growth reactions of two native (Quercus robur L., Carpinus betulus L.) and two exotic tree species (Prunus serotina Ehrh., Robinia pseudoacacia L.) in different intra- and interspecific, competitive situations with and without the influence of root competition.Important findings The biomass production of both exotic species was significantly higher and led to a strong competitive advantage, resulting in a biomass decrease of the less competitive native species. The high belowground biomass of both exotic species had a negative effect on the biomass production. The competitive pressure of exotic tree seedlings on the native ones was largely driven by root competition. Furthermore, mixtures of native and exotic tree species had a higher productivity than their growth in monocultures would have predicted. Competition was lower for exotic species in mixtures with the less productive native species compared to the competition in monocultures or in mixture with the other highly productive exotic species. Accordingly, both highly competitive exotic species produced less biomass in mixture with each other compared to monocultures. Despite the significantly higher biomass of P. serotina in all mixtures and in monoculture, R. pseudoacacia seemed to be the dominating species. Due to its strong root competition, R. pseudoacacia significantly reduced the biomass production of P. serotina .     

The relationship between competitive ability and yield stability in an old and a modern winter wheat cultivar

This study was conducted to determine if there were differences in competitive ability and yield stability on the growth of an old landrace of winter wheat (Triticum aestivum), Pinglang 40 (PL40), and a modern cultivar, Changwu135, (CW135), which differed in time of cultivar release, height, shoot and root biomass. A second aim was to investigate whether there is a relationship between competitive ability and yield stability. One pot and two field experiments were conducted to monitor changes in the competitive ability and yield stability of an old and a modern winter wheat cultivar grown in monoculture and mixtures using a de Wit replacement series. The pot study was conducted at two soil moisture levels: (a) well watered (WW), soil maintained at 85% field capacity, and (b) moderate drought (MD), soil maintained at 55% field capacity. The field experiments were conducted in 2 years that were drier than the average. In the second field experiment 40 mm of irrigation was applied to half of the plots at jointing, booting and anthesis. The results were similar in the pot and field experiments. In the mixture, the old cultivar PL40 had a greater relative yield with a larger number of spikes per plant when compared with those of the modern cultivar CW135. The dry matter per stem of CW135 tended to decrease with the increasing proportion of PL40, indicating a lower competitive ability of the modern cultivar than that of the old cultivar. The superior competition of PL40 was primarily due to the higher plant height, larger leaf area index, greater tillering capacity and larger root system. Our results showed that the modern cultivar CW135 produced a higher grain yield, yield components (except spike number), water use efficiency (WUE_g) and harvest index under both water regimes in monoculture. However, the reduction in grain yield of CW135 when subjected to water-limited conditions was less than that of PL40 in the pot and field experiments. The greater grain yield of the CW135 was associated with a higher harvest index, thousand-kernel-weight and a lower root:shoot ratio. Water consumption over the entire growing period was significantly lower in CW135 under all soil moisture conditions, and the main difference in water consumption between the two cultivars was observed before anthesis. Post-anthesis accumulation of dry matter was greater in CW135 under water-limited conditions, but there was no difference between cultivars when water was adequate. The dry matter remobilization and contribution to grain yield of CW135 was lower than that of PL40. The results of the present study demonstrated that the higher competitive ability in the old landrace led to an increased sensitivity to environmentally-induced stress. As a result, there was a greater loss in grain yield by the old cultivar when the water supply was unfavorable. In addition, the differences in the life history strategy between the old and modern cultivars imply that reducing competitive ability in the modern cultivar has led to increased yield of the crop population and greater yield stability.     

The Effect of Grain Number per Ear (Sink Size) on Source Activity and its Water-Relations in Wheat

Blum, A., Mayer, J. and Golan, G. 1988. The effect of grainnumber per ear (sink size) on source activity and its water-relationsin wheat.–J. exp. Bot. 39: 106–114. Work was done to evaluate the nature of sink-source relationshipsin wheat (Triticum aestivum L.), when the strength of the sinkwas modified by the removal of half of the grain from the earat about anthesis. The main hypothesis was that sink-sourcerelationship would be modified by water stress and that a weakersink would improve the drought resistance of the source. Two experiments were performed. The first experiment evaluatedthe effect of de-graining in two wheat varieties grown in thefield. The second experiment (in the greenhouse) evaluated theeffect of de-graining in plants subjected to water stress afteranthesis by immersing the root system in a solution of polyethyleneglycol (6000), as compared with non-stressed controls. In bothexperiments measurements were performed after de-graining toprovide data on leaf gas exchange, leaf water potential, osmoticadjustment of leaves and ears (greenhouse), the percent of stemweight loss as an index of stem reserve mobilization, finalroot weight (greenhouse) and ear weight components. De-graining caused a decrease in flag leaf stomatal conductance,carbon exchange rate (CER) and transpiration and an increasein flag leaf water potential. These effects were stronger withwater stress. De-graining did not affect osmotic adjustmentin the flag leaf but induced better adjustment in glumes andawns. De-graining decreased the percent of stem weight lossand increased final root weight, especially under drought stress. A weaker sink was, therefore, considered to improve plant droughtresistance in terms of the maintenance of higher leaf waterpotential, a larger root, a better osmotic adjustment in theear and, possibly, increased flag leaf longevity. The ‘cost’of this improved drought resistance was in reduced flag leafCER and reduced stem (and root?) reserve mobilization. Key words: Drought resistance, carbon exchange rate, stomata, transpiration, osmotic adjustment, leaf water potential, root, awns, yield     

EFFECTS OF ROOT PRUNING AT THE REGREENING STAGE ON DROUGHT TOLERANCE AND WATER USE EFFICIENCY OF WINTER WHEAT IN LATE GROWING STAGE

 通过盆栽试验研究了返青期根修剪对冬小麦(Triticum aestivum)后期耐旱性及水分利用效率的影响。在返青期设置了两个根修剪处理: 1)小剪根, 在植株一侧切去部分侧生根; 2)大剪根, 在主茎四周切去部分侧生根。不剪根者设为对照(CK)。研究结果显示, 两个根修剪处理均显著减少了小麦的根系, 但对根冠比没有显著影响。在花期, 两个根修剪处理的小麦旗叶的叶绿素荧光参数最大光化学效率(The maximum photochemical efficiency of PSⅡ, F_v/F_m)、 PSⅡ潜在活性 (PSⅡ potential activity, F_v/F_o)、实际光化学量子产量(Effective PSⅡ quantum yield, Φ_PSⅡ)、表观光合电子传递速率(Apparent rate of photosynthetic electron transport, ETR)、光化学淬灭系数( Coefficient of photochemical quenching, q_P)和非光化学淬灭系数(Coefficient of non-photochemical quenching, NPQ)值, 在停止供水7 d后, 均显著高于对照, 这表明根修剪小麦的耐旱性强于对照, 因此在干旱胁迫下有较高的光化学活性。小剪根处理在高水条件下对小麦产量无显著影响, 而在中度干旱条件下显著提高了小麦的产量, 因此, 小剪根处理显著提高了小麦的抗旱系数; 小剪根处理在高水分处理(土壤水分含量为田间持水量的85%)和中度干旱胁迫处理(土壤水分含量为田间持水量的55%)条件下, 均显著提高了小麦的水分利用效率。但大剪根处理由于严重影响了群体数量和产量, 水分利用效率和抗旱系数均没有提高。可见, 适当地减少根系有助于小麦的耐旱性和水分利用效率的提高。     

塔克拉玛干沙漠腹地梭梭幼苗根系分布特征对不同灌溉量的响应

在塔克拉玛干沙漠腹地,采用分层分段挖掘法对不同灌溉量条件下(每株每次灌水35、24.5和14 kg)梭梭(Haloxylon ammodendron)幼苗根系的分布特征进行了研究。结果表明: 1)随着灌溉量的减少,梭梭幼苗根系生物量的分布格局有向深层发展的趋势,在不同灌溉量条件下地下垂直各层生物量与土壤垂直深度呈显著的负对数关系;2)各灌溉量梭梭幼苗的最大水平根长为垂直根长的2倍,但不同灌溉量根系生物量的水平分布趋势一致;3)吸收根生物量的垂直分布与土壤含水量的垂直变化基本一致,均呈“单峰型”曲线,但灌溉量不同,吸收根生物量峰值在土壤中出现的位置也不同,随着灌溉量的减少,吸收根集中分布区有向深层发展的趋势;4)根长、根表面积和根体积随着土壤深度的增加均呈“单峰型”曲线,灌溉量愈小,根长、根表面积和根体积的峰值愈位于土壤的深层;5)根冠比和垂直根深与株高之比随着灌溉量的减少而呈增加的趋势。