水分胁迫下持绿型玉米根系形态及根系活力的研究

在盆栽条件下,研究开花期和灌浆期干旱胁迫对持绿型玉米丹598和普通玉米黄早四根系形态及其活力的影响。结果表明,持绿型玉米丹598具有较长的总根长、较大的根表面积、根体积、根干重、根冠比及根系还原力,与普通玉米黄早四相比,水分胁迫下上述指标的降幅较小。在干旱条件下,持绿型玉米丹598能保持较好的根系形态和较高的根系活力。     

不同耐旱型玉米自交系冠层光合及产量对生殖生长期干旱胁迫的响应

在PVC管栽和大田条件下,采用裂区试验设计,主区为玉米自交系、裂区为水分处理,测定玉米冠层光合和产量等指标。结果表明,与对照(CK)相比,干旱胁迫(WS)处理下冠层叶色值(SPAD)、光合速率(Pn)、蒸腾速率(Tr)和叶面积指数(LAI)均呈下降趋势,耐旱性较强的黄早四(HZS)平均降幅小于耐旱性较弱的CML58,其SPAD和LAI的降幅较高期(R3)出现早于CML58(R5);干旱胁迫后,水分利用效率(WUE)呈升高趋势,HZS平均升幅高于CML58。HZS的SPAD、Pn、Tr、WUE、LAI、单株粒重、收获指数和群体产量均高于CML58。与CK相比,WS处理下HZS群体产量平均降幅低于CML58。综上,耐旱性较强的玉米自交系冠层光合参数对生殖生长期干旱胁迫响应相对滞后,可在干旱胁迫后维持相对较高的光合性能、水分利用效率和叶面积指数,促进植株干物质转化与子粒建成,最终获得较高产量。     

不同耐性玉米自交系苗期根系对低钾胁迫的生物学响应

通过水培试验,以典型耐低钾玉米自交系90-21-3和低钾敏感玉米自交系835为试材,分别于4、6、7、9和10叶期测定玉米根形态、根系还原力、伤流量和干物质积累量,研究不同耐性玉米自交系苗期根系对低钾胁迫的生物学响应。结果表明,低钾胁迫下,耐低钾玉米自交系90-21-3表现为根长增幅大,根表面积、根体积降幅小,根平均直径降幅大。与低钾敏感玉米自交系835相比,低钾胁迫下耐低钾玉米自交系90-21-3的根系相对发达、根系活力强、伤流量大及干物质积累量较大。     

苗期大豆根系及地上部性状与耐旱性的关系

选用耐旱性较强的野生大豆SNWS0048和综合性状优良但不耐旱的育成品种晋大73为亲本,构建回交自交系(BIL)群体。连续2 a在人工控制环境下,检测不同水分条件下该大豆群体的苗期根系及地上部性状,采用相关及通径分析研究了大豆根系及地上部性状与耐旱性的关系,同时探讨了这些性状的遗传特性。结果表明:在干旱胁迫下株高、茎重、根长和根重均有所下降,根冠比有所升高。干旱胁迫下的耐旱系数与所有性状呈正相关,其中与主根长、根重、根冠比极显著相关,与茎重显著相关,与株高相关不显著。通径分析进一步表明正常供水条件下根干重对大豆耐旱性有重要影响,而干旱胁迫条件下根冠比对大豆耐旱性的影响较大。     

耐低磷胁迫下玉米自交系幼苗的生长及磷素分配特征

选取耐低磷型玉米自交系QXN233和低磷敏感的QXH0121为材料,研究低磷、正常施磷、高磷3个生长条件下两个自交系幼苗的生长及磷素的分配情况。结果表明,在低磷和正常施磷条件下,自交系QXN233的地上部、根系与整株干重均显著高于QXH0121。低磷条件下,两个自交系根部形态差异较大,QXN233的根长、根表面积、根体积、根尖数均大于QXH0121,且QXN233的侧根数有所增加,推测其通过侧根的大量发育,增加根系表面积与根际环境的接触,促进根系对磷素的吸收。低磷条件下QXN233具有较小的根冠比,其地上部的磷素分配比例更高,表明QXN233能够吸收并输送更多的磷到地上部,从而使植株能够在低磷条件下更好地生长。     

黑土不同耕层厚度对玉米根系形态空间分布及其产量的影响

在重建不同厚度黑土层的定位模拟试验区开展免耕玉米大豆轮作试验,设3个黑土耕层厚度(10、20和30 cm),探究不同耕层厚度对玉米生育期间的根系形态及其产量影响。研究表明,玉米产量对不同耕层厚度反应敏感,30 cm耕层厚度处理玉米产量最高,比20 cm和10 cm耕层厚度显著高12.5%和24.1%,且玉米根系分布对耕层厚度响应差异明显。30 cm耕层厚度显著影响玉米0～10 cm土层根重密度,对10～30 cm土层根重密度及不同土层根长密度和比根长影响不明显。     

套作弱光胁迫对大豆苗期根系形态和生理活性的影响

研究玉米-大豆带状套作弱光环境下大豆苗期根系形态特征、生理特性和生物量积累,明晰苗期大豆根系对套作荫蔽的响应规律,筛选适宜玉米-大豆带状套作的大豆品种,为改良大豆对荫蔽胁迫的适应能力提供理论依据。以NTS1007、桂夏3号和南豆12等3个根系特征不同的大豆品种(系)为试验材料,在盆栽试验条件下,采用挖掘法考察根系形态特征,并对根系活力、表面积、伤流量和生物量积累等指标进行测定和分析。结果表明,与单作相比,玉豆带状套作下大豆主根长和侧根长均显著下降,侧根下降81.8%,主根下降42.8%,侧根下降更为明显;根系可溶性糖含量显著下降,导致根系活力降低,伤流量减少;大豆根系表面积和活跃吸收表面积显著减小,降幅均与一级侧根总长度的降幅呈极显著正相关;大豆植株生物量显著下降,其中地下部下降55.2%,地上部下降37.9%,根冠比减小。不同品种(系)大豆根系对套作的响应程度不同,南豆12的主根长、一级侧根长、根体积降幅最小(33.9%、74.4%、65.3%);桂夏3号的根系表面积和生物量降幅最大(67.1%、48.3%);NTS1007则根冠比、根系活力和伤流量冠比降幅最大(35.4%、39.2%、38.9%)。套作遮荫条件下大豆根系的伸长生长比根系生理性状更能够准确地反映植株根系生长状况,根系长度可作为判定对荫蔽胁迫适应能力的一个重要指标。南豆12在玉米-大豆套作下能够更为合理地分配同化产物,减小荫蔽胁迫对根系形态建成和生理活性的抑制作用,保证根系生物量积累。     

水分胁迫对槟榔幼苗根系形态与活力的影响

以槟榔为试验材料,采用盆栽法研究土壤不同相对含水量对槟榔幼苗根系形态和部分生理特性的影响。结果表明:(1)干旱处理使槟榔根系生物量及根冠比增加,叶片生物量下降,各器官中水分含量差异不显著。(2)干旱处理主要影响槟榔根系的数量、长度和粗度,从而影响根系表面积与体积,主要表现为:根长为0~5 cm的根系数量及单株总根数降低,根长大于10 cm的根系数量增加;根系表面积及根系体积在不同根段均以正常处理最高,而根系表面积大于6 cm2和根系体积大于0.5 cm3根段随水分含量的增加均呈下降趋势。(3)干旱处理对槟榔根系活力的影响为前期大于后期,随干旱程度的增加,根系活力下降越大。此结果表明槟榔主要通过调整根系数量、长度及粗度来适应干旱的环境条件,但干旱又明显抑制了槟榔的生长。     

玉米自交系根系对低钾胁迫的响应

通过大田试验,研究15个玉米自交系幼苗在正常供钾和天然低钾下的根形态特征、干物质积累和钾积累量的变化,探讨玉米自交系根系对低钾胁迫的响应。结果表明:低钾胁迫下,不同玉米自交系根长增加,根表面积、根体积减小,根变细;不同玉米自交系根部及地上部的干物质积累量及钾积累量在低钾胁迫下表现出不同程度的降低;ZD-2、91-2、099和90-21-3的耐低钾能力相对较强,ZD-1、D937、8112和835对低钾胁迫较为敏感。     

不同生育期水分胁迫对水稻根系生长及产量的影响

研究水分胁迫对水稻根系生长和产量的影响。以桂两优2号为材料,通过聚乙二醇（PEG-6000）模拟不同程度的水分胁迫,在水稻分蘖盛期和抽穗扬花期分别水分胁迫16 d,然后恢复正常供水。水分胁迫及复水10 d后测定水稻根系形态、根活力和干物质,成熟期测定产量。结果表明：分蘖盛期和抽穗扬花期适度的水分胁迫均能提高水稻根系活力;处于不同生育期的水稻根系对干旱的耐受程度不同,在分蘖盛期水分胁迫期间,轻、中度水分胁迫对水稻根长、根表面积、根体积的生长具有促进作用,复水后,促进效果不显著;而在抽穗扬花期水分胁迫期间,     

Development and Distribution of Root System in Two GrainSorghum Cultivars Originated from Sudan under Drought Stress

Abstract

The difference in rooting pattern between two grain sorghum cultivars differing in drought tolerance was investigated under drought stress. The cultivars, Gadambalia (drought-tolerant) and Tabat (droughtsusceptible), were grown in bottomless wooden or acrylic root boxes to examine root parameters. Gadambalia consistently exhibited higher dry matter production and leaf water potential than Tabat under drought stress in both root boxes. In the experiment with wooden root boxes, under a drought condition, Gadambalia extracted more water from deep soil layers (1.1-1.5 m), which was estimated from the reduction in soil water content, than Tabat. This was because Gadambalia had a significantly higher root length density in these soil layers. The high root length density was due to enhanced lateral root development in Gadambalia. In the other experiment with acrylic root boxes, though total root length in the upper soil layer (0-0.5 m) was declined by limited irrigation in both cultivars, the reduction in Gadambalia was moderate compared with that in Tabat owing to the maintenance of fine root growth. Unlike Tabat, Gadambalia had an ability to produce the nodal roots from higher internodes even under drought, which resulted in the high nodal root length of Gadambalia. The growth angle of nodal roots was significantly correlated with root diameter, and the nodal roots from the higher internodes had large diameters and penetrated into the soil more vertically. These results indicate that the responses of roots (i.e. branching and/or growth of lateral root, and nodal root emergence from higher internodes) to soil dryness could be associated with the drought tolerance of Gadambalia.     

土壤剖面硝态氮非均匀分布条件下小麦根系生长和氮素吸收特征

为探讨土壤硝态氮非均匀分布条件下小麦根系生长及氮素吸收特征,选用石麦15、衡观35、H10和L14等4个小麦品种为材料,进行土壤分层培养试验,模拟土壤剖面中上下层硝态氮空间分布差异,测定和分析了小麦根系长度、直径、分布等形态学特征及植株氮素含量和累积量。结果表明,当土壤中硝态氮施用量上层较低、下层较高时,小麦植株根系总长和表面积在上下土层中分布比值降低,根系趋向下层土壤生长。上下层土壤中硝态氮施用量均较高时,上下层土壤中的根系总长和表面积比值较大,根系趋向上层土壤生长。土壤剖面不同层次中硝态氮供应非均匀条件下,小麦根系发育呈现明显的可塑性反应。小麦根系总长和表面积以及直径≤0.15mm的细根长(占整个根系的比重很大)与植株地上部氮含量和氮素积累量极显著正相关,与土壤中硝态氮含量极显著负相关。     

Root architecture of sorghum genotypes differing in root angles under different water regimes

Plant root architecture offers the potential for increasing soil water accessibility, particularly under water-limited conditions. The objectives of this study were to evaluate the root architecture in two genotypes of sorghum (Sorghum bicolor (L.) Moench) differing in root angles and to assess the influence of different deficit irrigation regimes on root architecture. The response of two sorghum genotypes, ‘Early Hegari-Sart’ (EH; steep root angle) and ‘Bk7’ (shallow root angle) to four irrigation treatments was investigated in two replicated outdoor studies using large pots. The results indicated that EH possessed steeper brace and crown root angles, fewer brace roots, greater root biomass, and root length density than Bk7 at deeper soil depths (i.e., 15–30 and 30–45 cm) compared with a shallower depth (i.e., 0–15 cm). Across the soil profile, EH had greater root length density and length of roots of small diameter (<1 mm) than Bk7. Accordingly, EH showed more rapid soil-water capture than Bk7. Different levels of irrigation input greatly affected root architecture. Severe deficit irrigation (25% of full crop transpiration throughout the season) increased the angle and number of crown roots, root biomass, and root length density compared with 75 and 100% of full crop transpiration treatments. Consequently, root system architecture can be effectively manipulated through both genotypic selection and irrigation management to ensure optimal performance under different levels of soil available water.     

No-Tillage Enhanced the Dependence on Surface Irrigation Water in Wheat and Soybean

Abstract

No-tillage often affects crop root development due to the higher mechanical impedance to root elongation, resulting in yield reduction under an unfavorable rainfall pattern, such as drought. In this study, we analyzed the changes in water source of wheat and soybean under drought stress in a continuous no-tillage field. Deuterium-labeled irrigation water was applied at different growth stages of crops to analyze their water uptake pattern. Mechanical impedance of the surface soil was 3.5 and 4.4 times higher in the no-tillage than in the conventional tillage under wet and drought conditions, respectively. Root length density and root branching index (the length of lateral roots per unit axile root length) of soybean in the surface soil layer were higher in the no-tillage field. This indicates that the increased branching by the higher mechanical impedance of undisturbed surface soil causes roots to accumulate in the surface soil layer. The deuterium concentration in the xylem sap of both crops was significantly higher in the no-tillage than in the tillage under a drought condition. This indicates that the crops in the no-tillage field depend highly on the newly supplied easily accessible water (irrigation water and/or rainfall) as compared with those in the conventional tillage field under a limited water supply. In conclusion, enhanced surface root growth in the no-tillage condition would result in higher dependence on surface supplied irrigation water than in the conventional tillage under drought.     

Responses of Root Growth to Moderate Soil Water Deficit in Wheat Seedlings

Abstract

In the field, plants show better root growth in drying soil than in wet soil. However, the root growth enhancement has not been demonstrated clearly in the laboratory. In this study, the root growth response of wheat seedlings to moderate soil water deficits was characterized quantitatively in an environment-controlled chamber. Germinated seeds of wheat were grown for 15 days in the soil with a water potential ranging from field capacity (FC) to approximately –0.08 MPa. Theleaf area decreased with reduction in soil water potential. By contrast, the root surface area increased upon reduction ofthe soil water potential to –0.04 MPa while it decreased significantly in soil with a water potential of –0.08 MPa. The increase in surface area was obvious in the roots with a diameter of 0.2 to 0.4 mm and larger than 0.7 mm. Root weight increased with the reduction of soil water potential to –0.04 MPa. While specific root length decreased significantly with the reduction of water potential to –0.06 MPa, the specific root surface area did not. Assimilatestransported from shoot might be used in roots to increae the surface area mainly by increasing the diameter rather than the length in response to a moderate soil water deficit in wheat seedlings. This might result from the drought tolerance mechanism of osmotic adjustment in roots.     

不同降雨条件对不同耐旱型大豆根系的影响

为了明确耐旱型大豆根构型的特异性,田间条件下,以不同耐旱型大豆为研究对象,探讨不同降雨条件对大豆根系特性的影响。结果表明:干旱胁迫降低了各时期大豆植株的根和地上部生物量;同一地点,R2和R4期取样,辽豆14的根和地上部生物量高于辽豆21。随着生育进程的推进,根冠比值逐渐增大;一般而言,V4~R4期,干旱胁迫提高了植株的根冠比。苗期干旱胁迫显著提高了大豆根长,但结荚期和鼓粒期干旱胁迫均降低了大豆根长、根表面积。大豆根长占比以细根为主,平均根直径≤2.5 mm的根长比例均在90%以上。根表面积占比也主要以细根为主,但大豆根体积分配比例较高的却主要是根系直径2.5 mm的粗根。研究结果进一步丰富了耐旱基因型大豆根器官应答干旱胁迫的理论知识,对大豆抗旱生产栽培具有重要的理论价值和实践意义。     

Effects of Subsoiling to the Non-tilled Field of Wheat-Soybean Rotation on the Root System Development,Water Uptake,and Yield

Abstract

We introduced subsoiling to a field of wheat-soybean rotation where no-tillage practice had been conducted for five years and whose yield tended to decrease or stagnate. By subsoiling a half of each plot just before wheat sowing, treatments of tillage/no-tillage × subsoiling/no-subsoiling were established. Root distribution, shoot growth, water uptake and yield of both crops were examined to elucidate whether the subsoiling improves the productivity such as shoot biomass and yield through the modification of root system development, and how differ the effects of subsoiling between tilled and non-tilled fields. In wheat, roots were less concentrated in surface (0 ? 5 cm) layer in no-tillage, and distributed more in deep (20 ? 25 cm) layer of the soil. Deuterium labeled heavy water analysis revealed that the subsoiling enhanced water uptake from the deep soil layer in the no-tillage field. Both the no-tillage and subsoiling showed positive and significant effect on total biomass and yield. The effect of subsoiling must be related to water supply by deep roots in spring. In soybean no-tillage significantly increased the productivity, but subsoiling did not though distribution of the roots was modified by both practices. Soybean in non-tilled accumulated roots in the surface soil layer, but subsoiling did not significantly modify the root distribution especially in the deep soil layer. Water uptake trend and yield was thus not changed significantly by subsoiling. Subsoiling in the non-tilled field increased rooting depth and showed the possibility of braking yield stagnation in long-term no-tillage cultivation in wheat, but not in soybean.     

东北黑土区高产大豆R5期根系分布特征

利用钻土法及根系扫描分析系统研究不同产量类型大豆R5期根系在植株周围、株间及垄间土壤中的空间分布特征。结果表明：高产类型大豆根冠比较高，而且单位根长、根表面积的地上部干物质较高。根干重不仅在根系较集中的植株周围及株间0 ~ 30 cm的土层，而且在较深的土层（> 30 cm）中都有较多的分布；根长在植株周围的0 ~ 45 cm土层范围内表现出一定的优势。直径 < 1.0 mm的细根形成了根系的主要部分，根长差异的主要原因不是细根比例的大小，而是细根数量的多少。除株间0 ~ 15 cm土层外，高产大豆各土层的根/土体积比较高。