镧浸种对盐胁迫下小麦幼苗生长及其生理特征的影响

通过水培方式研究了0、25、50和100 mg/L硝酸镧浸种对盐胁迫条件下小麦品种临抗11和临优2069根系及幼苗生长的影响.结果表明:(1)与对照组相比,盐胁迫处理小麦幼苗植株矮,根系短,叶片叶绿素含量、根系活性吸收面积以及SOD和CAT活性明显降低,叶片MDA与Pro含量水平显著上升;在钠离子浓度相同的情况下,Na2CO3对小麦生长的影响大于NaCl.(2)适当浓度硝酸镧浸种处理增加了盐胁迫下小麦幼苗的株高、总根长、根系活性吸收面积及SOD和CAT活性,且各指标在盐胁迫下增加幅度高于正常水分处理.(3)2个小麦品种对镧处理的敏感程度存在差异,不同小麦品种及不同盐胁迫下最适的镧浸种浓度不同.研究发现,适当浓度镧浸种能有效缓解盐胁迫对小麦幼苗的伤害,具有显著促进小麦根系生长、培育壮苗的作用.     

根土空间对高粱根系生理特性及产量的影响

采用尼龙袋（允许水分和养分自由通过）装土栽培作物的方法,研究了根系生长空间对高粱根系生理特性及产量的影响.结果表明,限制根系生长空间影响了高粱的生长,不同程度地降低了高粱的株高、叶面积、花后旗叶SOD及POD活性、总根长、根系吸收面积、根系与地上部干重、养分吸收量及最终产量,但增加了根系活力及活性吸收面积占总吸收面积的百分数.施肥有利于改善高粱根系在空间胁迫下的生长,增加根系吸收面积和活力,促进根系对养分的吸收,在一定程度上延缓根系生长空间不足所造成的不良影响.     

不同有机酸对铅胁迫小麦幼苗的缓解作用

研究了在铅胁迫条件下,加入外源有机酸对小麦铅毒害的缓解效应。结果表明,低浓度的草酸和乙酸能增加铅胁迫小麦叶绿素含量,不同程度地提高SOD、CAT、POD活性,降低MDA含量,而高浓度草酸和乙酸及柠檬酸对此则无明显的缓解作用;乙酸处理减少根系活跃吸收面积,柠檬酸能明显提高根系活力。草酸对铅胁迫的缓解效果最明显。     

长期定位施肥土壤中AM真菌对寄主植物的侵染状况

分别于2003年9月和2004年5月在莱阳农学院长期(26年)定位施肥试验田采集玉米和小麦根系,以测定不同施肥处理对丛枝菌根(AM)真菌侵染状况的影响。结果表明长期定位施氮(N)肥显著降低了AM真菌对寄主植物的侵染率(MCP)、丛枝着生率(ACP)、单位根长泡囊数(NV)和侵入点数(NE)。高N处理的小麦MCP低于低N处理,高N处理的玉米ACP低于低N处理。长期定位施有机肥,尤其是高有机肥处理显著降低了MCP、ACP和NE。有机肥和N肥配施也降低了MCP、ACP、NV和NE,以高有机肥和高N肥配施处理的降低效应最大。除小麦根系NV外,长期定位NPK配合施用降低了玉米和小麦的MCP、ACP、NV和NE。其中,以NP处理的玉米ACP、小麦的MCP和ACP最低。另外,低有机肥与N肥配施和NPK配施处理条件下玉米MCP高于小麦。结论认为不同施肥体制对作物菌根生长发育及其结构具有不同影响,而且有机肥和N肥在影响AM真菌侵染方面存在互作。     

干旱胁迫对小麦幼苗根系生长和叶片光合作用的影响

采用水培试验方法,以2个耐旱性不同的小麦品种(敏感型望水白和耐旱型洛旱7号)为材料,研究了干旱胁迫对小麦幼苗根系形态、生理特性以及叶片光合作用的影响,以期揭示小麦幼苗对干旱胁迫的适应机制.结果表明： 干旱胁迫下,2个小麦品种幼苗的根系活力显著增大,而根数和根系表面积受到抑制;干旱胁迫降低了望水白的叶片相对含水量,提高了束缚水/自由水,而对洛旱7号无显著影响;干旱胁迫降低了2个小麦品种叶片的叶绿素含量、净光合速率、蒸腾速率、气孔导度和胞间CO2浓度,但随胁迫时间的延长,洛旱7号的叶绿素含量和净光合速率与对照差异不显著;干旱胁迫降低了2个小麦品种幼苗的单株叶面积,以及望水白的根系、地上部和植株生物量,而对洛旱7号无显著影响.水分胁迫下,耐旱型品种可以通过提高根系活力、保持较高的根系生长量来补偿根系吸收面积的下降,保持较高的根系吸水能力,进而维持较高的光合面积和光合速率,缓解干旱对生长的抑制.     

干旱胁迫对小麦幼苗根系生长和叶片光合作用的影响

采用水培试验方法,以2个耐旱性不同的小麦品种(敏感型望水白和耐旱型洛旱7号)为材料,研究了干旱胁迫对小麦幼苗根系形态、生理特性以及叶片光合作用的影响,以期揭示小麦幼苗对干旱胁迫的适应机制.结果表明： 干旱胁迫下,2个小麦品种幼苗的根系活力显著增大,而根数和根系表面积受到抑制;干旱胁迫降低了望水白的叶片相对含水量,提高了束缚水/自由水,而对洛旱7号无显著影响;干旱胁迫降低了2个小麦品种叶片的叶绿素含量、净光合速率、蒸腾速率、气孔导度和胞间CO2浓度,但随胁迫时间的延长,洛旱7号的叶绿素含量和净光合速率与对照差异不显著;干旱胁迫降低了2个小麦品种幼苗的单株叶面积,以及望水白的根系、地上部和植株生物量,而对洛旱7号无显著影响.水分胁迫下,耐旱型品种可以通过提高根系活力、保持较高的根系生长量来补偿根系吸收面积的下降,保持较高的根系吸水能力,进而维持较高的光合面积和光合速率,缓解干旱对生长的抑制.     

根际通气状况对盐胁迫下棉花幼苗生长的影响

以溶液培养的棉花(Gossypium hirsutum)幼苗为材料,测定了不同盐胁迫程度和不同通气状况下棉花幼苗株高、根系体积、根系和茎叶生物量以及灰分含量的变化,以探索根际通气状况对盐胁迫下棉花生长的影响。结果表明,盐胁迫抑制棉花植株生长,表现为植株变矮、叶面积减小和干物质积累下降;根际环境通气不良也会导致棉花幼苗生长受抑制、干物质积累下降和矿质元素吸收减少等。进一步比较盐胁迫和根际通气状况及两者组合作用对棉苗生长的影响,发现盐胁迫对株高和总生物量的影响较大,而根际通气状况对根系体积、根系生物量、根冠比和矿质元素吸收的影响较大。总体表现为:盐胁迫对茎叶生长的不利影响较大,而根际通气状况对根系生长的不利影响较大。同时,在根际环境通气良好的条件下,不同程度盐胁迫导致的棉花幼苗株高、根系体积、叶面积、根系生物量和总生物量的变化程度远小于根际环境通气不良条件下的变化程度。实验结果表明,根际环境通气良好可以减弱盐胁迫对棉花生长发育的抑制作用,而根际环境通气不良则会加重盐胁迫的不利影响。     

盐旱复合胁迫对小麦幼苗生长和水分吸收的影响

为明确盐害、干旱及盐旱复合胁迫对小麦幼苗生长和水分吸收的影响,从而为盐害和干旱胁迫下栽培调控提供理论依据。以2个抗旱性不同的小麦品种(扬麦16和耐旱型洛旱7号)为材料,采用水培试验,以NaCl和PEG模拟盐旱复合胁迫,研究了盐旱复合胁迫下小麦幼苗生长、根系形态、光合特性及水分吸收特性的变化。结果表明,盐、旱及复合胁迫下小麦幼苗的生物量、叶面积、总根长与根系表面积、叶绿素荧光和净光合速率均显著下降,但是复合胁迫处理的降幅却显著低于单一胁迫。盐旱复合胁迫下根系水导速率和根系伤流液强度显著大于单一胁迫,从而提高了小麦幼苗叶片水势和相对含水量。盐胁迫下小麦幼苗Na~+/K~+显著大于复合胁迫,但复合胁迫下ABA含量却显著小于单一的盐害和干旱胁迫。因此,盐旱复合胁迫可以通过增强根系水分吸收及降低根叶中ABA含量以维持较高光合能力,这是盐旱复合胁迫提高小麦适应性的重要原因。洛旱7号和扬麦16对盐及盐旱复合胁迫的响应基本一致,但在干旱胁迫下洛旱7号表现出明显的耐性。     

硅对铜胁迫下小麦幼根细胞超微结构的影响

为探索硅对重金属铜胁迫下小麦的缓解作用,以矮抗58为供试材料,采用室内溶液培养法,研究不同浓度重金属铜(0、15、30 mg·L^-1)胁迫及铜胁迫下添加外源硅(50 mg·L^-1)对小麦幼苗生长、根系活力及根尖超微结构的影响.结果表明: 铜处理下,小麦幼苗根长、株高和根系活力均极显著低于对照(P＜0.01),加硅处理后小麦根长、株高和根系活力与单一铜处理相比均有所提高.铜胁迫下,小麦根尖细胞壁和细胞膜均遭到不同程度的破坏,细胞间空隙加大、细胞器消失;加硅处理后,虽然与对照相比,部分细胞和细胞器仍有变形,但细胞结构基本保持完好.综上,外源硅能在一定程度上缓解重金属铜对小麦幼苗生长及细胞组分的胁迫.
     

水杨酸对锌胁迫下小麦幼苗生长抑制的缓解效应

以小麦品种‘新麦18’为材料,采用室内水培实验研究了不同浓度水杨酸(SA)处理对300 mg.L-1锌胁迫下小麦种子萌发和幼苗生长的影响。结果表明:在Zn2+胁迫下,小麦种子的发芽势和发芽率、幼苗根长、芽长以及幼苗叶片的可溶性蛋白含量、根系活力显著降低,而脯氨酸和丙二醛(MDA)含量显著增加(P<0.05);外施SA显著提高了Zn2+胁迫下小麦种子的发芽势和发芽率,同时也使Zn2+胁迫7 d后的小麦幼苗的根长、芽长,幼苗叶片的脯氨酸和可溶性蛋白含量以及根系活力显著升高,膜脂过氧化产物MDA含量却显著降低(P<0.05)。由此可见,外施SA可通过提高小麦幼苗根长和芽长来增加幼苗根系活力,通过提高小麦幼苗可溶性蛋白含量、脯氨酸含量来维持细胞膜的稳定性,降低膜脂过氧化伤害程度,从而缓解了Zn2+胁迫对幼苗生长的抑制,并以14 mg.L-1外源水杨酸缓解效果最好。     

水分胁迫下AM真菌对沙打旺生长和抗旱性的影响

利用盆栽试验研究了水分胁迫条件下接种AM真菌对优良牧草和固沙植物沙打旺(Astragalus adsurgens Pall.)生长和抗旱性的影响。在土壤相对含水量为70%、50%和30%条件下,分别接种摩西球囊霉(Glomus mosseae)和沙打旺根际土著菌,不接种处理作为对照。结果表明,水分胁迫显著降低了沙打旺植株(无论接种AM真菌与否)的株高、分枝数、地上部干重和地下部干重,并显著提高了土著AM真菌的侵染率,对摩西球囊霉的侵染率无显著影响。接种AM真菌可以促进沙打旺生长和提高植株抗旱性,但促进效应因土壤含水量和菌种不同而存在差异。不同水分条件下,接种AM真菌显著提高了植株菌根侵染率、根系活力、地下部全N含量和叶片CAT活性。土壤相对含水量为30%和50%时,接种株地上部全N、叶片叶绿素、可溶性蛋白、脯氨酸含量和POD活性显著高于未接种株;接种AM真菌显著降低了叶片MDA含量;接种土著AM真菌的植株株高、分枝数、地上部和地下部干重显著高于未接种株。土壤相对含水量为30%时,接种AM真菌显著增加了地上部全P含量和叶片相对含水量;接种摩西球囊霉的植株株高、分枝数、地上部和地下部干重显著高于未接种株。水分胁迫40d,接种AM真菌显著提高了叶片可溶性糖含量。水分胁迫80d,接种株叶片SOD活性显著增加。菌根依赖性随水分胁迫程度增加而提高。沙打旺根际土著菌接种效果优于摩西球囊霉。水分胁迫和AM真菌的交互作用对分枝数、菌根侵染率、叶片SOD、CAT和POD活性、叶绿素、脯氨酸、可溶性蛋白、地上部全N和全P、地下部全N和根系活力有极显著影响,对叶片丙二醛和地下部全P有显著影响。AM真菌促进根系对土壤水分和矿质营养的吸收,改善植物生理代谢活动,从而提高沙打旺抗旱性,促进其生长。试验结果为筛选优良抗旱菌种,充分利用AM真菌资源促进荒漠植物生长和植被恢复提供了依据。     

Morpho-anatomical responses ofTrigonella foenum graecum Linn. to induced cadmium and lead stress

Effect of different concentrations of cadmium (0, 5,15, 30, 50 μg/g of soil) and lead (0,25, 50,100,200 μg/g of soil) on morphological and anatomical features ofTrigonella foenum graecum Linn, was studied at pre-flowering, flowering and post flowering stages. Morphological attributes, like number of leaves per plant, total leaf area of the plant and single leaf area, dry mass of stem, root and leaf, length of shoot, root and plant, size of stomata and stomatal pore, and the density of stomata on both epidermises were significantly reduced under metal stress at all the developmental stages. Trichome length on both epidermises increased while their density decreased under metal stress. Under cadmium stress, proportion of pith and vasculature decreased but cortex increased in the stem. Under lead stress, proportion of pith and vasculature increased but cortex decreased in the stem. In the root, proportion of vasculature and pith increased and cortex decreased in response to both cadmium and lead stresses. Dimensions of vessel element and xylem fibre in the wood of stem and root decreased under the cadmium and lead stresses. Decrease in density of vessel element in the stem and root with advancement of age was more pronounced in plants grown under cadmium and lead stresses.     

根区水肥空间耦合对冬小麦生长及产量的影响

利用管栽试验研究了根区不同湿润方式（整体湿润、上湿下干、上干下湿）、施肥方式（整体施肥、上层施肥、下层施肥）及其耦合对冬小麦不同生育期生长及产量的影响.结果表明：下层施肥方式显著降低了分蘖期冬小麦的株高和叶面积,而不同湿润方式对分蘖期株高和叶面积的影响不显著,拔节期水肥同区方式的株高大于水肥异区方式,表现出协同耦合效应.上干下湿方式和下层施肥方式显著降低了根系干物质量、地上部干物质量和总干物质量,上层施肥方式有利于增加冬小麦生物量,而上湿下干方式与施肥处理对地上部干物质量和总干物质量的耦合效应明显.水肥同区处理的根冠比高于水肥异区处理;上干下湿方式的水分利用效率显著高于整体湿润和上湿下干方式,水肥同区处理的水分利用效率高于水肥异区处理,但下层施肥方式的水分利用效率较低.与上干下湿方式相比,上湿下干和整体湿润方式的冬小麦单穗粒数分别增加了41.7%和61.9%,上层施肥和整体施肥方式的单穗粒数高于下层施肥方式,上湿下干方式与施肥处理对小麦产量及产量构成因素（除千粒重外）的水肥耦合效应明显.不同水肥处理主要通过影响单穗粒数来影响冬小麦产量.     

Responses of radish (Raphanus sativus) to drought stress

With this study the effects of water deficit on radish growth, dry mass production and partitioning, source–sink relations, physiological responses and accumulation of secondary metabolites in storage roots and leaves have been investigated. Three water stress treatments were applied: (Control) 100% of water holding capacity (WHC), (WS50) 50% of WHC, (WS30) 30% of WHC. Water stress was effectively acquired starting from 287 growing degree days (GDD) as demonstrated by the lower values of relative water content (RWC), higher leaf temperature and NIR‐based water indices values in water stressed conditions. Water stress reduced storage root dry weight by 27% at WS50 and 53% at WS30 as well as leaf dry matter accumulation (by 23% and 31% in WS50 and WS30, respectively), expansion (by 28% and 45% in WS50 and WS30, respectively) and specific leaf area (by 7% and 20% in WS50 and WS30, respectively) at 403 GDD. The increasing of leaf‐to‐root mass (L/R) and leaf area‐to‐root mass (LA/R) ratios indicated less dry matter allocation into storage organs under water stress conditions. Besides, water shortage increased leaf greenness as estimated by the higher soil–plant analysis development (SPAD) values (+14% and +20% on average for WS50 and WS30, respectively); other reflectance indices only partially confirmed SPAD readings. Substantially, water limitation did not significantly influence total anthocyanin content, ABTS‐radical scavenging activity and total free phenolic compounds in storage roots, as well as the total free phenolic compounds in leaves. Radish showed a strong plasticity in its adaptation to drought thanks to avoidance mechanisms such as constrained leaf development, increased leaf thickness and adjusted source–sink relationships.     

狭叶红景天幼苗对水分及遮阴的生长及生理生化响应

研究植物对水分和遮阴胁迫的响应及其生理机制对制定合理的栽培管理措施十分必要。以红景天属植物为研究对象,设置土壤含水量分别为田间持水量的80%(过湿水分)、70%(正常水分)、60%(轻度干旱)、40%(中度干旱)、20%(重度干旱)5个水分梯度;设置2个遮阴处理,以全光照(遮阴率为0)为对照、黑色遮阴网遮阴(遮阴率为85%),研究狭叶红景天生长及生理生化指标的变化特征。结果表明:在不同水分处理下,与对照相比,叶绿素含量、茎干重和茎重比(SMR)显著增加(P0.05),株高、总生物量、叶面积、叶干重、叶重比(LMR)、比叶面积(SLA)、叶面积比(LAR)和叶面积根干重比(LARMR)增加,根冠比和根重比(RMR)减少;随着干旱程度加剧,丙二醛(MDA)、脯氨酸(Pro)和可溶性糖(Ss)含量增加,超氧化物歧化酶(SOD)活性总体呈先增加后减小的趋势。在遮阴处理下,株高、SMR、SLA、LAR和LARMR显著增加(P0.05),叶绿素SPAD值和叶面积增加,总生物量、根干重、根冠比和LMR显著减少(P0.05),茎干重和叶干重减少,MDA含量显著增加,Pro含量略有下降,Ss含量减少。在水分胁迫下,狭叶红景天中度干旱时通过增加酶活性抵御伤害,重度干旱超过其阈值,SOD活性下降,植物体受到伤害,Ss可能是主要的渗透调节物质。在遮阴处理下,狭叶红景天通过增加SLA避免遮阴伤害。狭叶红景天在受到环境胁迫时会通过形态改变、调节MDA含量、抗氧化酶活性和渗透调节物质来保证自身正常的生长发育。     

氮肥运筹对免耕水稻根系生长、根际土壤特性及产量的影响

为探索氮肥运筹对免耕条件下水稻根系生长以及对根际土壤特性、产量的影响,以金优253为材料进行试验。结果表明：平衡施肥显著提高单株根系干重、根长、单株生物量、根半径、单株根表面积、根长密度及根系活力,实收单产高于重穗肥和重基肥处理,且与重基肥差异达95％的显著水平,主要是有效穗数、结实率的增加。平衡施肥显著提高0~10 cm土层的0~2 mm根际土壤有机质、碱解氮含量及脲酶、蔗糖酶活性。因此平衡施肥能明显促进免耕水稻根系生长和有效穗数的增加,对提高水稻产量具有促进作用。     

Maize root response to N in the greenhouse and field

Summary Root growth and morphology were compared between seven week old maize plants grown in the greenhouse and in the field. The plants were similar in shoot dry weight and the partioning of N and dry matter to roots were similar except for the field grown plants in 1983. Field grown plants had greater root mass per length and greater calculated diameter than greenhouse plants. Nitrogen fertilization decreased N and dry matter partitioning to the root system in all three environments.     

Modifications of the carbon and nitrogen allocations in the plant (Triticum aestivum L.) soil system in response to increased atmospheric CO2 concentration

The aim of this work was to examine the response of wheat plants to a doubling of the atmospheric CO₂ concentration on: (1) carbon and nitrogen partitioning in the plant; (2) carbon release by the roots; and (3) the subsequent N uptake by the plants. The experiment was performed in controlled laboratory conditions by exposing fast-growing spring wheat plants, during 28 days, to a ¹⁴CO₂ concentration of 350 or 700 L L^–1 at two levels of soil nitrogen fertilization. Doubling CO₂ availability increased total plant production by 34% for both N treatment. In the N-fertilized soil, the CO₂ enrichment resulted in an increase in dry mass production of 41% in the shoots and 23% in the roots; without N fertilization this figure was 33% and 37%, respectively. In the N-fertilized soil, the CO₂ increase enhanced the total N uptake by 14% and lowered the N concentration in the shoots by 23%. The N concentration in the roots was unchanged. In the N-fertilized soil, doubling CO₂ availability increased N uptake by 32% but did not change the N concentrations, in either shoots or roots. The CO₂ enrichment increased total root-derived carbon by 12% with N fertilization, and by 24% without N fertilization. Between 85 and 90% of the total root derived-¹⁴C came from respiration, leaving only 10 to 15% in the soil as organic ¹⁴C. However, when total root-derived ¹⁴C was expressed as a function of root dry weight, these differences were only slightly significant. Thus, it appears that the enhanced carbon release from the living roots in response to increased atmospheric CO₂, is not due to a modification of the activity of the roots, but is a result of the increased size of the root system. The increase of root dry mass also resulted in a stimulation of the soil N mineralization related to the doubling atmospheric CO₂ concentration. The discussion is focused on the interactions between the carbon and nitrogen allocation, especially to the root system, and the implications for the acquisition of nutrients by plants in response to CO₂ increase.Abbreviations N soil fertilization without nitrogen - N soil fertilization with nitrogen     

Activities and Toxicity of a Novel Plant Growth Regulator 2-Furan-2-yl-[1,3] Dioxolane

The effect of activities of three substituted dioxolanes on wheat growth were assessed under laboratory/field conditions. Compound III, 2-furan-2-yl-[1,3]dioxolane, demonstrated good activity in shortening germination time, improving root growth, and increasing drought and salinity tolerance. In a water medium, the three substituted dioxolanes increased root numbers. Under water-deficit stress all treated seeds germinated by the fifth day, whereas controls did not germinate until after 6.5 days. These dioxolanes increased root number and root length. Compound III was the most outstanding of the three, with an increase of 227% in root number, 234% in root length, and 295% in shoot dry mass. Under salinity stress, these dioxolanes significantly improved growth (promotion of root number and shoot dry mass), although they had no effect on tissue moisture content. Field trials showed that compound III promoted root growth, increased root fresh weight significantly, and maintained a normal yield under water-deficit conditions. It showed low mammalian and environmental toxicity in various toxicologic tests. Results of Salmonella typhimurium reversion assay with and without a S9 mixture and the chromosomal aberration assay revealed that it had no mutagenic potential under experimental conditions.     

Effect of Manipulated Rainfall on Root Production and Plant Belowground Dry Mass of Different Grassland Ecosystems

A field experiment was established to quantify the effects of different amounts of rainfall on root growth and dry mass of belowground plant parts in three types of grassland ecosystems. Mountain (Nardus grassland), highland (wet Cirsium grassland), and lowland grassland (dry Festuca grassland) ecosystems were studied in 2006 and 2007. Roofs constructed above the canopy of grass stands and gravity irrigation systems simulated three climate scenarios: (1) rainfall reduced by 50%, (2) rainfall enhanced by 50%, and (3) the full natural rainfall of the current growing season. Experimentally reduced amounts of precipitation significantly affected both yearly root increments and total root dry mass in the highland grassland. Dry conditions in 2007 resulted in considerable reduction of total belowground dry mass in highland and mountain grasslands. Although not all differences in root biomass of studied grasslands were statistically significantly, some also showed a decrease in root increment and in the amount of belowground dry mass in dry conditions.