外源硒对镉胁迫下绿豆幼苗生理特性的影响

采用水培试验方法研究不同浓度Se4+(0.8,1.6,2.4,3.2,4.0mg/L)对Cd2+(10,20mg/L)胁迫下绿豆幼苗超微弱发光及幼苗叶片中叶绿素、可溶性蛋白质和脯氨酸的影响。结果表明,随着胁迫时间延长,不同浓度Se4+对2种浓度Cd2+胁迫下绿豆幼苗的超微弱发光强度均呈现先升高后降低再升高的趋势,0.8,1.6mg/L的Se4+对2种浓度Cd2+胁迫下绿豆幼苗的超微弱发光强度均有促进作用,但是1.6mg/L浓度的Se4+对2种浓度Cd2+的缓解作用最佳。随着Se4+浓度的增加,2种浓度Cd2+胁迫下,绿豆幼苗叶片中叶绿素含量和可溶性蛋白质含量均呈现出先增加又减小的趋势,当Se4+浓度低于4.0mg/L时,叶绿素含量和可溶性蛋白质含量均高于单一Cd2+胁迫下叶绿素含量和可溶性蛋白质含量,且在Se4+浓度为1.6mg/L时达到最大。在10mg/L Cd2+胁迫下,随着Se4+浓度的增加,绿豆幼苗叶片中的脯氨酸含量先增加后减小,当Se4+浓度低于4.0mg/L时,脯氨酸含量高于单一Cd2+胁迫下脯氨酸含量,且Se4+浓度为1.6mg/L时脯氨酸含量达到最大;在20mg/L Cd2+胁迫下,随着Se4+浓度的增加,绿豆幼苗叶片中的脯氨酸含量逐渐降低,当Se4+浓度低于2.4mg/L时,脯氨酸含量高于单一Cd2+胁迫下脯氨酸含量,且Se4+的浓度为0.8mg/L时脯氨酸含量最大。研究表明在试验浓度范围内,Se4+浓度低于2.4mg/L时,对10,20mg/L Cd2+胁迫下的绿豆幼苗的毒害均有缓解作用,且浓度为1.6mg/L时缓解作用最佳。     

细胞分裂素类物质对玉米幼苗镉吸收和转运的影响

以玉米(Zea mays L.)幼苗为材料,采用水培试验研究了喷施细胞分裂素类物质6-苄氨基嘌呤(6-BA)和激动素(KT)对玉米镉吸收及转运的影响。结果表明,0.5mg/L镉处理条件下,细胞分裂素类物质能促进玉米幼苗的生长及其对镉的吸收和地上部镉的分配,对镉的转运系数影响较小。提高6-BA喷施浓度使玉米幼苗的生长量、镉吸收量及地上部镉分配增高,提高KT喷施浓度也使镉在地上部的分配比例增加,但当KT喷施浓度为70mg/L时玉米幼苗的生长量及镉的吸收量最高。表明细胞分裂素类物质可缓解镉对植物的毒害作用,提高植物提取水或土壤环境中的镉的效率,但其作用的最佳浓度因细胞分裂素类物质的种类不同而异。     

稀土镧对镉胁迫下玉米幼苗生长的影响

以水培法研究了重金属Cd对玉米幼苗的胁迫伤害及稀土La对Cd伤害的缓解作用。结果表明,在Cd胁迫伤害下,玉米幼苗生长受到抑制,主要表现为株高、主根长下降,叶面积锐减,茎叶、根的鲜重以及干重明显下降,随着Cd胁迫浓度的增加,玉米幼苗受伤害程度趋向严重。在玉米幼苗上喷施适量浓度LaCl3(20mg/L),能缓解Cd对玉米幼苗生长造成的伤害。     

镉胁迫对玉米生理特性的影响

试验研究不同浓度Cd胁迫对玉米生理特性的影响结果表明,玉米耐受性好,Cd胁迫下生长发育正常,0.2mg/L、0.5mg/L和1.0mg/L低浓度Cd处理玉米叶片叶绿素含量和过氧化物酶活性略升高,其最大应激浓度为1.0mg/LCd、毒性浓度为5.0mg/LCd;但随胁迫时间延长或胁迫浓度加大,玉米叶片叶绿素含量连续降低,根系活力降低后回复,而脯氨酸含量明显升高又回落,玉米表现出对低浓度Cd有一定抵抗能力,且Cd对玉米的毒害受时间和浓度双重因子的制约。玉米植株体内游离脯氨酸变化明显,因此脯氨酸可作为某些植物对重金属离子的同期抗逆性指标。     

钙对镉胁迫下玉米生长及生理特性的影响

采用溶液培养试验 ,研究不同的钙和镉处理对玉米植株生长、叶绿素含量、硝酸还原酶和ATPase酶活性以及叶片中丙二醛含量、活性氧清除酶系统活性的影响。结果表明 ,根部未供钙或叶面喷施CaCl2时 ,加镉处理玉米根、地上部生物量降低 ,根冠比加大 ;而根部供钙 ,植株生长较好 ,生物量较高 ,根冠比相对较小。营养液中加镉 ,玉米植株中镉浓度显著增加 ,根部镉浓度明显比地上部高 ,根中镉约占 65%～ 78% ,地上部镉占到 22%～35%左右。根部供钙比未供钙处理 ,根中镉含量虽没有显著性差别 ,但地上部镉浓度明显较低。叶片喷施CaCl2 4次比喷施 2次处理 ,地上部镉浓度增加。供钙明显增加了玉米植株中钙浓度。未供钙的玉米叶片叶绿素含量下降 ,但叶绿素a/叶绿素b比基本不变 ;加镉处理 ,玉米叶片叶绿素a、叶绿素b及叶绿素总量下降更甚 ,叶绿素a/叶绿素b比升高 ;叶面喷施CaCl2 ,叶绿素含量也较低。前期和后期根部供钙处理 ,叶绿素下降程度有所缓解。而根部一直供钙 ,玉米叶片中叶绿素a、叶绿素b和叶绿素总量明显提高。镉抑制了玉米植株叶片硝酸还原酶活性、ATPase活性 ;根中ATPase活性以及活性氧清除酶系统超氧化物歧化酶 (SOD)、愈创木酚过氧化物酶 (Gua POD)、抗坏血酸过氧化物酶 (AsA POD)、过氧化氢酶 (CAT)受镉的诱导而增加，叶片中丙二醛(MDA)含量升高。与未供应钙加镉处理相比，根部供钙加镉处理的玉米叶片硝酸还原酶活性、ATPase活性显著增加，也明显减轻了镉对根中ATPase活性、叶片中丙二醛含量、活性氧清除酶系统SOD，POD，CAT 活性的诱导效应。间隔供钙，在一定程度上缓解了镉的毒害，但是叶片喷施CaCl2，对减轻镉毒害无明显效果。因此在本试验条件下，根部供钙对缓解玉米镉毒害有重要作用。关键词:钙；镉；玉米；生理特性     

不同浓度硫处理下硒镉交互胁迫对水稻幼苗的生理特性影响

以淮稻6号为试验材料,采用水培的方法,研究了不同硫（S）浓度下（9、720mg·L-1）硒（Se）（5mg·L-1）和镉（Cd）（1、10mg·L-1）交互胁迫对水稻幼苗一些生理特性的影响,主要研究指标包括生物量、巯基物质含量和硒、镉含量。结果表明：（1）Cd对水稻幼苗各部分生长状况抑制能力大小不同,其对根长的抑制作用明显大于对茎长的抑制;（2）在无Se条件下,随着Cd浓度的增加,Cd对水稻幼苗生长的毒性不断增大,在加入一定浓度的Se后,Cd的毒性作用得到缓解;（3）在不同浓度S处理和Se、Cd交互胁迫下,随着S浓度增大,Cd对水稻幼苗毒性作用减轻;但高浓度的S处理反而对Cd与Se交互实验中Cd的毒性产生协同作用;（4）高浓度的S处理可以抑制水稻幼苗对Se的吸收;（5）巯基物质含量随着胁迫时间的增加呈先上升后下降的趋势。在Se、Cd交互实验中,低浓度S处理可以提高水稻幼苗中GSH和PCs的含量,从而促进植株体内重金属和PC的络合作用,缓减Cd对水稻幼苗的毒害。     

氟污染对玉米幼苗生长及生理特性的影响

为探讨氟污染对农作物的影响,以玉米为供试材料,采用砂基培养的方法,研究了不同浓度的氟（F）对玉米幼苗形态、生物量、光合参数、叶绿素含量、抗氧化酶活力以及丙二醛含量的影响。结果表明,与对照相比,低浓度 F（≤0.25 mmol·L^-1）对玉米幼苗生长无明显抑制现象;随着溶液中F浓度的增加,玉米幼苗生长显著受到抑制,叶长、株高生长变慢,叶面积减小;根系和地上部干物质积累下降;叶片中叶绿素合成受阻,光合速率降低;同时丙二醛（MDA）含量增加;过氧化物酶（POD）活性明显升高,而超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性均表现出一定的下降趋势。说明氟的存在不利于植物的正常生长,研究结果还为进一步揭示氟污染机理以及氟污染的综合治理提供了理论依据。     

驯化处理对海水胁迫下玉米幼苗生长特性的影响

为了探讨海水灌溉时提高植物耐受盐分胁迫的有效调节措施,以抗性玉米品种农大108为材料,研究了用20%和70%海水分别驯化的萌发种子和萌发期幼苗在生长后期50%海水胁迫过程中某些生理指标的变化。结果表明：在海水处理过程中,叶绿素和类胡萝卜素含量、光合速率和幼苗鲜质量明显下降,其中种子驯化能减弱胁迫对上述特性的不利影响,70%海水驯化种子缓解了对叶绿体色素和光合作用的破环,20%海水驯化种子减轻了幼苗鲜质量的降低;叶绿素a/叶绿素b(chla/chlb)、根系活力、幼苗干质量和根冠比明显上升,其中驯化处理有利于胁迫下幼苗根系活力和根冠比的升高,20%海水驯化种子促进了幼苗干质量和根冠比的增加,70%海水驯化幼苗对chla/chlb和根系活力的促进作用比20%海水驯化种子稍微明显一些。说明在不同发育阶段采取合理的驯化方式可以提高植物生长过程中对海水胁迫的适应能力,从而改善植物对灌溉海水的利用效率。     

Effect of heavy metals contamination on root-derived and organic matter-derived CO2 efflux from soil planted with Zea mays

The CO₂ efflux from loamy Haplic Luvisol and heavy metal (HM) uptake by Zea mays L. were studied under increased HM contamination: Cd, Cu, and Ni up to 20, 1000, and 2500 mg kg⁻¹ soil, respectively. Split-root system with contrasting HM concentrations in both soil halves was used to investigate root-mediated HM translocation in uncontaminated soil zones. To separate root-derived and soil organic matter (SOM)-derived CO₂ efflux from soil, ¹⁴CO₂ pulse labeling of 15-, 25-, and 35-days-old plants was applied. The CO₂ evolution from the bare soil was 10.6 μg C–CO₂ d⁻¹ g⁻¹ (32 kg C–CO₂ d⁻¹ ha⁻¹) and was not affected by HM (except 2500 mg Ni kg⁻¹). The average CO₂ efflux from the soil with maize was about two times higher and amounted for about 22.0 μg C–CO₂ d⁻¹ g⁻¹. Portion of assimilates respired in the rhizosphere decreased with plant development from 6.0 to 7.0% of assimilated C for 25-days-old Zea mays to 0.4–2.0% for 45-days-old maize. The effect of the HM on root-derived ¹⁴CO₂ efflux increased with rising HM content in the following order: Cd < Cu < Ni. In Cu and Ni contaminated soils, shoot and root dry matter decreased to 70% and to 50% of the uncontaminated control, respectively. Plants contained much more HM in the roots than in the shoots. A split-root system with contrasting HM concentrations allowed to trace transport of mobile forms of HM by roots from contaminated soil half into the uncontaminated soil half. The portion of mobile HM forms in the soil (1 M NH₄NO₃ extract) increased with contamination and amounted to 9–16%, 2–6% and 1.5–3.5% for Cd, Cu, and Ni, respectively. Corresponding values for the easily available HM (1 M NH₄OAc extract) were 22–52%, 1–20% and 5–8.5%. Heavy metal availability for plants decreased in the following order: Cd > Cu ≥ Ni. No increase of HM availability in the soil was found after maize cultivation.     

铅胁迫下小花南芥与玉米间作对根系分泌物 有机酸的影响

为了揭示Pb胁迫对间作和单作的超累积植物和作物根系分泌低分子有机酸的影响,研究设置400 mg·L?1Pb胁迫,采用水培曝气法试验,以玉米和小花南芥单作为对照处理,研究Pb胁迫下玉米和小花南芥间作对植物根系形态、根系分泌有机酸及Pb吸收的影响。结果表明:与单作相比,间作小花南芥情况下,玉米根系分泌物检测到乳酸;玉米分根条数、根表面积和根密度与单作相比分别增加60%、15%和42%,地下部和地上部干重生物量分别增加108%和75%,玉米地下部Pb含量下降44%;与单作相比,间作玉米条件下,小花南芥根系分泌物检测到乙酸和乳酸,小花南芥根系分泌物量与单作相比增加103%~1 700%,小花南芥地下部和地上部Pb累积量分别比单作增加49%和75%,转运系数增加22%。相关分析结果表明,单作小花南芥只有地上部Pb累积量与草酸显著相关,而间作小花南芥地下部和地上部Pb累积量与草酸、柠檬酸和苹果酸显著相关。研究表明超富集植物小花南芥与玉米间作体系,根系分泌的有机酸改变了Pb在小花南芥和玉米体内的累积特征,促进超累积植物小花南芥累积Pb,减少农作物玉米植株体内Pb含量。Pb胁迫下超累积植物小花南芥与玉米间作是一种可行的修复模式。     

Estimation, variation and importance of leaf curvature in Zea mays hybrids

Maize leaves are curved but this curvature cannot be described by a single system of equations based on conic sections. We made comparisons of curvature between hybrids, leaf positions and planting density using measures of maximum leaf height and leaf tip:maximum leaf height ratio. With these measures a modern hybrid released in 1991 (Pioneer 3394) shows less curvature compared with hybrids released in 1963 (Pioneer 3306) and 1936 (Pioneer 307). The greater uprightness of 3394's leaves was apparent for all leaves measured. Curvature is a plastic character. While all hybrids developed less curvature in higher density plantings the effect was greatest for 3394. 3394 had shorter, more lanceolate leaves with smaller leaf area, a lower estimated torque around the point of leaf attachment to the stem, and a significantly smaller auricle base and smaller angle between the leaf blade and auricle base. These results support suggestions that the pattern of curvature may be produced by the progression of irreversible bending during leaf development. We found no consistent relationships between differences in curvature and measurements of leaf midrib morphology or anatomy.A frequently used approach in modeling foliage area distribution by angle is to use an approximation provided by the angular distribution of an ellipsoid. We show that for leaves in this study this approach is biased and that a Richards function describes the cumulative frequency distribution of leaf area by inclination angle more effectively. The importance of an unbiased estimator is discussed in relation to the variation in photon flux density received by surfaces of different inclinations.     

市政污泥直接施用对玉米生长和品质的影响

[目的]研究市政污泥施用后对土壤和作物生长与品质的影响,为市政污泥的直接土地利用提供科学依据。[方法]以玉米为试验材料,利用田间试验研究了污泥不同的施用方式(沟施、撒施、表土下20 cm施用)和施用量(30,90,200 t/hm~2)对玉米生长和品质以及土壤重金属含量的影响。[结果]适量的污泥对玉米个体的生长有促进作用,施用量为30 t/hm~2时株高、单株生物量、叶片叶绿素含量、籽粒蛋白质含量均显著高于对照。表土下20 cm施用污泥在整体上较其他两种施用方式有更高的出苗率和籽粒产量,在施用量为30 t/hm~2时籽粒产量最高,为656.70 kg/667m~2,高出对照29.64%。3种施用方式下,土壤中的Cu,Zn,Pb含量及玉米籽粒中的Cu,Zn含量均随污泥施用量的增加而增加,而玉米籽粒中Pb含量与对照相比差异不显著,土壤和籽粒中重金属含量均未超过国家相关标准。以重金属浓度满足土壤环境质量标准为限制条件,推算出当地的市政污泥施用量为30 t/hm~2可以连续施用5 a。[结论]施用30 t/hm~2的污泥具有良好的效果和环境效应;为了降低污泥在土壤中的局部累积而导致的胁迫效应,表土下20 cm施用和地表撒施是相对较好的方式。     

氮施用量对夏玉米土壤水氮动态及水肥利用效率的影响

采用田间小区试验,监测夏玉米不同生长期土壤水分和硝态氮剖面含量变化,研究不同施氮量对其时空变化及籽粒产量、水肥利用效率的影响,探讨氮肥对水肥资源高效利用的调节作用。结果表明：不同施氮处理,土壤剖面水分和硝态氮随土壤深度的变化趋势基本一致,即表层50 cm土壤水分和硝态氮含量较高且呈降低态,50-110 cm相对较低且波动较小,灌浆期二者均达到最低值;各生长期表层50 cm土壤含水量呈不施氮处理均高于施氮处理,50-110 cm土层则相反;施氮能提高土壤硝态氮含量,土壤硝态氮运移受土壤水分状况和含量的影响,含量越高,向下移动越深;施氮能显著提高水分利用效率及籽粒产量,增产效果明显（增产28.52%-37.86%）,二者均以施氮240 kg/hm^2处理最高;随施氮量的增加籽粒产量及籽粒吸氮量和水分利用效率增幅均表现为先升高后降低之趋势,当施氮量超过240 kg/hm^2后,籽粒产量和水分利用效率提高并不显著;不施氮与施氮处理氮素生产力、氮肥利用率之间均存在极显著差异。在本试验条件下,从控制土壤硝态氮积累及取得较高的产量和氮素利用率综合考虑,夏玉米的适宜施氮量范围应控制在120-240 kg/hm^2较好。     

玉米生育期的海拔效应研究

为使高海拔地区的玉米生产布局和品种类型利用更加合理,采用作物生态学的田间试验方法,于2006～2007年间,在甘肃省和云南省各设5个试验点,研究了北、南异地不同玉米品种在不同海拔高度的生态效应.结果表明,在播期大体相同的条件下,玉米拔节期、抽雄期、成熟期随海拔的升高而相应延迟,即播种～拔节、拔节～抽雄、抽雄～成熟的"三段生长"时间相应延长.反映生育期长短的出苗～成熟天数与海拔之间呈0.01水平的正相关.本试验条件下,海拔每升降100 m,参试玉米品种的生育期延长或缩短4～5 d,株高和穗上叶数呈随海拔升高而降低趋势.     

Effect of pre-incubated sawdust-based cowdung on growth and nutrient uptake of Zea mays (L.) and on soil chemical properties

Summary A greenhouse soil culture experiment was set up to evaluate the effect of pre-incubation time (0, 2, 4, 6 weeks) of sawdust-based cowdung, prior to use, on the growth, dry-matter yield, and uptake of nutrients by Zea mays (L). The chemical properties of the soil (an Alfisol) were examined after the various treatments. The results indicated that incubation of cowdung for 4 weeks before planting time enhanced the growth and dry-matter yields of maize. Soil pH increased with the length of incubation while organic-C contents and cation exchange capacity remained unaffected. The length of pre-incubation enhanced the uptake of N and P but did not affect the uptake of K, Ca, Mg, and Na.     

铜绿假单胞菌对镉胁迫水稻苗期生长与镉积累的影响

稻米重金属污染是人们广泛关注的严重问题,微生物钝化是阻遏环境重金属进入生物循环的有效途径之一。为了解铜绿假单胞菌对苗期水稻镉污染的缓解效应,本文以无镉处理为对照,通过添加20μmol×L~(-1)镉的水培试验,研究了铜绿假单胞菌、载体A(硅藻土,粒径1~3 mm)、载体B(硅藻土,粒径3~6 mm)、载体C(活性炭,比表面积1 000 m~2×g-1)以及铜绿假单胞菌与载体制备的菌剂A、菌剂B和菌剂C对水稻生长、镉含量及镉积累量的影响。结果表明,20μmol×L~(-1)镉处理显著抑制了水稻根长、株高的生长和干物质积累,添加菌液及菌剂A、B、C后,水稻生长状况得到显著改善,总生物量比镉处理(0.523 g×株~(-1))提高38.5%~67.3%,以菌剂B处理的水稻生物量最高。水稻根、茎鞘、叶以及地上部镉含量显著降低,其中添加菌剂A、菌剂B、菌剂C及活性炭处理的水稻地上部镉含量分别比镉处理(101.3 mg×g~(-1))下降45.9%、47.9%、59.9%和59.9%,迁移系数降低16.7%、25.0%、33.3%和33.3%,富集系数减少48.1%、48.8%、58.8%和60.9%。添加活性炭、菌剂A和菌剂C处理的水稻单株镉积累量降低18.2%、9.5%和24.3%,添加菌剂B以及依次含有56.4 mL、45.3 mL、28.4 mL菌悬液的菌液A、菌液B和菌液C处理,其镉积累量依次增加15.0%、30.4%、14.9%、16.9%,说明菌株通过提高作物生物量增加了镉积累。综上,铜绿假单胞菌可显著促进镉胁迫水稻的生长,降低水稻的镉含量,抑制镉的迁移,降低水稻镉的有效性;菌剂A、B、C表现出良好的镉钝化能力,表明铜绿假单胞菌可为环境镉污染的生物修复提供新菌株。     

Effect of inoculation with Azotobacter chroococcum on nitrogenase activity of Zea mays roots grown in agricultural soils under aseptic and non-sterile conditions

Summary Inoculated and non-inoculated seedlings of Zea mays were grown in agricultural soils under aseptic and non-sterile conditions. Acetylene reduction activity and microbial counts were determined after 7 and 30 days of growth. Irrespective of the soil type Azotobacter spp. were commonly isolated under maize cultivation. Inoculation of agricultural soils with a suspension of A. chroococcum led to an increase in Azotobacter numbers, although this effect diminished with time. Nitrogenase activity was detected on maize roots and increased in response to the inoculation with A. chroococcum, showing that this associative growth could be of primary importance for the plant. The results of assays for acetylene reduction activity indicated that the nitrogenase activity was associated only with the root systems.     

Effects of soil compaction and arbuscular mycorrhiza on corn (Zea mays L.) nutrient uptake

Soil compaction is of great importance, due to its adverse effects on plant growth and the environment. Mechanical methods to control soil compaction may not be economically and environmentally friendly. Hence, we designed experiments to test the hypothesis that use of plant symbiotic fungi, arbuscular mycorrhiza (AM) may alleviate the stressful effects of soil compaction on corn (Zea mays L.) growth through enhancing nutrient uptake. AM continuously interact with other soil microorganisms and its original diversity may also be important in determining the ability of the fungi to cope with the stresses. Hence, the objectives were: (1) to determine the effects of soil compaction on corn nutrient uptake in unsterilized (S1) and sterilized (S2) soils, and (2) to determine if inoculation of corn with different species of AM with different origins can enhance corn nutrient uptake in a compacted soil. Using 2 kg weights, soils (from the field topsoil) of 10 kg pots were compacted at three and four levels (C1, C2, C3 and C4) (C1 = non-compacted control) in the first and second experiment, respectively. Corn (cv. 704) seeds were planted in each pot and were inoculated with different AM treatments including control (M1), Iranian Glomus mosseae (M2), Iranian G. etunicatum (M3), and Canadian G. mosseae, received from GINCO (Glomales In Vitro Collection), Canada (M4). Corn leaf nutrient uptake of N, P, K, Fe, Mn, Zn and Cu were determined. Higher levels of compaction reduced corn nutrient uptake, however different species of AM and soil sterilization significantly increased it. The highest increase in nutrient uptake was related to P (60%) and Fe (58%) due to treatment M4S2C3. Although it seems that M3 and M4 may be the most effective species on corn nutrient uptake in a compacted soil, M2 increased nutrient uptake under conditions (C3 and C4 in unsterilized soil) where the other species did not. Through increasing nutrient uptake AM can alleviate the stressful effects of soil compaction on corn growth.