Zn胁迫对黑麦草幼苗生长、生理生化及Zn吸收的影响

采用营养液培养法，研究了不同Zn浓度(0，0.25，0.50，1.00，2.00 mmol/L)对黑麦草幼苗生长、过氧化物酶活性、脯氨酸、根系活力及Zn吸收的影响。结果表明，低锌胁迫对黑麦草幼苗生长无抑制，过度锌胁迫(Zn≥2 mmol/L)将降低黑麦草地上部干质量。幼苗叶内游离脯氨酸含量随锌胁迫时间、锌浓度增加而增加。随Zn胁迫时间增加幼苗POD活性先降后升、根系活力先升后降，锌处理的植株地上部POD活性随锌浓度增加先降低，然后增加，而根系活力随锌浓度增加而增加。黑麦草幼苗地上部和根系Zn含量随Zn浓度的增加而增加，当Zn浓度为2.00 mmol/L时，地上部Zn含量最大值为775.0 mg/kg。     

锌胁迫对重金属富集植物黑麦草养分吸收和锌积累的影响

采用土培根袋试验研究了锌胁迫对重金属富积累植物黑麦草4个品种生长，N、P、K养分及Zn吸收积累的影响。结果表明，Zn在一定范围内（0～520mg／kg）促进了黑麦草生长，RTI（根系耐性指数）≥1.0（0～520mg／kg Zn^2＋）。在Zn^2＋≤260mg／kg（根系）或Zn^2＋≤520mg／kg（地上部）时，黑麦草吸收N、P、K并未受到抑制。植株地上部和根系最大N、P、K含量大多出现在生物量最大或次高的260，520mg／kg Zn^2＋处理中。黑麦草植株Zn含量随Zn胁迫的增加而增加，以泰德植株Zn含量和对Zn的转运率最高（其植株Zn地上部最大含量为583.9mg／kg DW，加Zn处理的S／R〉1）。     

重金属单一污染对龙须草生长与生理生化特性的影响

试验研究了不同处理水平下Cd、Pb、Cu、Zn、As单一污染对龙须草生长和生理生化特性的影响。结果表明:龙须草地下部对重金属的抗性大干地上部,种植龙须草的污染土壤中Cd、Pb、Cu的土壤临界值可分别设定为10mg／kg、300mg／kg和100mg／kg;龙须草叶绿素含量随重金属处理浓度的增加呈先升后降趋势,但其总叶绿素含量和叶绿素a／b值均低于对照;龙须草SOD活性随Zn、As单一污染处理浓度的增加呈先升后降趋势,而随其他3种重金属处理浓度的增加呈下降趋势;龙须草CAT和POD的活性随As处理浓度的增加呈上升趋势,而随其他4种重金属处理浓度的增加呈先升后降趋势。     

水分淋洗下菜园土壤各形态锌的迁移转化特征

采用室内模拟降雨淋溶土柱的方法，研究了经过1年降雨的淋溶后，菜园土壤垂直方向上各形态锌的迁移转化规律。结果表明：锌的大多数形态很难随水分运动发生迁移，～年的降雨至多能使占总量0．57％的水溶态锌发生淋溶损失。水分淋洗和施磷锌平均能使分别占总量3％和4％的难溶态RES—Zn和OX-Zn向易被植物利用的EX—Zn、CABS—Zn和OM—Zn形态转化。随施锌量的增加，土壤锌的有效性指数增加30％～78％．有效锌总量增加3．12～10．07mg／kg。当施磷50mg／kg时，土壤Zn的有效性指数增加3％～28％，有效锌总量增加0．04～0．28mg／kg，磷锌在土壤中表现为协同作用。     

镉对龙葵幼苗生长和生理指标的影响

采用营养液培养法研究了镉胁迫条件下龙葵幼苗生长、生理响应及镉积累特性。结果表明,镉胁迫下,龙葵幼苗生长受到一定程度的抑制,并且具有浓度效应和时间效应。镉胁迫还导致龙葵叶片色素含量下降。叶绿素a、b和类胡萝卜素平均含量在高浓度镉（150μmol·L^-1）处理条件下分别较对照降低55．5％、63．9％和43．3％。低浓度镉（25μmol·L^-1）处理15d内显著促进龙葵幼苗根系活力,平均根系活力较对照上升10．4％,而高浓度镉处理下,根系活力呈现先升后降的趋势,镉处理10d之后达到峰值;随着镉浓度的升高和胁迫时间的延长,龙葵幼苗叶片相对电导率、丙二醛（MDA）含量和渗透调节物质均呈现显著上升趋势。相对于对照植株,低浓度镉处理下龙葵叶片平均相对电导率、MDA含量、可溶性糖和脯氨酸含量上升17．7％、117．7％、5．6％和95．3％,而高浓度镉处理下上升幅度更大,分别为39．0％、194．6％、56．3％和758．0％。从积累部位来看,镉主要积累在龙葵幼苗地上部,镉含量由高到低依次为叶片〉茎〉根系,高浓度镉胁迫20d之后根茎叶镉含量为5d时的1．73、1．49和1．40倍,分别为1287．25、1718．14和2385．27μg·g^-1DW。     

氮肥处理下套作大豆根系建成与产量关系的研究

在小麦／玉米／大豆种植模式中，研究了施氮量对套作大豆（贡选1号）根系性状与产量的效应。结果表明，施氮能增加根干重、一级侧根数和根系活力，提高单株结荚数和百粒重。其中低氮（N45、90kg／hm^2）处理效果较明显，使套作大豆增产16．8％～19．9％；高氮（N180、225kg／hm^2）处理延缓大豆根系衰老，但大豆产量明显较低氮处理低。根系性状与产量之间存在着一定的相关性，在V3（三节期）与R5（始粒期）两个生育时期，所测4个根系参数与产量呈显著正相关，在其它生育时期与产量的相关性较差。     

AM真菌和水分条件对稀土尾矿堆中植物生长的影响

通过温室盆栽试验研究了不同水分处理下接种3种丛枝菌根（AM）真菌（Diversispora spurcum、Glomus aggre gatum和Glomus constrictum）后对稀土矿砂中黑麦草（Lolium perenneL.）和狗牙根（Cynodon dactylon（L.）Pers.）植物株高、地上和地下部分干重及植株内Pb和Zn含量的影响。结果表明：不同水分处理下黑麦草和狗牙根与AM真菌均有一定的结合。在干旱胁迫（W1和W2）下,接种3种AM真菌均提高了黑麦草的株高、地上和地下部分干重,其中,接种Glomus aggregatum促进作用最为显著,重度干旱胁迫（W1）处理下接种后黑麦草株高、地上和地下部分干重比对照分别提高了76.16%、202.86%和481.82%;接种Glomus constrictum显著提高了狗牙根的株高、地上和地下部分干重,W1处理下狗牙根接种后的株高、地上和地下部分干重比对照分别提高了119.17%、290.63%和247.37%。接种AM真菌的植株内Pb和Zn含量与AM真菌种类、植物品种、水分处理及重金属性质等相关,在W1处理下接种Glomus constrictum显著降低了黑麦草植株内Pb的含量,而对Zn的含量影响不大;而对于狗牙根,在W1处理下接种Glomus constrictum显著增加了其Pb和Zn的含量。此外,还测定了植物叶片丙二醛和脯氨酸含量,结果显示接种AM真菌明显降低了干旱处理下黑麦草和狗牙根叶片丙二醛和脯氨酸含量,表明接种AM真菌能有效提高植物的抗逆性。     

铜锌复合胁迫对芦竹生理生化特性、重金属富集和土壤酶活性的影响

以芦竹为供试植物,通过盆栽试验研究在铜、锌复合胁迫下,芦竹生理生化特性的变化,对铜锌吸收积累的规律和4种土壤酶活性的影响。结果表明,在较低复合浓度Cu2+为100mg/kg,Zn2+为100mg/kg时,芦竹植株开始出现伤害症状;随铜、锌复合浓度的增大,叶片中叶绿素含量不断下降,CAT和SOD活性先上升后下降,POD活性持续下降,MDA和脯氨酸含量及细胞质膜透性均随铜锌复合浓度的增加而上升;根部是重金属累积的主要部位,芦竹中重金属铜、锌含量的分布规律均为根(地下部分)茎、叶(地上部分),根和地上部分的Cu、Zn累积浓度随着Cu、Zn添加浓度的升高不断上升;低浓度Cu2+为100mg/kg,Zn2+为100mg/kg对土壤中蔗糖酶的活性有一定的促进作用,当复合浓度达到Cu2+为200mg/kg,Zn2+为200mg/kg后,蔗糖酶的活性随复合浓度的上升呈下降趋势,其余3种酶的活性始终随复合浓度的升高而降低。研究表明,芦竹对铜锌复合污染土壤具有一定耐受力。     

低温胁迫对嫁接黄瓜生理生化特性的影响

研究了嫁接黄瓜在人工低温胁迫条件下的耐冷性。结果表明：嫁接苗发生冷害的时间迟于自根苗，并且受害程度较轻；嫁接苗的电解质渗出率低于自根苗；在低温胁迫初期嫁接苗游离脯氨酸含量均高于自根苗，随胁迫时间延长，自根苗游离脯氨酸含量高于嫁接苗，嫁接苗的根系活力较自极苗高２１．３％。     

4种草本植物对酸性黄壤中铅的吸收特性研究

研究4种草本植物（黑麦草、狗牙根、早熟禾、翦股颖）对重金属铅的吸收积累规律,为生态环境建设提供科学依据。采用盆栽试验,分别测定地上部与根部铅含量,计算地上部铅含量/根系铅含量（S/R）,根系耐性指数,富集系数4个指标。4种植物地上部和根系中的铅含量与土壤中铅含量呈显著的正相关,相关系数都大于0.90;综合4个指标,对铅的抗性相对顺序为翦股颖〉黑麦草〉早熟禾〉狗牙根。在较高铅离子浓度处理下,4种植物外观没有表现出明显的胁迫现象,特别是黑麦草和翦股颖在重金属Pb含量高达3000 mg/kg的污染土壤上,能够忍耐并正常生长,更适合于Pb污染土壤的修复。     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

Einfluss der düngungsmethoden auf die entwicklung von zuckerrübenkrankheiten

Während neunjähriger (1994-2002) Untersuchungen in der Versuchsanstalt Ba?cyny (Fahlerde, Fall-Gleyboden, ausgebildet aus leichtem Lehmboden) wurde der Befall mit Krankheiten an der Zuckerrübe in Abhängigkeit von der Düngungsmethode bewertet. Folgende Methoden wurden angewendet: A - Mineraldünger, B - Stalldung und Mineraldünger, C - Stroh-, Gründung und Mineraldünger, D - Kompostdünger und Biopräparate (ökologische Düngung). Auf den Objekten A, B, C wurden bei konstanter Phosphor-Kalium-Düngung die Stickstoffgaben von 0 bis 180 kg.ha^?1 differenziert. Auf dem ökologischen Objekt D ohne Mineraldünger wurden statt Stickstoff die Biopräparate P₅₀₀ und P₅₀₁ verabreicht. Der geringste Befall von Krankheiten wurde an der Zuckerrübe auf jenem Objekt festgestellt, das mit Kompost und den Biopräparaten gedüngt worden war. Im Rahmen der konventionellen Düngungsmethoden wurde allgemein die höchste Intensität der Krankheiten an der mit Stroh, Gründung und Mineraldünger gedüngten Zuckerrübe beobachtet. Ausnahmen von dieser Regel bildete das Vorkommen von echtem Mehltau und Keimlingsfäule. Auf den Objekten A, B, C nahm die Intensität der Krankheiten mit der Steigerung der Stickstoffgabe zu. Auch die auf Objekt D verabreichten Biopräparate stimulierten die Entwicklung der Krankheiten. The effect of various fertilization methods on the diseases of sugar beet was estimated on the basis of nine-year studies (1994-2002) conducted in the Experimental Production Farm in Ba?cyny on loess-based, sedimentary-gley, light-clay soil. The following fertilization methods were applied: A - mineral fertilization, B - mineral and manure fertilization, C - straw, green manure and mineral fertilization, D - ecological compost and biodynamic preparations fertilization. In the objects A, B and C fertilized with phosphorus and potassium, various doses of nitrogen ranging from 0 to 180 kg/ha^?1 were used. In the ecological object D, where mineral fertilization was not used, biodynamic preparations P₅₀₀ and P₅₀₁ were applied instead of nitrogen. The lowest ratio of the diseases of sugar beet was observed in the object fertilized with the compost and biodynamic preparations. In view of the conventional fertilization methods, generally the highest incidence of diseases was noted in the sugar beet fertilized with straw, green manure and mineral fertilizers. The exception was the occurrence of powdery mildew and the black leg. In objects A, B and C the incidence of the diseases increased with the increase in nitrogen doses. The applied biodynamical preparations in the object D stimulated the development of diseases too.     

Prospects for control of Pythium damping-off of lettuce with Trichoderma,Gliocladium and Enterobacter spp.

Summary Damping-off of lettuce (Lactuca sativa) caused by Pythium ultimum was studied in pots containing a non-sterile potting mix in the glasshouse. Fifty P. ultimum sporangia g^-1 compost reduced the plant stand to 15% and shoot dry weight to 18%, but this reduction was totally prevented by applying Trichoderma harzianum at 2×10⁵ viable propagules g^-1 potting mix. Gliocladium virens and Enterobacter cloacae also alleviated the damping-off. E. cloacae did not adversely affect the action of the fungal antagonists. The co-existence of the bacterial and fungal antagonists was revealed on the root surface and inner surface of the testa by scanning electron microscopy, indicating the compatibility of the biocontrol agents.     

细菌、真菌及植物氮营养信号研究进展

氮素吸收代谢是所有生物生命活动的核心部分,因此,各种生物对氮的吸收与同化过程都有精细的调节。这种调节依赖于生物对体内氮素状况信号及体外（生长介质中）氮素信号的感受。过去几十年中,在细菌、真菌中已经对氮素营养信号有了较好的研究,而植物中则相对缓慢,但也有了一定的认识。本文重点比较细菌、真菌及植物中氮信号系统的组成,以期为进一步认识植物中的氮信号接受与转导系统提供启示。     

Aircraft operations near concentrations of birds in Antarctica: The development of practical guidelines

Aircraft operations have the potential to disturb and to impact negatively on bird life. A gradient of increasing behavioural response is evident in birds when exposed to increasing aircraft stimulus. The most major disturbance is likely to lead to impacts on the health, breeding performance and survival of individual birds, and perhaps bird colonies. A process of revision to policies on aircraft operations contained in management plans for a number of specially protected areas in Antarctica by the United Kingdom, accompanied by consultations made within the scientific community through the Scientific Committee on Antarctic Research (SCAR) and with operational interests through the Council of Managers of National Antarctic Programmes (COMNAP) resulted in new guidelines being adopted by the Antarctic Treaty Consultative Parties in June 2004. The principal recommendations of the guidelines are that bird colonies should not be overflown below 2000 ft (∼610 m) above ground level and landings within 1/2 nautical mile (∼930 m) of bird colonies should be avoided wherever possible. These guidelines are less stringent and less specific than those that were recommended by the SCAR specialist group on birds, and represent a compromise to accommodate operational needs. While the adoption of clear and consistent guidelines for the operation of aircraft in Antarctica is welcome in that this provides practical advice that is likely to reduce incidences of close aircraft/bird encounters, there remains insufficient knowledge of the interactions between aircraft and birds in Antarctica, and the consequent impacts on individual birds and on bird populations. It is important, therefore, that the guidelines adopted are considered interim, and should be kept under scrutiny with revisions made as new and improved research results appear.     

The abundance of heterocystous blue-green algae in rice soils and inocula used for application in rice fields

Summary Algal populations were quantified (as colony-forming units [CFU] per square centimetre) in 102 samples of rice soils from the Philippines, India, Malaysia and Portugal, and in 22 samples of soil-based inocula from four countries. Heterocystous blue-green algae (BGA) were present in all samples. Nostoc was the dominant genus in most samples, followed by Anabaena and Calothrix. In soils, heterocystous BGA occurred at densities ranging from 1.0 × 10² to 8.0 × 10⁶ CFU/cm² (median 6.4 × 10⁴) and comprised, on average, 9% of the total CFU of algae. Their abundance was positively correlated with the pH and the available P content of the soils. In soil-based inocula, heterocystous BGA occurred at densities ranging from 4.6 × 10⁴ to 2.8 × 10⁷ CFU/g dw (dry weight), comprising only a moderate fraction (average 13%) of the total algae. In most soils, the density of indigenous N₂-fixing BGA was usually higher than that attained by applying recommended rates of soil-based inoculum. Whereas research on the practical utilization of BGA has been mostly directed towards inoculation with foreign strains, our results suggest that attention should also be given to agricultural practices that enhance the growth of indigenous strains already adapted to local environmental conditions.Maître de Recherches ORSTOM (France), Visiting Scientist at IRRI