黄土丘陵沟壑区不同草本植物生长期植物纤维毯对沟道边坡产流产沙的影响

为探究植物纤维毯在黄土丘陵沟壑区的适用性以及不同植物生长期植物纤维毯的水土保持效益,以内蒙古呼和浩特市清水河县为研究区,采用野外人工模拟降雨试验方法,对植物生长期为58,81,132天的直播草本边坡和植物纤维毯边坡径流产沙进行模拟试验。结果表明:(1)植物纤维毯护坡措施可显著延长边坡产流时间,并且产流时间随着植物生长期的增加而增加。在植物生长期为58,81,132天时,植物纤维毯边坡产流时间分别为86,110,243 s,明显大于裸坡(50,70,111 s)和直播草本边坡(73,83,123 s)。(2)随着植物生长期的增加,植物纤维毯边坡径流量从13 125 mL降至5 478 mL,产沙量从73 g降至22 g;直播草本边坡径流量从25 573 mL降至14 340 mL,产沙量从201 g降至82 g。(3)植物纤维毯护坡措施减流效益为55%～78%,减沙效益为71%～89%。(4)坡面植被高度、盖度是植被生长状况中影响径流产沙的主要因子,径流量、产沙量与植被高度和盖度呈多元线性函数关系。植物纤维毯能够有效降低黄土丘陵沟壑区沟道边坡土壤侵蚀,减少产流。     

植被护坡研究进展与展望

在回顾国内外植被护坡发展简史的基础上,总结了植被护坡的功能,详细介绍了植被护坡机理的研究进展。从植物的截留降水、削弱溅蚀和抑制地表径流等方面分析了植被护坡的水文效应,并从植物单根抗拉强度、根-土相互作用、根-土复合体及边坡稳定分析等方面分析了植物护坡的力学效应,最后探讨了植被护坡的发展方向。     

城市河渠生态护坡技术效益对比——以北京市新开渠为例

在城市河渠整治工程的边坡防护中,已初步使用生态防护方式,但各种边坡防护措施的防护效果差异明显.应科学地采用生态边坡防护措施或生态与工程相结合的防护措施,使河道坡面稳定以实现生态治理的目的.通过建立边坡绿化试验小区,选择液体喷播、铺设生态植被毯、三维植被网等生态护坡技术,对各自的经济、生态效果进行分析,并对各类生态护坡技术进行评价.结果表明,铺设生态植被毯是一项经济可行、防护效果理想的技术措施.     

生态型框技术在护坡工程中的抗侵蚀效应研究

试验研究了一种生态护坡技术——生态型框护坡的抗侵蚀效应。试验表明,生态型框护坡的抗侵蚀效应明显优于人工撒草护坡技术,随着植被覆盖度的提高,生长的植物根系起到了固土保土作用,对于减少土壤流失量有着较好的效果。     

青藏高原东北地区边坡恢复技术探讨

近年来高寒地区生态环境问题备受关注,青藏高原特殊的地理位置和气候条件,使其不仅影响周围区域的生态安全,还威胁到全国的生态安全。在介绍青藏高原东北地区不同的边坡类型,以及讨论边坡喷播技术、边坡水泥抹面技术、植生带护坡技术、生态草毯护坡技术、植被混凝土边坡防护技术的基础上,通过实地调研,对比分析得出,无土生态草毯护坡技术和植被混凝土边坡防护技术可以在气候环境比较恶劣的青藏高原东北地区快捷、有效地修复各类边坡。     

水库消落带消浪植生型生态护坡技术应用

以消浪固土为生态护坡目标,通过设计一种自锁定消浪植生型生态护坡构件,最大限度地降低波浪冲刷力,保护消落带表层土壤,并在构件植物栽植孔中种植牛鞭草、狗牙根、野地瓜等水土保持植物,在水陆交界面形成一个连续的波浪缓冲带,同时有效发挥植物根系的固土护坡作用,从而实现生物—工程相结合的消落带坡面防护。该技术具有稳定性高、适应性强、消浪作用好以及环境友好的特点,可显著减轻波浪对消落带坡面的侵蚀作用,提高植被保存率。     

三种生态护坡形式的水土保持效果研究

选取北京市昌平区朱辛庄水土保持示范基地内的4个径流小区为研究对象,其中3个分别进行了生态植被毯护坡、椰纤植生毯+客土护坡、六棱花饰砖护坡,1个为空白对照。在2015年对4个径流小区的产流和产沙数据进行了监测分析,结果显示:3种生态护坡形式均具有一定的水土保持效果,都能够有效地减少坡面的水土流失;3种生态护坡中椰纤植生毯+客土护坡的保水效果最好,六棱花饰砖护坡的保土效果最好。综合3种生态护坡的产流、产沙数据分析认为,椰纤植生毯+客土护坡的综合水土保持效果要优于其他2种生态护坡形式,可以在研究区附近推广使用。     

森林保持水土涵养水源的效应及评价

森林保持水土、涵养水源的作用层次主要是林冠和林下植被层、枯枝落叶层、根系土壤层,通过这三个层次对降水进行调节,具有截持降水、增加降水入渗、改善土壤性质、吸收和阻延地表径流、抑制土壤蒸发、固土护坡等功能,从而有效避免土壤溅蚀、增强土壤抗冲能力、涵养水源并预防地质灾害的发生。枯枝落叶层是森林保持水土的重要力量。完整的森林系统不会加重水土流失。在干旱的季节或年份,森林会加重土壤干旱的说法缺乏科学依据。     

湿喷植被混凝土生态护坡技术在水渠边坡工程中的应用

[目的]验证湿喷植被混凝土生态护坡技术的先进性与实用性,为工程边坡生态防护提供参考。[方法]将湿喷植被混凝土生态护坡技术应用于湖北省鄂州市花马湖水系连通渠护坡工程,现场观测了护坡和水土保持效果、植物盖度、植株密度、植物平均高度以及物种多样性指标。[结果]湿喷植被混凝土生态护坡技术能促使边坡稳定。所用基材能较好地附着于坡面,未出现冲沟和滑塌,水土保持较好,成功解决了基材可喷射性和坡面附着性之间的根本矛盾;1个月后坡面整体植被覆盖率达到90%以上;缓坡区的Shannon-Wiener多样性指数、Pielou均匀度指数、Simpson优势度指数与陡坡区均较为接近,但与自然边坡存在差异;湿喷综合成本比干喷节约5%～15%。[结论]湿喷植被混凝土生态护坡技术作为干喷植被混凝土生态护坡技术的升级版,具备显著的先进性,能用于工程边坡的生态防护。     

不同降雨强度条件下植被毯护坡技术的产流特性

为了研究不同气候条件下植被毯技术的适用性,分析不同降雨强度条件对径流、入渗系数、入渗深度的影响,设置3种降雨强度(0.56、1.01、2.02 mm/min),通过侵蚀槽填土并布设各类植被毯,模拟施工边坡,并设置无覆盖对照组,使用侧喷式人工降雨大厅对侵蚀槽进行人工模拟降雨试验.结果表明:1)植被毯能够增加径流入渗,在降雨强度为1.01 mm/min时,麦秸秆植被毯和椰丝纤维植被毯最多分别能够增加27.7％和28％的入渗量;2)不同材料植被毯径流过程有明显的差异,在降雨强度为0.50、1.01mm/min时,入渗系数为麦秸秆＞椰丝纤维,降雨强度为2.02 mm/min时,入渗系数为椰丝纤维植＞麦秸秆;3)同种材料不同质量的植被毯径流总量有较大差异,同种材料中,200 ～ 300 g/m2的植被毯在3种降雨强度条件下均能够取得较其他质量植被毯更好的保水效果.     

“绿色革命”以来大气CO2浓度升高对C3作物营养品质的影响

自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications     

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.     

Collection and preliminary evaluation of native turfgrass accessions in Italy

Despite a raising interest on turfs in Italy, all theavailable varieties of this kind in the Country are of foreign origin, and areoften poorly adapted to the prevailing climatic conditions. This prompted tobegin a collection activity of indigenous turfgrass species, with the ultimategoal of identifying promising materials for future breeding based on localgenetic resources. The collection was carried out in three areas of Italy, viz.the northern Po Plain, the coastal region of Liguria, and the island of Sardiniathat are characterised, respectively, by subcontinental, warm temperate, andtypical Mediterranean climate. Altogether, 141 sites were visited, yielding 226accessions belonging to eight species of potential interest for turfs:Poa pratensis, Poa trivialis,Festuca rubra, Festuca arundinacea,Lolium perenne, Agrostis stolonifera,Agrostis tenuis, and Cynodon dactylon,this last being a warm-season grass. Poa pratensis andCynodon dactylon were mostly collected in northern Italyand Sardinia, respectively, whereas Festuca arundinacea andLolium perenne were rather ubiquitous. The collection sitesranged from 0 to 1040 m asl, but sites over 750 m wereonly visited in the inner part of Sardinia. All the accessions, collected aswhole plants, were transplanted at Lodi, northern Italy, where they are beingevaluated. Their preliminary evaluation for traits of importance for turf use,such as sward colour and overall quality, highlighted the great variation andthe occurrence of interesting accessions in all species. Other characters wererecorded, bearing specific importance in individual species, and in all casespromising accessions were identified. The germplasm of Festucarubra, Festuca arundinacea, and Loliumperenne proved highly infected by endophytic (symbiotic) fungi of thegenus Neotyphodium.     

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.     

Leaf position and genotype differences for mineral element concentrations in sorghum grown on tropical acid soil 1

Mineral element deficiencies and toxicities are common problems associated with sorghum [Sorghum bicolor (L.) Moench] production on acid soils. To better understand some of the mineral element problems and the analysis of plant tissue of sorghum plants grown on acid soils, four sorghum genotypes were grown on an acid Oxisol at Carimagua, Colombia limed with dolomite at 2 and 6 Mg ha^‐1.

Samples for mineral element analyses were obtained from leaves at different positions on the four genotypes. Concentrations of P and Mg were highest in the flag leaf (Leaf No. 1) and decreased as the position on the plant declined from the top of the plant for plants grown at 2 Mg lime ha^‐1. Similar decreases in P, Mg, K, and Zn concentrations occurred in plants grown with 6 Mg lime ha^‐1. Concentrations of Ca, S, Si, Mn, Fe, Cu, and Al increased as leaf position declined from the flag leaf for plants grown at 2 and 6 Mg lime ha^‐1. The higher lime supply enhanced Ca and reduced Mn and Fe concentrations in leaves. Differences in mineral element concentrations for the four genotypes used were fairly extensive. The elements to show the greatest range among genotypes were Al and Si and the elements to show the least range among genotypes were P, K, and S. Care should be used in collecting leaf samples for plant analysis and genotypic differences for accumulation of mineral elements should be considered in interpretation of results.