Cytogenetic identification of Aegilops squarrosa chromosome additions in durum wheat

Summary A set of four normal chromosomes (1D, 2D, 3D, and 6D), and three translocation chromosomes (4DS·5DS, 5DL·7DS, and 7DL·4DL) involving all 14 chromosome arms of the D-genome were obtained as monosomic additions from Aegilops squarrosa (genome D, n=7) in Triticum durum Desf. cv PBW114 (genome AB, n=14). The cyclical translocation occurred during the synthesis of the amphiploid probably as a result of misdivision and reunion of the univalents during meiosis of the F₁ hybrid T. durum x A. Squarrosa. The amphiploid was backcrossed twice with the durum parent to obtain monosomic addition lines. The monosomic addition chromosomes were identified by C-banding and associated phenotypic traits. All monosomic addition lines were fertile. The development of disomic and ditelosomic addition lines is underway, which will be useful for cytogenetic analysis of individual D-genome chromosomes in the background of T. Durum.Contribution No. 90-117-J from the Wheat Genetics Resource Center and Kansas Agricultural Experiment Station, Kansas State University, Manhattan     

氮磷添加对内蒙古温带典型草原净氮矿化的影响

氮素矿化是决定土壤供氮能力的重要生态过程, 也是目前国内外土壤氮循环研究的重点。养分添加在调节土壤的氮转化方面起着重要的作用。该文以内蒙古锡林河流域温带典型草原为研究对象, 通过不同水平的氮(N)和磷(P)养分添加实验, 利用树脂芯原位培养法分析研究不同水平施氮、施磷对生长季草地土壤氮矿化的影响。结果表明: 高氮处理对草地土壤硝态氮(NO₃^- -N)、铵态氮(NH₄⁺ -N)及无机氮都有明显的影响, 其中25 g N·m^?2·a^?1和10 g N·m^?2·a^?1高氮处理显著提高了无机氮含量, 25 g N·m^?2·a^?1高氮处理显著增加土壤的NO₃^- -N及NH₄⁺ -N含量。与施氮相比, 施磷处理对土壤NO₃^--N、NH₄⁺ -N及无机氮的影响较为有限, 只有12.5 g P₂O₅·m^-2·a^-1的磷处理显著促进了NO₃^- -N及无机氮含量。高氮处理对草地土壤氮素转化有明显影响, 其中25 g N·m^?2·a^?1高氮处理对净硝化速率、氨化速率及矿化速率都有显著的促进作用, 说明高梯度的施氮处理有利于提高土壤的供氮能力。氮是内蒙古锡林河流域草原生态系统有机氮矿化的限制因子。与施氮相比, 施磷处理对草地土壤氮转化的作用较为有限, 仅有12.5 g P₂O₅·m^-2·a^-1 + 2 g N·m^?2·a^?1处理显著促进生长季中期的净氨化速率。说明施磷对土壤氮转化的影响弱于施氮的影响。养分添加显著提高了草地的地上生物量。 养分添加情景下, 土壤湿度与净矿化速率极显著相关, 表明湿度是影响该区域温带草原土壤氮矿化的主效因素。环境因子(如有机碳含量、土壤全氮及土壤C/N)与不同氮处理下的净矿化速率之间显著相关, 而土壤微生物碳、氮含量与土壤氮矿化均没有显著相关性。     

Effects of resource additions on species richness and ANPP in an alpine meadow community

Aims Theories based on resource additions indicate that plant species richness is mainly determined by the number of limiting resources. However, the individual effects of various limiting resources on species richness and aboveground net primary productivity (ANPP) are less well understood. Here, we analyzed potential linkages between additions of limiting resources, species loss and ANPP increase and further explored the underlying mechanisms.Methods Resources (N, P, K and water) were added in a completely randomized block design to alpine meadow plots in the Qinghai-Tibetan Plateau. Plant aboveground biomass, species composition, mean plant height and light availability were measured in each plot. Regression and analysis of variance were used to analyze the responses of these measures to the different resource-addition treatments.Important findings Species richness decreased with increasing number of added limiting resources, suggesting that plant diversity was apparently determined by the number of limiting resources. Nitrogen was the most important limiting resource affecting species richness, whereas P and K alone had negligible effects. The largest reduction in species richness occurred when all three elements were added in combination. Water played a different role compared with the other limiting resources. Species richness increased when water was added to the treatments with N and P or with N, P and K. The decreases in species richness after resource additions were paralleled by increases in ANPP and decreases in light penetration into the plant canopy, suggesting that increased light competition was responsible for the negative effects of resource additions on plant species richness.     

A hybrid material flow analysis for quantifying multilevel anthropogenic resources

This study develops a hybrid material flow analysis (HMFA) method to evaluate the annual additional quantity of material stock, known as net additions to stock (NAS) at both micro‐ and macro‐levels through analyzing the fixed capital formation (FCF) and total supply in input‐output tables (IOTs). HMFA turns NAS from a balance indicator in the top‐down approach to an indicator with meaningful value in terms of urban ore evaluation. To verify the validity of HMFA, this study compares the developed HMFA with a top‐down approach and a bottom‐up approach through assessing the NAS of Taiwan and Germany. The quantity of NAS estimated by HMFA is considered as a more conservative upper bound than that by the top‐down approach, while underestimation often occurs with a bottom‐up approach. HMFA has been proven as an efficient and rational evaluation method which overcomes a key limitation in assessing micro‐level material stock by a top‐down approach, and solves the data demanding problem of the bottom‐up approach for quantifying material stock.     

亚高寒草甸植物群落种多度分布关系及相似性对氮磷添加的响应

以青藏高原亚高寒草甸为研究对象,采用随机区组设计,通过连续4a添加N、P,研究了不同施肥(N、P、N+P)处理下群落物种丰富度、种多度分布模式以及群落相似性的变化特征。结果显示:(1)N、N+P连续添加4年后,随N素添加水平的增加,草地植物群落物种丰富度逐渐降低(P0.001);种多度分布曲线的斜率逐渐增大;N+P添加处理对植物群落物种丰富度和种多度分布(SAD)曲线的影响较单独N添加处理更显著,如N15P15处理下群落物种丰富度的降幅最大,达对照群落的65.5%;(2)单一N或N+P处理中,不同添加量间的植被组成趋异,而相同添加量的植被组成趋同(stress level=0.152);(3)N、N+P添加引起刷状根的丛生型禾本科植物逐渐在植物群落中占据优势;(4)P素添加对群落物种丰富度、种多度分布曲线、群落相似性和不同生长型组成及比例的影响不显著;(5)植物生长型特征和N/P添加处理可解释56.97%植物群落的物种多度分布特征。这些结果表明:亚高寒草甸地区N添加引起植物群落组成的重新排序、优势种的变化、SAD曲线逐渐陡峭,群落的相似性增加;N富集时,添加P素会增加N素的利用效率,且群落结构受N、P供应水平的影响。     

空气NH3增高情况下不同形式氮源对荫香光合作用和氮利用的影响

 生长在供给NO-3 N、NH+4 N和NH4NO3 N氮源下的荫香（Cinnamomum burmanni）幼树暴露在增高空气NH3浓度下30 d。利用气体交换测定和氮分析研究了植株的光合作用、氮利用和氮在光合过程一些组分中的分配,根据Farquhar-von Caemmerer模式得出相关光合参数。结果表明在增高空气NH3下生长于NO-3 N的植株Rubisco最大羧化速率（Vcmax）和最大光合电子传递速率（Jmax）较正常空气下的高,但生长于NH+4 N和NH4NO3 N的植株则较正常空气下的低。无论生长于何种形式氮下的植株,在空气NH3增高下以单位叶面积为基准的叶氮含量（Na）显著增高（p<0.05）。在增高空气NH3下,生长于NO-3 N下的植株,其类囊体氮量（NT）、Rubisco氮（NR）和结合于光合电子传递链的氮（NE）的含量较正常空气下的增高（p<0.05）;而生长于NH+4 N和NH4NO3 N下的植株则较正常空气下的低。表明在空气NH3增高下生长于NO－3 N的植株能有效地利用氮合成光合过程必要的组份,而生长于NH+4 N和NH4NO－3 N的植株氮在NT、NR和NE的分配受到部分限制。在空气NH3增高下生长于NO－3 N和NH4NO3 N的植株,其以单位干重为基准的有机氮量较正常空气下的高,但生长于NH+4 N的植株则较正常空气下的低,此外在空气NH3增高下生长于NO－3 N的植株的可溶性蛋白氮较正常空气下增高,而生长在NH+4 N的植株亦见降低。结果表明空气NH3增高可能有利于NO－3 N下生长的荫香植株利用空气中的氮,促进叶片光合速率提高,而空气NH3增高能抑制NH+4 N或NH4NO3 N下生长的荫香植株光合作用和氮的利用和再分配。