不同行距对乌苏1号无芒雀麦产籽量的影响

不同行距对乌苏1号无芒雀麦产籽量的影响试验结果表明,乌苏1号无芒雀麦种子生产以行距60cm条播为最佳播种行距,为大面积推广应用提供了科学依据。     

69份无芒雀麦种质资源遗传多样性分析

利用ISSR分子标记技术鉴定来自国内外69份无芒雀麦材料的种质遗传多样性。19个ISSR引物共扩增出109条谱带,其中104条是多态条带,多态性位点比率为95.41%。用POPEGEN32软件对数据进行分析,结果表明,69份无芒雀麦材料总的Nei’s基因多样性指数为0.255 0,Shannon信息指数为0.396 9,无芒雀麦总的遗传多样性水平较高。用SLT-NTsys2.1e软件对69份无芒雀麦进行UPGMA聚类分析和主成分分析,发现69份无芒雀麦遗传关系复杂,69份无芒雀麦聚类分析在相似系数为0.51处分为8个类群;二维主成分分析将69份无芒雀麦分为9个类群。比较二维、三维主成分分析和UPGMA聚类分析结果,最终将69份无芒雀麦划分成9个遗传类群。     

行距与播种量对无芒雀麦种子产量及产量组分的影响

在酒泉、通辽、绥化3地同时进行了行距与播种量对无芒雀麦种子产量及产量组分影响的试验研究,结果表明:同一地区行距是影响无芒雀麦种子产量的主要因素,播种第2年30 cm行距的种子产量显著高于50 cm,70 cm和90 cm行距处理;播种量对种子产量没有显著影响;3地间种子产量具有显著差异(P<0.05),通辽地区产量最高为1368.4 kg.hm^-2,酒泉次之是1005.2 kg·hm^-2,绥化最低为284.8 kg·hm^-2。行距对无芒雀麦生殖枝数/m2和千粒重影响显著(P<0.05),播种量对无芒雀麦产量组分影响不显著。     

广东省禾本科一新记录属——雀麦属

报道了广东省禾本科一新记录属——雀麦属(Bromus L.)及一新记录种——雀麦(Bromus japonicus Thunb.),标本存放于华南农业大学林学院树木标本室(CANT).     

Dynamics of structural traits in two competing C3 grass species: influence of neighbours and nitrogen

This work analysed the regulatory structural mechanisms involved in the competitive interactions between the annual grass Bromus willdenowii Kunth. (BW = prairie grass) and the perennial C₃ grass Dactylis glomerata L. (DG = orchardgrass) during pasture establishment. Four combinations of species (pure BW, pure DG, DG flanked by BW and BW flanked by DG plants), with and without winter nitrogen fertilization, were factorially arranged in a randomized complete block design. Data were recorded at two organization levels: tillers (three tiller age cohorts) and target plants. Annual neighbours caused a decrease in the number of living leaves in tillers of intermediate age of both species. This structural regulatory mechanism led to a decrease in tiller number per plant and, therefore, restricted the development of horizontal space occupation. Annual neighbours did not cause an increase in tiller size, measured as lamina length or pseudostem height, but decreased root biomass. As a consequence, annual neighbours did not lead the hierarchy in light capture, but limited species radical colonization and competitive ability for soil resources. Winter nitrogen fertilization only affected tiller size in older tillers. These findings emphasize the importance of the cultural decisions, as sowing densities and nitrogen fertilization, to optimize pasture floristic composition.     

Sward herbage accumulation and nutritive value as affected by pasture renovation strategy

Perennial ryegrass pastures are the main feed for dairy cows in temperate regions. Alternatives to increase farm sustainability such as naturalized pastures have been proposed, and only limited knowledge exists regarding their potential as a forage source for grazing dairy systems. A field study was undertaken between September 2006 and September 2009 in Valdivia, Chile, to assess the effect of three pasture renovation strategies [naturalized fertilized (NFP); cultivated fertilized Lolium perenne and Trifolium repens mixture (RGWC); and cultivated fertilized Bromus valdivianus, Dactylis glomerata, Holcus lanatus, Lolium perenne and Trifolium repens mixture (MIXED)] over a naturalized degraded pasture on herbage production, botanical change and chemical composition. The three renovation strategies increased total herbage accumulation. During 2007–2008 and 2008–2009, the naturalized fertilized pasture produced similar amounts of dry matter as the cultivated fertilized mixtures. A higher grazing efficiency (the proportion of total herbage mass accumulation, removed by grazing dairy cows) was estimated for NNFP, RGWC and MIXED. Fertilization and liming increased the proportions of Lolium perenne and Bromus spp. at the expense of Agrostis capillaris and Trifolium repens. In the cultivated mixtures, the amount of Lolium perenne tended to decrease over time. Crude protein concentration and digestibility tended to be higher for naturalized fertilized and perennial ryegrass–white clover pastures throughout the experiment. These results suggest that fertilization and liming of a low-producing naturalized pasture might be a sound alternative for pasture improvement.     

Mycelial growth rate and toxin production in the seed pathogen Pyrenophora semeniperda: resource trade‐offs and temporally varying selection

Pyrenophora semeniperda, an important pathogen in Bromus tectorum seed banks in semi‐arid western North America, exhibits >4‐fold variation in mycelial growth rate. Host seeds exhibit seasonal changes in dormancy that affect the risk of pathogen‐caused mortality. The hypothesis tested is that contrasting seed dormancy phenotypes select for contrasting strategies for increasing pathogen fitness, and that increased fitness on nondormant seeds involves a resource trade‐off between toxin production and growth. The strategy for successfully attacking rapidly germinating nondormant seeds at high inoculum loads in autumn involves increased post‐infection aggressiveness to prevent seed escape through germination. An earlier study demonstrated that slow‐growing strains caused higher mortality than faster‐growing strains on nondormant host seeds at high inoculum loads. In this study, production of the toxin cytochalasin B was significantly higher in slower‐growing strains, and was induced only in seeds or in seed‐constituent‐containing media. Its production was reduced in vivo by Bromus tectorum seeds, suggesting direct involvement in pathogenesis on seeds. Fast‐growing strains caused significantly higher mortality than slow‐growing strains at low inoculum loads on dormant seeds, which apparently have resistance that is overcome at high loads or through rapid mycelial proliferation. In a co‐inoculation study, the fast‐growing isolate produced 3 × more stromata than the slow‐growing isolate on dormant seeds, whereas the slow‐growing isolate was twice as successful on nondormant seeds. These results provide evidence that mycelial growth rate variation and associated variation in cytochalasin B production represent a trade‐off maintained through temporally varying selection resulting from seasonal variation in host seed dormancy status.     

新疆伊犁两种生境无芒雀麦种群的年龄结构

2010年8月,通过单位面积取样的方法,对新疆伊犁草甸和干旱两种生境无芒雀麦（Bromus inermis）自然种群分蘖株、根茎、冬性苗和芽的年龄结构进行了分析,旨在揭示无芒雀麦种群在不同生境条件下的繁殖潜力。结果表明,无芒雀麦种群分蘖株、根茎、冬性苗和芽在两种生境中均以最低的两个龄级占优势。种群生殖分蘖株有3个龄级,营养分蘖株、根茎、冬性苗和芽均有4个龄级;根茎分蘖节最多繁殖4个世代,最多可存活5个生长季。种群的分蘖株数量、芽数量和根茎长度为草甸生境＞干旱生境,冬性苗数量为草甸生境＜干旱生境。营养分蘖株和冬性苗数量为1龄＞2龄＞3龄＞4龄,芽数量为0龄＞1龄＞2龄＞3龄。两种生境下,无芒雀麦种群分蘖株、根茎、冬性苗和芽等构件均呈增长型年龄结构。     

施肥对无芒雀麦种子产量及产量组分的影响

以无芒雀麦为实验材料,经过2年研究观测,结果发现,施氮处理对无芒雀麦种子产量影响显著,秋季施氮135 kg/hm2、春季施氮90 kg/hm2时,种子产量最高达1 723.1 kg/hm2;无芒雀麦种子产量的首要影响因素是单位面积的生殖枝数,生殖枝主要由上年果后短营养枝转化,施氮对单位面积的生殖枝数影响显著,春季施氮增加每生殖枝的小穗数、每小穗的小花数、每小穗的种子数,同时也可以增加当年单位面积的果后短营养枝数;秋季施氮主要增加当年单位面积的果后短营养枝数,使第2年生殖枝数增加,其中秋季施氮135 kg/hm2,生殖枝数最多达728.3枝/m2.     

11份无芒雀麦苗期耐盐性评价

对11份引自俄罗斯的野生无芒雀麦（Bromus inermis Leyss．）材料，在0．3％、0.4％、0．5％NaCl胁迫下，通过存活率、总生物量、叶片伤害率、株高的测定，采用隶属函数法和标准差系数赋予权重法进行耐盐性综合评价。结果表明：供试11份无芒雀麦在0．3％、0．4％、0．5％NaCl胁迫下存活率分别为90％～100％，76．7％～96．7％，67．0％～96．7％；根据耐盐性综合评价值（D）得出供试材料耐盐性顺序为，ZXY04P-371〉ZXY04P-255〉ZXY04P-136〉ZXY04p-188〉ZXY04P-96〉ZXY04P-503〉ZXY04P-34〉ZXY04P-322〉ZXY04P-241〉ZXY04P—46〉ZXY04P-18。