Growth and reproductive performance of beef heifers grazing endophyte-free, endophyte-infected and novel endophyte-infected tall fescue

A three-year study was conducted to investigate the effects of endophyte-free (E−), endophyte-infected (E+) and novel endophyte-infected (EN) tall fescue on the growth and pregnancy rate of beef heifers during the spring. Each year, 48 beef heifers were strip-grazed on stockpiled fescue from December through February, fed fescue hay during late February to early April and then rotationally grazed on spring growth of fescue until June. At the end of the trial, heifers had been maintained on E+, E− or EN (pasture or hay) for a total of 152, 188 and 191 d in years 1, 2, and 3, respectively. In late March, heifers were synchronized using a controlled intravaginal drug-releasing device, (CIDR®) for 7 d followed by injection with PGF2α (Lutalyse®). Heatmount detectors (Kamar®) and observation for behavioral estrus were used to detect estrus for 63 d. Heifers were artificially inseminated 8 to12 h after the onset of standing estrus. Conception was determined by transrectal ultrasonography at approximately 30, 60 and 90 d after synchronization. Reproductive performance did not differ among treatments (P ≥ 0.20). Pregnancy rate was 54, 65, and 65% for E+, E− and EN, respectively. However, during the spring, growth and prolactin were decreased (P < 0.01) for heifers on E+. Gains on spring pasture were 0.24, 0.75, and 0.71 kg/d (SEM ± 0.03) for E+, E− and EN, respectively. Based on these results, the wild type endophyte-infected fescue can be used in production systems as a source of winter forage but producers should consider placing heifers on alternative forage (such as the novel endophyte-infected fescue) in the spring.     

Biogeochemical cycling of carbon and nitrogen in cool-season turfgrass systems

Managed turf areas are both a source and a sink for greenhouse gases (GHGs). Management practices, including turfgrass selection and mowing, influence the amount of carbon (C) and nitrogen (N) stored in the soil, as well as the associated GHG emissions. The objective of this research was to determine the net C and N balance (i.e. the amount of C and N stored less the amount emitted) of managed turfgrass systems with different grasses (species and cultivars) and management practices (mowing frequency and grass clippings management). Data explicitly quantified in this experiment include annual mowing requirements and accompanying GHG emissions, annual dry matter yield, soil C and N accumulation, and GHG flux of tall fescue (Schedonorus arundinaceus) and Kentucky bluegrass (Poa pratensis) cultivars with varying growth rates. Leaf, verdure, and root tissue C and N were also determined, along with the corresponding biomass. Estimations of emissions from fertilization, irrigation, and pesticide applications were also included in the net balance calculations.All of the turfgrasses and management practices in this experiment resulted in a system-wide net C sink, though the magnitude of the sink varied by turfgrass selection and management strategy. In general, higher-yielding grasses and management practices increased soil C but also increased mowing requirements and thus emissions. Returning grass clippings was found to increase yield, soil and leaf tissue N, and soil C, but it also marginally increased mowing requirements. The results of this experiment support the assertion that managed turfgrass areas can act as a net C sink to help curb the increasing atmospheric GHG concentrations. The C sequestration potential of managed turfgrass is another of the numerous functional benefits of urban grasslands.     

多效唑与CaCl2对盆栽高羊茅幼苗生长的影响

本试验分别采用不同浓度组合的多效唑与CaCl2溶液混合喷施处于针叶期生长的高羊茅，研究其对高羊茅幼苗生长以及抗逆性的影响。结果表明：与对照相比，不同浓度的混合处理均显著的抑制了高羊茅幼苗地上部分生长，使叶片变宽，根冠比增加，叶绿素含量增加，幼苗抗旱能力增强。其中以浓度200mg／L的多效唑与浓度0．1％的CaCl2混合剂处理效果最佳。     

高羊茅在中原地区生长特点的研究

高羊茅能够很好地适应中原地区的土壤及气候条件,表现出生长快、叶量丰富、绿期长的特点,地上生物量累积动态呈Logistic曲线,衰减动态符合y=a+blnx规律,峰值在7月,牧草产量为1.07×105 kg DM/hm2。     

修剪对高羊茅生长及草坪质量的影响

研究了不同修剪高度和修剪频率条件下,南京地区高羊茅的生长状况和草坪质量。方差分析表明,低剪（４ｃｍ）的生长量明显高于中剪（６ｖｍ）和高剪（９ｃｍ）,而草坪质量低于高、中剪;高频率修剪（１周２次）的生长量显著高于中频（１周１次）和低频（２周１次）,而草坪质量低于中、低频。因此,在管理上应适当采取高剪（６￣９ｃｍ）和低频（１￣２周１次）,既可以提高草坪质量,又可减轻管理强度。试验结果表明,南京地区高羊     

酶抑制剂对高羊茅代谢菲的影响

[目的]研究了酶抑制剂对高羊茅代谢多环芳烃的影响。[方法]选取不同浓度Vc和Na2SO3处理高羊茅。[结果]高浓度Vc和Na2SO3可以抑制高羊茅对菲的代谢,低浓度时,反而会促进高羊茅对菲的代谢。这可能是由于高浓度酶抑制剂处理中,植物的酶活不会再生,而低浓度酶抑制剂的处理中,植物的酶活会很快再生所致;并且相对于未使用酶抑制剂的对照植物,用低浓度抑制剂处理后,植物酶活会有所提高。[结论]为有效去除多环芳烃,降低其对生态安全和人类健康的危害提供科学依据。     

非土壤基质生产地毯式草皮的成卷研究

本研究选用上海地区工农业生产上的无害废弃物作为基础材料,经科学加工组配成各种非土壤基质生产地毯式草皮卷。研究结果表明,有利成卷的非土壤基质的有机质含量在４０％以上,水解氮、速效磷、速效钾分别在６５０、２３００、９０００ｍｇ／ｋｇ左右,轻质,保水及排水性能均优于土壤,生产相同质量草皮的周期比用传统生产方式缩短１～２个月。     

沙漠乔桑的组织培养与工厂化生产

选取沙漠乔桑不同的外植体,通过芽的诱导、试管苗的快速增殖、试管苗生根和驯化移栽筛选出适宜的工厂化育苗工艺流程。3—6月份选取沙漠乔桑待萌发冬芽、萌发侧芽,流水冲洗干净后,70%酒精浸10s,然后用0.15%氯化汞灭菌5～10min,以不同组合的培养基对外植体进行诱导、快速繁殖、生根。结果表明:以MS BA1.0mg/l(单位下同) NAA0.1作诱导培养基,用MS BA0.5 NAA0.05作增殖培养基进行快速繁殖,以1/2MS NAA0.2作生根培养基,移栽到草炭:珍珠岩:蛭石=3:1:2的混合基质中。通过试验筛选出了一套快速繁殖体系,建立了适宜于沙漠乔桑工厂化生产的工艺流程。     

干旱胁迫下内生真菌对高羊茅保护酶活性的影响

研究对内生真菌 (AcremoniumcoenophialumMorgan Jones&Gams)侵染 (E+)和未侵染 (E- )的交战Ⅱ (CrossfireⅡ )高羊茅 ,在温室持续干旱胁迫下膜系统保护酶活性变化连续测定 ,发现 :在干旱胁迫过程中E+植株的茎、叶中过氧化氢酶 (CAT)的活性均显著高于E- 植株CAT的活性 (P <0 .0 5) ,在茎中的变化差异极显著 (P <0 .0 1)。但E+植株与E- 植株中的过氧化物酶 (POD)的活性表现与CAT活性相反 ,也就是在干旱胁迫过程中E+植株POD酶活性显著低于E- 植株POD活性 (P <0 .0 5)。干旱胁迫下 ,E+植株在抗旱形态特征表现均优于E+植株 ,其根量、卷叶率均高于不带菌植株 ;干旱后的恢复率带菌植株达到 70 %以上 ,而不带菌植株不到 2 %。     

北京地区草坪地草害及其化学防除

通过两年的系统调查，查明北京地区草坪地杂草有６２种，分属２２科，重要杂草在牛筋草（Ｅｌｅｎｓｉｎｅｉｎｄｉｃａ（Ｌ．）Ｇａｅｒｔｎ）狗尾草（Ｓｅｔａｒｉｎｖｉｒｄｉｓ（Ｌ．）Ｂｅａｕｖ）。马唐（Ｄｉｇｉｔａｒｉａｓａｎｇｕｉｎａｌｉｓ（Ｌ．）Ｓｃｏｐ）和旋覆花（ＩｎｕｌａｊａｐｏｕｉｃａＴｈｕｎｂ）。农得时和草克星４０ｇ／亩用量在草坪播后苗前处理对牛筋草，马唐和一年生双子叶草的防效在８５％以下，不