Freezing Stress Influences Emergence of Germinated Perennial Grass Seeds

In sagebrush rangelands perennial bunchgrasses are typically seeded in fall and a high proportion of planted seeds germinate prior to winter onset but fail to emerge in spring. Our objectives were to evaluate freezing tolerance of germinated but nonemergent bluebunch wheatgrass seeds under laboratory conditions. We used data from a 2-yr pilot study to determine overwinter freezing temperature and duration for soils in southeastern Oregon. We then conducted two experiments to assess freezing tolerance. In experiment 1, bluebunch wheatgrass seeds were planted in control pots and compared to seeds planted at early, mid, or late postgermination stages. Pots from each treatment were placed in a grow room maintained at 12 h 40 min light/11 h 20 min dark photoperiod, with a constant temperature of 22°C for 30 d either immediately or following a 30-d freeze. In experiment 2, germinated bluebunch wheatgrass seeds were planted in pots that were left nonfrozen or were frozen for a specified duration prior to a 30-d period in the grow room. Emergence density and tillers · seedling^?1 were quantified for both experiments. The number of days per year for freezing soil conditions in the pilot study ranged yearly from 25 to 51; maximum duration of continuous freezing was 16.5 and 11.2 d. Freezing reduced or eliminated seedling emergence at all postgermination stages (P < 0.001) and tiller density was reduced by at least 50% (P < 0.001). Maximum reduction in seedling density (P < 0.001) was realized within 4 d of initiation of freezing and tillers · seedling^?1 were reduced 30–70% with > 6 d of freezing (P = 0.001). Our data indicate that freezing-associated mortality of germinated but nonemergent bluebunch wheatgrass seedlings can be extremely high and suggest that management practices to reduce prewinter germination of seeds could improve subsequent emergence and seeding success.     

Increasing Shrub Use by Livestock in a World with Less Grass

Much of the world's rangeland is dominated by woody species. Competing land uses and continued encroachment of woody species into non–woody-dominated rangelands have reduced grasslands in many parts of the world. Land use conversions to fuel and feed global populations, especially the increasing number of middle class people seeking broader, meat-based diets, will certainly continue. Halting and/or reversing further encroachment of woody species into grasslands is slow, expensive, and in some cases not possible. Yet, global livestock numbers continue to increase to meet the growing demand for red meat and other livestock products. How do we reconcile a world with less grass and the concurrent increased demand for forages to feed livestock? Strategies and mechanisms are needed to safely enhance shrub use by ruminants in order to capitalize on a presently underutilized forage resource. A number of approaches are presently available (e.g., choosing appropriate species and breeds, providing dietary supplements and additives, behavior modification, genetic selection) to increase shrub consumption, and new technologies such as biochemical markers of shrub intake need to continue to be identified and developed. Such strategies could provide important means for rural communities to adapt to changing land cover and climate.     

三种预处理方法对多年生王草的酶解产糖效果研究

以高产多年生牧草王草为材料,比较常温稀碱法、微波辅助稀碱法、超声辅助稀碱法三种预处理方法对王草的酶解产糖效果的影响。结果表明:常温稀碱法处理的条件为NaOH浓度3%(w/v),固液比1∶15(w/v),处理时间36h,王草的酶解还原糖产量是406.98mg/g,超声辅助法糖产量最高可比常温稀碱法提高24.65%,微波辅助法最高可提高17.95%。最优的预处理方法为超声辅助稀碱法1,还原糖产量为507.31mg/g。     

石羊河流域浅山干旱区牧草引种试验

为选择适合石羊河流域干旱地区种植的牧草,对9个多年生禾本科牧草进行了物候期、产草量和适应性研究。结果表明：老芒麦、肥披碱草、垂穗披碱草、冰草和西伯利亚冰草在产草量和适应性方面表现较好,适宜在该地区推广种植,可以作为退耕还草、建立人工草地的优质牧草。     

高寒牧区初建多年生禾草人工草地杂草群落特性的研究

对高寒牧区人工多年生禾草草地建植第一年杂草群落特性进行的研究结果表明 ,该区禾草人工草地杂草种类组成较为简单 (13种均为阔叶杂草 ) ,但危害很大 ,其中灰绿藜、萼果香薷、微孔草等不但生长旺盛 ,与禾草共生同期生长 ,且密度和盖度大 ,频度高 ,为该草地群落的优势杂草种。通过计算SDR4 值 ,该人工草地群落为 :灰绿藜 -萼果香薷 -禾草 ,即杂草为主的群落 ,故必须进行杂草的防除 ,否则人工草地建植失败。此外 ,通过分析还提出了杂草防除建议     

祁连山区建植二年不同人工草地杂草群落特性的研究

对祁连山区人工多年生不同禾草草地建植第二年杂草群落特性进行的研究结果表明,该区禾草人工草地杂草种类组成较为复杂(26种均为阔叶杂草),但危害不大,只是其中细叶亚菊生长旺盛,与禾草共生,同期生长,频度较高,密度、盖度较小。通过计算SDR4值知该草地杂草入侵不严重。     

农杆菌介导多年生黑麦草遗传转化体系的建立

AVP1基因能够提高植物的抗盐性,通过农杆菌介导AVP1基因转化多年生黑麦草,并建立了较为成熟的遗传转化体系。研究表明,将预培养4d的黑麦草胚性愈伤组织经OD600为0.6左右的农杆菌菌液在负压下侵染6min,共培养3d,用250mg/L的羧苄青霉素(Carb)脱菌,附加150μmol/L的乙酰丁香酮(AS),然后转接到含75mg/L潮霉素(Hpt)的筛选培养基上进行筛选培养的转化体系效果最佳。     

高寒地区微肥对多年生人工草地生产性能的影响

在5a中华羊茅（Festuca china）和冷地早熟禾（Poa alpigena）人工草地上，进行不同微量元素肥料配比的追肥试验。试验结果表明：（1）在中华羊茅和冷地早熟禾处理组中，进行的硼砂、硫酸铜和硫酸锌的追肥处理，对牧草的地上生物量和种子产量有提高作用。在中华羊茅草地里，硼肥处理分别提高地上生物量和种子产量为12．2％和10．2％；在冷地早熟禾草地里分别提高13．2％和10．2％，差异均显著；但Cu肥、Zn肥处理组间的差异不显著；（2）硼肥对中华羊茅和冷地早熟禾两种植株的分蘖密度和有效小穗数影响显著，分别提高12．3％、9．3％、10．5％和8．8％；铜肥和锌肥效果的差异不显著。     

高寒地区微肥对多年生人工草地生产性能的影响

在5a中华羊茅(Festuca china)和冷地早熟禾(Poa alpigena)人工草地上,进行不同微量元素肥料配比的追肥试验。试验结果表明:(1)在中华羊茅和冷地早熟禾处理组中,进行的硼砂、硫酸铜和硫酸锌的追肥处理,对牧草的地上生物量和种子产量有提高作用。在中华羊茅草地里,硼肥处理分别提高地上生物量和种子产量为12.2%和10.2%;在冷地早熟禾草地里分别提高13.2%和10.2%,差异均显著;但Cu肥、Zn肥处理组间的差异不显著;(2)硼肥对中华羊茅和冷地早熟禾两种植株的分蘖密度和有效小穗数影响显著,分别提高12.3%、9.3%、10.5%和8.8%;铜肥和锌肥效果的差异不显著。     

Establishment and Trends in Persistence of Selected Perennial Cool-Season Grasses in Western United States

Restoring western US rangelands from a site dominated by invasive annuals, such as cheatgrass and medusahead, to a diverse, healthy, perennial plant ? dominated ecosystem can be difficult with native grasses. This study describes the establishment and trends in persistence (plant/m²) of native grass cultivars and germplasm compared with typically used crested and Siberian wheatgrasses at four locations in Idaho (one), Wyoming (one), and Utah (two) that range in mean average annual precipitation (MAP) from 290 to 415 mm. Sites were cultivated and fallowed 1 yr before planting using two glyphosate applications to control weeds. We monitored seedling establishment of 10 perennial cool-season grass species and plant persistence over 5 yr. Precipitation during the seeding year varied with the Utah sites locations reviving below MAP (4% and 14%), while the Wyoming and Idaho sites received above MAP at 8% and 26%, respectively. Across these four sites, native grass seedling establishment of bottlebrush squirreltail (29 ± 0.08 [standard error] seedling/m²), bluebunch (28 ± 0.05), slender (30 ± 0.05), and Snake River wheatgrasses (28 ± 0.08) was similar to “Vavilov II” Siberian wheatgrass (36 ± 3.20). By yr 5, western, Snake River, and thickspike wheatgrasses were the only native grasses to have plant densities similar to Vavilov II (37 ± 0.29) Siberian and “Hycrest II” (36 ± 0.29) crested wheatgrasses. On sites receiving between 290 and 415 mm MAP, our data suggest that native grasses are able to establish but in general lack the ability to persist except for western, Snake River, and thickspike wheatgrasses, which had plant densities similar to crested and Siberian wheatgrasses after 5 yr.     

Chitosan Influences the Expression of P-gp and Metabolism of Norfloxacin in Grass Carp

The aim of this study was to investigate the relationship between the administration of chitosan (CTS), expression of permeability glycoprotein (P-gp), and the metabolism of norfloxacin (NOR) in Grass Carp Ctenopharyngodon idella. Fish were administrated with a single dose of either NOR, CTS, 1:5 NOR–CTS or 1:10 NOR–CTS. The P-gp expression was analyzed by immunohistochemistry and real time-PCR. The concentration of NOR was determined using HPLC. The mRNA and protein expression of P-gp in the fish intestine was significantly enhanced following a single dosage of 40 mg/kg NOR, and peak expression occurred at 3 h after drug administration (P < 0.05). A single dosage of both 1:5 NOR–CTS and 1:10 NOR–CTS reduced the intestinal P-gp expression to levels significantly lower than that from NOR alone (P < 0.05), but significantly higher than that from the control (P < 0.05). Interestingly, CTS alone also led to a slight decrease in P-gp expression. In addition, pharmacokinetic assays revealed a marked increase in area under the curve (AUC) of NOR with 1:5 and 1:10 NOR–CTS, by approximately 1.5-fold and threefold, respectively. Finally, the relative bioavailability of NOR after a single oral dosage of 1:5 and 1:10 NOR–CTS was enhanced to 148.02% and 304.98%, respectively. In this study, we demonstrated that the transmembrane glycoprotein P-gp regulates NOR metabolism in the intestine of Grass Carp, suggesting that NOR may be a direct substrate of P-gp. More importantly, we showed that CTS can inhibit P-gp expression in a dose-dependent manner and improve the relative bioavailability of NOR in this species.

Received August 25, 2014; accepted November 12, 2014     

松嫩平原十五种多年生禾草种群营养繁殖体冬眠特性的分析

通过对典型群落多点随机取样的调查与观测，对松嫩平原１５种天然多年生禾草种群营养繁殖体的冬眠特征进行定量分析。其中，羊草、星星草、朝鲜碱茅、硬拂子茅、拂子茅、假苇拂子茅、光稃茅香、野大麦、肥披碱草、硬质早熟禾１０种禾草是以莲座丛和不定芽两种形式冬眠。糙隐子草、芦苇、牛鞭草、白草、白茅５种禾草仅以不定芽形式冬眠。在春季的种群结构中两种形式冬眠的１０种禾草均以冬性植株占绝对比率，达９０．１１％±９．９６％。１０种禾草冬性植株的越冬率高达９４．６８％±５．２６％。羊草种群的生殖株中冬性植株比率达９４．０９％±５．３８％，星星草、朝鲜碱茅、野大麦、光稃茅香、硬质早熟禾５种禾草种群的生殖株１００％为冬性植株。     

Enriched Topographic Microsites for Improved Native Grass and Forb Establishment in Reclamation

Low seed germination and seedling establishment are the greatest challenges for revegetation success. Topographic microsites are known to enhance seed germination and seedling establishment due to their unique soil properties and provision of shelter from elements and herbivores; soil amendments can supply organic matter and nutrients for plant establishment and growth when limited. We investigated the effect of three topographic microsites and six soil amendments and their additive effects on three disturbed grasslands in central and southern Alberta, Canada. Treatments were topographic microsites of mounds, pits, and flats, with and without amendments (erosion control blanket, hay, straw, manure, hydrogel, control) and were seeded with four native grasses and three native forb species. Seedling emergence and survival and soil temperature and water content were assessed over two seasons and plant cover over three seasons. The effect of microsites and amendments was not additive. The addition of erosion control blanket, hay, and straw to flat sites was just as productive as on topographic microsites. These amendments increased grass and forb emergence and buffered soil temperature. Mounds increased first year forb emergence and reduced over winter survival rates for grasses and forbs. Pits were not beneficial for revegetation. The effect of topographic microsites and amendments was influenced by site conditions.     

Reproductive Effort and Seed Establishment in Grazed Tussock Grass Populations of Patagonia

The importance of sexual reproduction in tussock grasses that regenerate through vegetative growth is unclear. Festuca gracillima Hook. f. was studied as a model because it is a perennial tussock-forming grass that produces abundant seed but rarely regenerates through seedlings. The Study area was the Magellanic Steppe, Patagonia, Argentina (182 mm rainfall), managed with sheep-grazing regimes of 0.65 (high), 0.21 (low), and 0 (exclosure) ewe equivalents · ha^?1 · yr^?1. Tussock size and spikelet production of 358 individuals were recorded over 5 yr. Yearly models of reproductive effort in relation to plant size were tested using a maximum likelihood procedure. Seed was collected and soil cores were tested for germination and viability. Survival and growth of cohorts of seedlings sown in nylon bags were recorded. Eighteen experimental plots were cleared, and seed establishment under protected and grazed conditions was registered. Reproductive effort varied with years and plant size, with a mean of 2.41%. Florets were produced at mean density of 544 ± 217 · m^?2. Predispersal losses reduced viable seed production to 187 ± 48 seeds · m^?2. Seed weighed 2–2.5 mg, with 65–95% germination. Postdispersal losses reduced the seed bank in spring to 33 ± 1.3 seeds · m^?2. Seedling survival curves were negatively exponential, with 95% mortality in the first year. Up to 5% of resources were used for sexual reproduction in favorable years and a recruitment of 1–3 new seedlings · m^?2 · yr^?1 was expected. These new plants were not observed in undisturbed plots, but established naturally in cleared plots and reached a density of 1 plant · m^?2 after 10 yr, together with 44 plants · m^?2 of other species. Competition might block the final establishment in these grasslands. Grazing does not appear to interfere in any stage of seed reproduction. Seed production may not maintain population numbers but could enhance genetic variation in these clonal plant populations and enable dispersal and recolonization of disturbed areas.     

猪舍废弃垫料对2种草坪草生长与耐旱性的影响

为开发利用猪舍废弃垫料使其成为无土草皮基质,试验以猪舍废弃垫料为原料,以体积比配制基质,设置6个处理:T1:90％纯沙+10％废弃垫料;T2:70％纯沙+30％废弃垫料;T3:50％纯沙+50％废弃垫料;T4:30％纯沙+70％废弃垫料;T5:10％纯沙+90％废弃垫料;T6:100％废弃垫料;以大田土壤为对照,以高羊茅(Festuca arundinace)和多年生黑麦草(Lolium perenne)为试验草种,研究废弃垫料对草坪草生长和抗旱性的影响.结果表明:添加废弃垫料的各基质,草坪草叶宽、叶绿素含量和可溶性蛋白均明显高于对照;废弃垫料明显促进草坪草生长,其在基质中所占比例越高,草坪草生长态势越好;废弃垫料中含有的重金属并未对草坪草产生毒害.抗旱试验表明,废弃垫料较大田土壤具有较高的持水能力和营养元素含量,在同等干旱水平下能维持草坪草正常生理代谢,缓解干旱胁迫对草坪草的影响.     

几种冷季型草种直播建坪和营养体建坪方法的比较研究

以８种冷季型草种为材料对２种建坪方法从盖度、成坪时间、成坪质量及坪用性状等方面进行综合比较,结果表明：营养体建坪能明显提高草坪盖度,增加草坪草种苗地上和地下生物量,缩短成坪时间,直播建坪成坪时间慢,但成坪质量高。通常情况下２种方法依待建草坪类型而采用。