Grassland Research Institute Research Articles

重度放牧对欧亚温带草原东缘生态样带土壤氮矿化及其温度敏感性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 重度放牧对欧亚温带草原东缘生态样带土壤氮矿化及其温度敏感性的影响 DOI: 10.5846/stxb201810082172 作者: 作者单位: 中国农业科学院草原研究所,中国农业科学院草原研究所,中国农业科学院草原研究所,中国农业科学院草原研究所,中国农业科学院草原研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点基础研究发展计划（973计划）项目（2014CB138806）；国家重点研发计划政府间国际科技创新合作重点专项（2016YFE0116400）；中央级公益性科研院所基本科研业务费专项（1610332016013） Effects of heavy grazing on soil nitrogen mineralization and temperature sensitivity along the Eastern Eurasia Steppe Transect Author: Affiliation: Grassland Research Institute，Chinese Academy of Agricultural Sciences,Grassland Research Institute，Chinese Academy of Agricultural Sciences,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以欧亚温带草原东缘生态样带为平台，以样带上未放牧和重度放牧配对样地为研究对象，开展重度放牧对欧亚温带典型草原土壤氮矿化及其温度敏感性的影响研究。结果表明：（1）在室内培养条件下，土壤氮积累量和土壤净氮矿化速率呈现出干燥度指数较大的样点显著大于干燥度指数最低的样点（P < 0.05）。在相对湿润的样点，土壤氮素矿化周转速率较快；（2）重度放牧对不同样点土壤氮积累量和土壤氮矿化速率的影响是不同的。在干燥度指数较高样点，重度放牧样地土壤铵态氮减少量和速率较未放牧样地低（P < 0.05），重度放牧显著降低了土壤硝态氮积累量、无机氮积累量、硝化速率、净氮矿化速率（P < 0.05）；在干燥度指数较低样点，重度放牧样地土壤铵态氮减少量和速率较未放牧样地高（P < 0.05），重度放牧对土壤硝态氮积累量、无机氮积累量、硝化速率、净氮矿化速率影响不大（P > 0.05）；（3）土壤氮矿化作用温度敏感性（Q10）变化范围在1.61-2.06，重度放牧对Q10无显著影响。随着纬度的升高，Q10呈升高趋势。Q10与基质质量指数以及表观活化能与基质质量指数均呈显著的负相关关系（P < 0.05）；（4）土壤硝态氮积累量、无机氮积累量、硝化速率、净氮矿化速率对重度放牧的响应比与干燥度指数呈极显著负相关（P < 0.01），重度放牧对欧亚温带典型草原土壤氮矿化的影响受气候条件（温度和降水）的调控。 Abstract:Effects of heavy grazing on soil nitrogen mineralization and temperature sensitivity in the Eastern Eurasian Steppe were studied using laboratory incubation methods by comparing non-grazing plots with heavy grazing plots at different sites. The results showed that accumulations of soil nitrogen and soil nitrogen mineralization rates were significantly higher in sites with a higher aridity index (AI) than sites with a lower AI (P < 0.05), which indicated that soil nitrogen turnover rates were high in relatively humid sites. In sites with a higher AI, the amount and rate of soil ammonium nitrogen reduction in heavy grazing plots were lower than that of non-grazing plots (P < 0.05), and heavy grazing significantly decreased accumulations of soil nitrate nitrogen (Anit), accumulations of soil inorganic nitrogen (Amin), soil nitrification rate (Rnit), and net nitrogen mineralization rate (Rmin) (P < 0.05). In sites with lower AI, the amount and rate of soil ammonium nitrogen reduction in heavy grazing plots were higher than that of non-grazing plots (P < 0.05), and heavy grazing had little effect on Anit, Amin, Rnit, and Rmin (P>0.05). The temperature sensitivity of net nitrogen mineralization (Q10) ranged from 1.61 to 2.06 and heavy grazing had little effect on Q10. Q10increased with increasing latitude and showed a significant negative correlation with the substrate quality index (P < 0.05). There was a significant negative correlation between substrate quality index and apparent activation energy (P < 0.05). Furthermore, the response ratios of Anit, Amin, Rnit, and Rmin to heavy grazing were significantly negatively correlated with AI (P < 0.01). Our results emphasized that the effects of heavy grazing on soil nitrogen mineralization in the Eastern Eurasian Steppe was regulated by climate (temperature and precipitation). 参考文献 相似文献 引证文献

不同放牧强度季节调控下荒漠草原主要植物种群点格局及空间关联性

PDF HTML阅读 XML下载 导出引用 引用提醒 不同放牧强度季节调控下荒漠草原主要植物种群点格局及空间关联性 DOI: 10.5846/stxb201509171915 作者: 作者单位: 中国农业科学院草原研究所,内蒙古农业大学,中国农业科学院草原研究所,中国农业科学院草原研究所,中国农业科学院草原研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点基础研究发展计划（973计划）（2014CB1388022）；科技部“十三五”农村领域国家科技计划项目（2012BAD13B00）；中国农业科学院科技创新工程（CAASASTIP-IGR） Point pattern and spatial association of primary plant populations in the seasonal regulation of grazing intensity in desert grassland Author: Affiliation: Grassland Research Institute, CAAS,Inner Mongolia Agricultural University,Grassland Research Institute, CAAS,Grassland Research Institute, CAAS,Grassland Research Institute, CAAS Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:种群空间格局是种群自身特性、种间相互关系及环境条件综合作用的结果。以短花针茅荒漠草原为研究对象，运用Programita软件，采用Ripley's K函数和Monte Carlo随机模拟方法，对短花针茅、无芒影子草和碱韭种群点格局及空间关联性进行了研究。结果表明：短花针茅在禁牧和过度放牧下集群分布的尺度在增加，禁牧和过度放牧两种草地利用方式下短花针茅种群的格局具有趋同的趋势；并且，随着放牧强度的增大或者是持续放牧的影响，使得随机分布尺度在逐渐的增大，短花针茅在更大的尺度上才可能为集群分布。春季重牧+夏季重牧+秋季轻牧和全年重度放牧利用下无芒隐子草在较大尺度上才表现为集群分布，并且尺度转化的临界点在放牧的影响下有增大的趋势；重度放牧下碱韭为了适应放牧干扰逐渐向集群分布方向发展，集群分布的尺度在减小以提高种群的稳定性从而抵御过度的干扰。在不同的放牧干扰强度下植物种群具有明显的响应策略，大致表现为物种的群居性在增强，物种集群分布的尺度在减小以提高种群的稳定性从而抵御过度的干扰。春季休牧+夏季重牧+秋季轻牧处理下种群斑块化的尺度较大，有利于群落的稳定，因此荒漠草原采用这种利用方法较为合理。 Abstract:The spatial distribution pattern of a population demonstrates a combination of the unique characteristics of the population, and the interrelationship between species and the environment. In the present study, Stipa breviflora was used to examine the point pattern and spatial correlation of primary plant populations using Programita software, Ripley's K function, and the Monte Carlo Method. The results showed that the scale of random distribution gradually increased with elevation of grazing intensity, or continuous grazing, and may be the primary explanation for the clustered distribution of populations at large scales. The clustered distribution scale of S. breviflora increased in the "grazing prohibited" and "overgrazed conditions". These two conditions were also associated with a convergence trend in S. breviflora. Increasing grazing intensity, or continuous grazing, gradually amplified the random clustered distribution scale of S. breviflora and may be the primary explanation for this clustered distribution. On a larger scale, Cleistogenes songorica showed a clustered distribution under "heavy grazing in spring+heavy grazing in summer+light grazing in autumn", and "heavy annual grazing". The critical point of the above scale conversion showed an increasing trend with grazing. Allium polyrhizum showed a trend of clustered distribution in response to grazing disturbance. The clustered distribution of this species was reduced to improve the population stability and avoid interference. Plant populations had specific response strategies under different grazing intensities, including enhancement of species sociality, and reduction of the clustered distribution, to improve population stability and avoid excessive disturbance. S. breviflora, C. songorica, and A. polyrhizum had either no correlation or a negative correlation at the small scale. At larger scales, primary plant species had either no correlation or a positive correlation. At a scale of 0-250 cm,S. breviflora and A. polyrhizum showed no correlation in conditions of "heavy grazing in spring+heavy grazing in summer+light grazing in autumn". However, at larger scales, S. breviflora and A. polyrhizum were positively correlated in the conditions of "zero grazing in spring+heavy grazing in summer+light grazing in autumn", and "zero grazing in spring+light grazing in summer+heavy grazing in autumn". Conditions of "spring grazing", "summer grazing", and "fall grazing" produced relatively lager-scale population patches that benefited the stability of the population. Thus, these methods are more suitable for the desert grassland. 参考文献 相似文献 引证文献

Effect of Weed Control on Performance of Guinea Grass-Legumes Intercropping System under Rainfed Conditions

A field experiment was conducted during 2006–2011 on sandy loam soil at Central Research Farm of Indian Grassland and Fodder Research Institute, Jhansi to study the effect of weed control on performance of Guinea grass-legumes intercropping system under rainfed conditions. Intercropping of Stylosanthes hamata with Guinea grass produced significantly higher total dry forage (5.18 t/ha) than Clitoria ternatea (3.89 t/ha), Macroptillium atropurpureum (4.19 t/ha) and S. seabrana (4.67 t/ha) during 1st year of experiment. While during 2nd, 3rd and 4th years, intercropping of Stylosanthes seabrana with Guinea grass produced significantly higher total dry forage yield (9.56, 6.56 and 6.04 t/ha) than Clitoria ternatea (7.92, 5.23 and 4.49 t/ha), Macroptillium atropurpureum (8.12, 5.34 and 4.76 t/ha) and S. hamata (8.76, 5.97 and 5.26 t/ha). In total dry forage yields, per cent contribution of S. seabrana were 34.90, 31.17, 41.62 and 40.73 during 1st, 2nd, 3rd and 4th years respectively. Crude protein yields (812.3, 587.0 and 538.7 kg/ha) were also increased significantly when guinea grass intercropped with S. seabrana than intercropping with C. ternatea, Macroptillium atropurpureum and S. hamata. In weed management practices, hand weeding 35 days after sowing in 1st year and 25 days after onset of monsoon rain from 2nd year onwards recorded significantly higher dry forage yields of both Guinea grass (3.52, 7.81, 4.53 and 4.21 t/ha) and legumes (1.81, 2.48, 2.15 and 1.72 t/ha) than weedy check, pre-emergence application of pendimethalin @ 0.75 kg a.i./ha and weeding with weeder cum mulcher during 1st, 2nd, 3rd and 4th years, respectively. The Maximum net return ( 4232, 20778, 14532 and 15390/ha) and net return per rupee invested ( 0.38, 2.26, 1.64 and 1.63) were obtained by intercropping of Guinea grass with S. seabrana during 1st, 2nd, 3rd and 4th years of study. Hand weeding 35 days after sowing in 1st year and 25 days after onset of monsoon rain from 2nd year onwards also recorded maximum net return ( 3771, 17053, 9796 and 10183/ha) during all the 4 years.

Effect of sward surface height and level of herbage depletion on bite features of cattle grazing Sorghum bicolor swards1

To maximize herbage DMI, pregrazing sward surface height (SSH) and level of herbage depletion (HD) must be such that variables determining short-term herbage intake such as bite mass (BM) and bite rate (BR) are optimized. The objective of this study was to determine a SSH target and the level of HD as a proportion of the SSH that optimizes BM and BR of beef heifers grazing Sorghum bicolor swards. Two experiments were conducted using 2 S. bicolor swards and 4 beef heifers (25 mo old; 322 kg BW). Experiment 1 compared the effect of 6 pregrazing SSH, 30, 40, 50, 60, 70, and 80 cm, on BM, BR, and jaw movements. Experiment 2 assessed the effect of HD level as a proportion of SSH (0.17, 0.34, 0.50, 0.67 and 0.84) on BM, BR, and jaw movements using the optimal pregrazing SSH defined in Exp. 1. Short-term herbage DMI was estimated using a double-weighing technique and corrected for insensible BW loss. Herbage DMI was subsequently used to calculate the BM. Net eating time and jaw movements for apprehension and manipulation + mastication during grazing as well as total jaw movements were determined using the IGER (Institute of Grassland and Environmental Research) behavior recorders. Bite rate and the number of total jaw movements per gram herbage DMI were derived from jaw movement count and measurements of herbage DMI. The results of Exp. 1 showed low and high SSH constraint the ease of herbage harvesting. Greater BM are maintained until a SSH of 50 cm is reached (P < 0.05) and then decline at greater SSH due to herbage dispersion. The nonbiting jaw movement rate increased at greater SSH whereas BR decreased (P < 0.05). For both variables, the turning point was close to a SSH of 50 cm. Experiment 2 showed that such an optimization of BM and BR was maintained until an HD level of 0.34 was reached (P < 0.05). There was a linear increase in both the total jaw movements per unit herbage DMI and the nonbiting jaw movements rate (manipulation + mastication) subsequent to levels of HD greater than 0.34 (P < 0.05). These studies provide, for the first time, sward feature targets to manage grazing and optimize BM and BR, aiming to maximize the short-term herbage DMI of cattle grazing S. bicolor swards.

天山北坡家庭牧场复合系统对极端气候的响应过程

PDF HTML阅读 XML下载 导出引用 引用提醒 天山北坡家庭牧场复合系统对极端气候的响应过程 DOI: 10.5846/stxb201206030804 作者: 作者单位: 中国农业科学院草原研究所;中国农业科学院研究生院;兰州大学草地农业科技学院,中国农业科学院草原研究所,中国农业科学院草原研究所,中国农业科学院草原研究所,中国农业科学院草原研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(70933004;71103185);公益性行业(农业)科研专项(201003019);中央级公益性科研院所基本科研业务费专项资金(1610332012201;1610332012002);内蒙古自然科学基金重大项目(2010ZD08) The response process to extreme climate events of the household compound system in the northern slope of Tianshan Mountain Author: Affiliation: Grassland Research Institute ,Chinese Academy of Agriculture Sciences,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:在草原牧区,家庭牧场作为取代游牧制度而产生的新生事物,其对极端气候响应过程的研究尚未见报道。以"极端气候敏感性-影响途径-响应方式"为分析框架,基于问卷调查方法,研究了天山北坡山地草原牧民对极端气候的响应过程。结果表明:1)天山北坡1980-2009年冬季雪灾、秋季旱灾风险趋于增大,家庭牧场草料储备不足、畜种结构经济驱动型增加了对极端气候的敏感性;2)旱灾、雪灾是影响家庭牧场的主要极端气候类型,其作用介质为牲畜和草场;3)自适应与外力适应是牧户响应极端气候的2种主要形式,其中购买草料是最主要的响应策略;4)通过Probit模型估计显示,极端气候认知、家庭特征、资产状况与牧户间适应行为选择有显著的关系。研究认为,家庭牧场对极端气候短期响应的反馈过程主要围绕草、畜2因子展开,基于降水波动的周期性,牧户长期响应形成了家庭牧场生产周期。 Abstract:The household pasture is a new alternative grazing pattern, replacing nomadic way. The study on the response process of household compound system to extreme climate has not been reported. Taking "extreme climate sensitivity-impact way-response mode" as the analysis framework, the herders' response process to extreme climate is conducted in the northern slope of Tianshan Mountain by means of questionnaire. The results show that: 1) The risk index of winter snowstorm and autumn drought increased with years in 1980-2009. Moreover, the less forage and feed structure driven by market economy make the household pasture more sensitive to extreme climate; 2) Drought and snowstorm are the main extreme climate types which influence households by livestock and pasture; 3) Self-adaption and external adaption are the main response model of herder to extreme climate, and buying forage is the main response strategy; 4) Probit model shows that the herders' adaptive behaviors have significant relationship with extreme climate perception by herders, family characteristics and properties. The results indicate that the short-term response and feedback of household to extreme climate events primarily involved two factors, grass and livestock. In addition, the long-term response of herder to the periodic precipitation fluctuations promotes the formation of production cycle of household pasture. 参考文献 相似文献 引证文献

Seasonal differences in the adaptability of herbage species to environmental variations in a long‐term grazing experiment

AbstractMixtures of orchardgrass, perennial ryegrass, tall fescue, redtop, Kentucky bluegrass, and white clover were sown in autumn 1973. Two 8‐year grazing experiments were conducted at the National Grassland Research Institute (Nasushiobara, Japan) to determine the effects of grazing intensity and nitrogen levels on pasture ecosystems. These experiments involved two different grazing intensities (1974–1981) and two different nitrogen levels (1982–1989). Large spatiotemporal variations in phytomass due to environmental variations were observed in both experiments. Finlay–Wilkinson analysis was applied to clarify seasonal (monthly) differences in the adaptability of the herbage species, as measured by phytomass, to environmental variations by year and treatments in the two experiments. Seasonality in the adaptability to environments differed greatly among species. In this paper, we examined from livestock farmers’ standpoint whether seasonality in adaptability of herbage species in the grazing pasture could be satisfied. A significantly high adaptability was shown for: orchardgrass from May to July and November; tall fescue in April, June and July, and November; redtop and Kentucky bluegrass in April; and Zoysia japonica in September and October. In contrast, perennial ryegrass and white clover exhibited very low adaptability in any season. Z. japonica and weeds such as Pennisetum alopecuroides, Eragrostis ferruginea and Digitaria adscendens, which had invaded from surrounding areas, showed low adaptability, except in autumn, when they showed moderate adaptability.

Processes affecting transfer of sediment and colloids, with associated phosphorus, from intensively farmed grasslands: tracing sediment and organic matter

S. J. Granger,1* R. Bol,2 P. J. Butler,2 P. M. Haygarth,1 P. Naden,3 G. Old,3 P. N. Owens4,5 and B. P. G. Smith3 1 Nutrient Flows and Systems Modelling Team, Institute of Grassland and Environmental Research (IGER), North Wyke Research Station, Okehampton, Devon, EX20 2SB, UK 2 Cross Institute Programme for Sustainable Soil Function (SoilCIP), Institute of Grassland and Environmental Research (IGER), North Wyke Research Station, Okehampton, Devon, EX20 2SB, UK 3 Centre for Ecology and Hydrology (CEH), Wallingford, OX10 8BB, UK 4 National Soil Resources Institute, Cranfield University, North Wyke Research Station, Okehampton, Devon EX20 2SB, UK 5 Environmental Sciences Program, University of Northern British Columbia, Prince George, British Columbia, V2N 4Z9, Canada

사료급원과 급여기간이 Charolais 거세우 근내 지방산 조성에 미치는 영향

본 시험은 n-6 및 n-3 계열 다중불포화지방산 함량이 풍부한 사료원을 Charolais 거세우에게 각각 사료 급여기간을 달리하여 급여하였을 때 근내 지방산 조성을 조사하기 위하여 수행하였다. 시험 수행은 영국 IGER (Institute of Grassland and Environmental Research) 연구소 육우 사양실험실에서 실시 하였으며, 공시축은 총 28두 Charolais 거세우로서 ad libitum으로 조사료 급여를 하였다. 그리고, 두 개의 지방원료원으로서 C18:2 n-6 함량이 풍부한 대두와 C18:3 n-3함량이 풍부한 아마종실을 60일 및 90일간 공급하였으며, 농후사료는 총 건물섭취의 73%으로 하였다. 도체중, conformation 및 fatness score는 60일 사료급여구와 비교하여 90일 사료급여구에서 높게 조사되었다(P<0.05). 공시축의 m. longissimus thoracis의 중성지방내 총지방산 함량은 지방원료원에 의한 영향은 없었지만, 반면에 인지질 내 총지방산 함량은 아마종실 급여구에 대략 15% 높게 나타났다(P<0.05). 근육 중성지방 내 C18:3 n-3와 cis-9, trans-11 CLA 함량은 아마종실급여구에 유의성있게 높게 조사되었으며(P<0.001), 반면에 C18:2 n-6 함량은 대두 급여구에서 높았다 (P<0.001). 근육 인지질 내 CLA와 C18:3 함량은 아마종실급여구에 높게 나타났으며, C18:2 n-6 함량은 대두 급여구에 높았다. 한편, 근육 중성지방 내 C14:0, C16:0, C16:1, CLA, C18:1 n-9, C18:2 n-6 및 C18:3 n-3 함량은 90일 사료급여구에서 높게 조사되었다. 근내 불포화지방산:포화지방산 비율은 사료급여기간에 영향을 받지 않았지만, C18:2 n-6:C18:3 n-3 비율과 n-6:n-3 불포화지방산 비율은 아마종실 급여구에서 높게 나타났다. 따라서 본 시험은 대두 혹은 아마종실 같은 사료급여와 급여기간에 의하여 쇠고기 근내 불포화지방산 함량을 변화 시킬 수 있음을 보여주고 있다. 그리고, 아마종실 급여는 쇠고기 내 지방산 함량이 조성이 인체 건강과 관련한 영양적 지표에 보다 바람직한 것으로 증명되었다. This study investigated the effects of feeding Charolais steers on diets rich in either n-6 or n-3 polyunsaturated fatty acids (PUFA) and time on feed (TOF) on muscle fatty acid composition and content. Twenty eight steers were fed on ad libitum forage and one of two concentrates varying in the source of fat; soya (high in C18:2 n-6) or whole linseed (high in C18:3 n-3) for either 60 or 90 days in IGER (Institute of Grassland and Environmental Research, UK). The concentrates were fed at approximately 0.73 of total DM intake. TOF influenced carcass weight, conformation and fatness scores, which were higher at 90 v. 60 days (P<0.05). Diet did not affect total fatty acid content of neutral lipid in m. longissimus thoracis but feeding linseed increased total phospholipid fatty acid by approx- imately 15%(P<0.05). Linseed increased the amount and proportion of C18:3 n-3 (P<0.001) and the proportion of CLA (cis-9, trans-11 conjugated linoleic acid), while soya increased the content (P<0.05) and proportion (P<0.001) of C18:2 n-6 in muscle neutral lipid. In muscle phospholipid, linseed significantly increased the amount of CLA, C18:3 n-3 and its longer chain derivatives as well as C14:0, C16:0, C18:0. C18:1 trans and C18:2 n-6. The amount and proportion of C18:2 n-6 and its longer chain C20 derivatives were higher on feeding soya. TOF (90 v. 60 day) increased the content of C14:0, C16:0, C16:1, CLA, C18:1 n-9, C18:2 n-6 and C18:3 n-3 in muscle neutral lipid. The P:S was not affected by diet or TOF. The ratio of C18:2 n-6 : C18:3 n-3 and sum of n-6 : n-3 fatty acids were higher in muscle from animals fed on linseed v. soya (P<0.001). The study indicates that the PUFA composition of beef muscle may be significantly modified by feeding contrasting dietary lipids, soya vs. linseed. Feeding linseed produced a better balance of muscle fatty acids, more in line with current nutritional recommendations with a lower C18:2 n-6:C18:3 n-3 ratio associated with higher muscle content of C18:3 n-3 and C20:5 n-3 and CLA and lower C20:4 n-6.

Processes affecting transfer of sediment and colloids, with associated phosphorus, from intensively farmed grasslands:colloid and sediment characterization methods

Hydrological ProcessesVolume 21, Issue 2 p. 275-279 Invited Commentary Processes affecting transfer of sediment and colloids, with associated phosphorus, from intensively farmed grasslands:colloid and sediment characterization methods L. J. Gimbert, Corresponding Author L. J. Gimbert [email protected] School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, Devon, PL4 8AA, UKSchool of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, Devon, PL4 8AA, UK.===Search for more papers by this authorP. J. Worsfold, P. J. Worsfold School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, Devon, PL4 8AA, UKSearch for more papers by this authorP. M. Haygarth, P. M. Haygarth Cross Institute Programme for Sustainable Soil Function (SoilCIP), Institute of Grassland and Environmental Research (IGER), North Wyke Research Station, Okehampton, Devon, EX20 2SB, UKSearch for more papers by this author L. J. Gimbert, Corresponding Author L. J. Gimbert [email protected] School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, Devon, PL4 8AA, UKSchool of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, Devon, PL4 8AA, UK.===Search for more papers by this authorP. J. Worsfold, P. J. Worsfold School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, Devon, PL4 8AA, UKSearch for more papers by this authorP. M. Haygarth, P. M. Haygarth Cross Institute Programme for Sustainable Soil Function (SoilCIP), Institute of Grassland and Environmental Research (IGER), North Wyke Research Station, Okehampton, Devon, EX20 2SB, UKSearch for more papers by this author First published: 30 December 2006 https://doi.org/10.1002/hyp.6599Citations: 15AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume21, Issue215 January 2007Pages 275-279 RelatedInformation

The effect of temperature and daylength on heading in tetraploid cultivars of rhodesgrass (Chloris gayana Kunth)

AbstractThe present study was conducted to clarify the effect of temperature and daylength on heading in tetraploid cultivars of rhodesgrass (Chloris gayana Kunth). Five cultivars, Tochiraku‐kei (2χ), Fords Katambora (2χ), Callide (4χ), Masaba (4χ) and Pokot (4χ), were planted on three dates at 1‐month intervals (4 May, 4 June and 4 July) in three of the Ministry of Agriculture, Forestry and Fisheries research institutions in Ishigaki (Tropical Agriculture Research Center), Nishigoshi (Kyushu National Agricultural Experiment Station) and Nishinasuno (National Grassland Research Institute) in 1978. Three tetraploid cultivars were planted on three dates at 1‐month intervals (4 May, 4 June and 4 July) under four daylength‐treatments of natural daylength (ND), 12 h daylength [12 h], ND/12 h and 12 h/ND, and changed daylength at the eighth leaf stage, in Nishinasuno in 1978. Under natural daylength, although heading was not observed for Masaba and Pokot, heading was observed in all plots for Tochiraku‐kei, Fords Katambora and Callide, and their days to heading (DH) linearly decreased with increases in daily mean temperature (DMT). The result indicated that, under natural daylength in summer, temperature was a major factor in determining DH in tetraploid Callide, which was the same as in diploid rhodesgrass cultivars. Callide reached heading under all four daylength treatments. However, Masaba and Pokot reached heading only under 12 h and ND/12 h treatments, suggesting that Masaba and Pokot have qualitative sensitivity to photoperiods that operate after the ninth leaf stage. These findings would be useful in tetraploid rhodesgrass for estimating foliage harvesting time in the field and for conducting cross‐pollination in a greenhouse during winter.

Evaluating the adaptability of herbage species to environmental variation through a long‐term grazing experiment

AbstractMixtures of orchard grass, perennial ryegrass, tall fescue, redtop, Kentucky bluegrass and white clover were sown in the autumn of 1973. Two 8‐year grazing experiments were carried out at the National Grassland Research Institute (Nasushiobara, Tochigi, Japan) to determine the effects of grazing intensity and nitrogen levels on the pasture ecosystem: two different grazing intensities (1974–1981) and two different nitrogen levels (1982–1989). Large temporal and spatial variations in phytomass were observed in both experiments. To clarify the adaptability of the phytomass of the herbage species to environmental variations in year, season and treatments, we re‐examined the data obtained in these two experiments using a Finlay‐Wilkinson analysis. Orchard grass and tall fescue achieved significantly higher phytomass in a more fertile environment in that they showed a high adaptability to environmental variation. Redtop and Kentucky bluegrass showed an increase in phytomass proportional to environmental improvement. The phytomass performances of perennial ryegrass and white clover were almost independent of environmental variation in that their adaptability was low. Finally, Zoysia japonica and weeds such as Pennisetum alopecuroides and Digitaria adscendens, which were invaders from the surrounding areas to the experimental site, were not observed in the pasture during the first 8‐year period; during the second 8‐year period, they showed moderate adaptability.

Inter-laboratory variation of in vitro cumulative gas production profiles of feeds using manual and automated methods

A study was conducted to estimate variation among laboratories and between manual and automated techniques of measuring pressure on the resulting gas production profiles (GPP). Eight feeds (molassed sugarbeet feed, grass silage, maize silage, soyabean hulls, maize gluten feed, whole crop wheat silage, wheat, glucose) were milled to pass a 1 mm screen and sent to three laboratories (ADAS Nutritional Sciences Research Unit, UK; Institute of Grassland and Environmental Research (IGER), UK; Wageningen University, The Netherlands). Each laboratory measured GPP over 144 h using standardised procedures with manual pressure transducers (MPT) and automated pressure systems (APS). The APS at ADAS used a pressure transducer and bottles in a shaking water bath, while the APS at Wageningen and IGER used a pressure sensor and bottles held in a stationary rack. Apparent dry matter degradability (ADDM) was estimated at the end of the incubation. GPP were fitted to a modified Michaelis–Menten model assuming a single phase of gas production, and GPP were described in terms of the asymptotic volume of gas produced ( A), the time to half A ( B), the time of maximum gas production rate ( t RM gas ) and maximum gas production rate ( R M gas ). There were effects ( P<0.001) of substrate on all parameters. However, MPT produced more ( P<0.001) gas, but with longer ( P<0.001) B and t RM gas ( P<0.05) and lower ( P<0.001) R M gas compared to APS. There was no difference between apparatus in ADDM estimates. Interactions occurred between substrate and apparatus, substrate and laboratory, and laboratory and apparatus. However, when mean values for MPT were regressed from the individual laboratories, relationships were good (i.e., adjusted R 2 = 0.827 or higher). Good relationships were also observed with APS, although they were weaker than for MPT (i.e., adjusted R 2 = 0.723 or higher). The relationships between mean MPT and mean APS data were also good (i.e., adjusted R 2 = 0.844 or higher). Data suggest that, although laboratory and method of measuring pressure are sources of variation in GPP estimation, it should be possible using appropriate mathematical models to standardise data among laboratories so that data from one laboratory could be extrapolated to others. This would allow development of a database of GPP data from many diverse feeds.

An evaluation of selected perennial ryegrass growth models for development and integration into a pasture management decision support system

Four perennial ryegrass growth models were evaluated for their suitability to form the basis of a herbage growth model (HGM) for a decision support system (DSS). The successful candidate had to be suitable for further development to meet the specification of the DSS and following redevelopment it would then be integrated into a pasture management decision support system for dairy production. The models selected for evaluation were the Irish produced Brereton model (Brereton et al. 1996), the LINGRA model (Schapendonk et al. 1998), produced in the Netherlands, and a version of the English Johnson &amp; Thornley (1985) model, developed for field use at the Northern Ireland Plant Testing Station (Laidlaw &amp; Gilliland 2000). The fourth model was a version of the LINGRA model, simplistically adapted by the authors to take account of reproductive growth (LINGRARep). The performance of the models was tested using the mean squared prediction error (MSPE) against a total of 28 seasons' growth data, collected from two sites; i.e. at the former Grassland Research Institute at Hurley, England and the Northern Ireland Plant Testing Station at Crossnacreevy. The Brereton model, when validated against the Hurley dataset, had the lowest MSPE of the four models, but had the highest MSPE against Crossnacreevy data. The PTS model did not perform as well as expected considering its mechanistic basis. Equally, the performance of the LINGRA model was poor at both sites. However, the LINGRARep performed well, having the lowest MSPE at Crossnacreevy and second lowest at Hurley. The LINGRA model was selected for development as the final HGM given that it proved suitable for adaptation and by making even simple adaptations, as in LINGRARep, its performance could be substantially improved. Therefore, it was considered that it possessed the greatest potential for further development.

Using Leaf-mark Material to Monitor the Morphology of White Clover ( Trifolium repens L.) at the Clone and Ramet Level in Grazed Swards

Leaf markings are widespread in Trifolium spp. White clover ( T. repens L.) material has been produced at the Institute of Grassland and Environmental Research (IGER) Aberystwyth, UK, which demonstrates the ‘filled - V’ leaf mark as a subtle but clearly identifiable mark with little seasonal variation in expression. This paper describes how a population of genotypically identical individual white clover plants (clones), created from this material, can be used in grazed swards to monitor changes in morphology at the clone and ramet level. In a pilot experiment, the effect of a late silage cut on the white clover component of grazed mixed swards was investigated. Leaf-mark plants were introduced into known positions in a grass/clover sward in 1997 and monitored during 1998 under two grazing regimes: (1) continuous grazing to a sward surface height of 4 cm (treatment G); and (2) grazing, followed by a single late-season silage cut, a brief rest period, and a return to autumn sheep grazing (treatment GRG). The GRG treatment had a significant and rapid effect, producing larger clones with a larger number of ramets and higher proportions of complex ramets than the G treatment. As ramet complexity increased the treatment effect intensified, resulting in a four-fold increase in clone size, together with an enhanced ability to spread into the sward. The GRG treatment allowed a more widespread dispersal of individual units and this is likely to enhance the opportunity for ramets to encounter favourable micro-environments for survival and growth. The benefits and limitations of the procedures are discussed.

Calendin, tyrosol and two benzoic acid derivatives from Veronica persica (Scrophulariaceae).

Veronica persica Poiret (Family: Scrophulariaceae), the `Common Field Speedwella or `Persian speedwella, is a neophytic weed originally from south-west Asia and widely distributed in the temperate regions (USDA-ARS GRIN database, 1999; Fischer, 1987; Holm et al., 1979). The plants were garden weeds and collected in #ower near Aberystwyth (Tyn-y-Graig, Wales), and a voucher specimen (N9623) of this collection has been retained in the herbarium at the Institute of Grassland and Environmental Research (IGER) also known as WPBS, Aberystwyth, Wales.

Roles of plant biomass and vegetational heterogeneity, and energy-matter cycling in grassland sustainability

A long-term survey of energy, carbon and nitrogen budgets in a grassland has been carried out since 1974 at the National Grassland Research Institute, Japan. Based on the survey, a system model describing energy and matter flows was constructed. Sustainability of grassland ecosystems in relation to productivity was evaluated by simulations. The results indicated that at low and high levels of animal productivity the grassland ecosystems were able to accumulate carbon in soil year by year, and there was no appreciable indication of decrease in the nitrogen content in soil provided that a given amount of fertilizer was applied to the grassland. The heterogeneity in plant biomass can be described by a gamma distribution. Grasslands grazed by domestic animals such as cattle and sheep display a strong spatial heterogeneity. This characteristic is caused by the uneven deposition of excreta by grazing animals, uneven use of the grassland by grazing animals, and uneven dispersal of plant seeds by grazing animals over the grassland. It was suggested that such unevenness may accelerate energy and matter cycling, and then contribute to grassland sustainability.

The effect of cutting and intensive grazing managements on sward components of contrasting ryegrass and white clover types when grown in mixtures

A field experiment was established at the Institute of Grassland and Environmental Research (IGER), Aberystwyth, to compare the seasonal growth and annual yields of two white clovers when grown with each of five perennial ryegrasses. Swards were subjected to two contrasting defoliation managements, namely cutting only and continuous grazing with sheep. In addition to data recorded on dry matter yields of the swards, the effect of management on growth and development of white clover stolons and tillering of ryegrasses was also studied in the third harvest year. The management of the swards had a significant effect on ryegrass tiller number and on the ingress of weed grasses. Differences in persistency and tillering among the ryegrasses were significantly greater when continuously grazed by sheep than when swards were cut. It is argued that ingress of weed grasses under grazing could be used as an indicator of ryegrass persistency. Among those studied, only two of the ryegrasses were able to provide dense persistent swards under continuous sheep grazing. The white clovers included in this experiment differed in leaf size with Gwenda smaller than Ac 3785. Greater differences existed between white clover components when grazed than when under cutting management. Under continuous sheep grazing there were large differences between the clover varieties in stolon length, stolon weight, number of growing points and root weight.The data indicate the importance of the persistence of mixture components under continuous sheep grazing and, since ryegrass is the main component of a clover/grass seed mixture, greater emphasis in breeding and evaluation programmes should be given to persistence, especially under grazing.

Peduncle characteristics, inflorescence survival and reproductive growth of white clover (Trifolium repens L.)

AbstractField experiments were carried out in four harvest years to compare the peduncle characteristics and reproductive growth of the small‐leaved white clover (Trifolium repens L.) cv. AberDale, selected for long and strong peduncles, with other varieties bred in the Institute of Grassland and Environmental Research (IGER). The peduncles of cv. AberDale were of larger diameter and had a greater fresh and dry weight than those of other varieties. There were also differences in structure as the peduncles of cv. AberDale had more pronounced ridges and furrows than those of cv, Menna.Inflorescences of cv. AberDale and other varieties were tagged when in full bloom throughout the flowering period in each of the four harvest years. Generally, more inflorescences of cv. AberDale remained intact until harvest, particularly from the early tagging dates. Although there were seasonal differences, at harvest in each of the 4 years, cv. AberDale had more inflorescences and seeds per floret and a greater potential seed yield than the other varieties.The basis of peduncle strength and effect on reproductive growth is discussed, and the implications for improving the seed yield potential of white clover varieties is considered.

Nitrogen Economy, Seed Production Efficiency and Seed Vigour of Panicum maximum by Intercropping of Pasture Legumes

A field experiment was conducted to evaluate the performance of pasture legumes (Desmanthus virgatus, Sesbania aegyptica, Macroptelmm autropurpureum, Desmodium tortuosum, Stylosanthes hamata used as in intercropped element) in terms of nitrogen economy, seed production efficiency and seed vigour potential of Panicum maximum– a grass based management maintained for 1986–88 at Research Farm, Indian Grassland and Fodder Research Institute, Jhansi under rainfed condition. Nitrogen economy under these intercropped pasture legumes was estimated on equating its value against nitrogen treatment i.e. 0, 10, 20, 30 and 40 kg N/ha. Among five intercropped legumes, Stylosanthes hamata and Macroptelium autropurpureum intercropping doubled the seed yield; S. aegyptica and M. autropurpureum brought out 46–55 per cent increase in biomass production over control value of 41.7 kg seed and 223.4 q biomass/ha respectively. These treatment showed 20–40 kg N/ha nitrogen equivalent value. Further more increased seed yield of Panicum maximum under intercropping was attributed to its better ear production, spike length and potential sink strength. Germination potential of harvested Panicum seeds under different treatments did not show variation among themselves. Potential seed production performance of Panicum maximum in the first year as compared to subsequent years might be due to its general transcript of plants and have some interaction with rainfall.

Grassland utilisation in england and wales 1984–5 and 1985–6

Animal performance from grassland is dependant both on the grass growth achieved and the efficiency of utilisation. The Grassland Research Institute and ADAS conducted a series of trials (GM 20) which showed grass growth to be mainly influenced by the available water capacity of the soil, summer rainfall and altitude. This gives a site class which together with the fertilizer used determines the quantity of herbage grown.Less is known of the variation in utilisation of the grass grown. This analysis has been undertaken to assess the levels of grassland utilisation found on dairy farms of England and Wales.