Rehabilitation of the nematode fauna in a phytostabilized,heavily zinc-contaminated,sandy soil

Background Aim and Scope  The Maatheide in Lommel, Belgium, is an extremely metal contaminated, sandy area where vegetation has disappeared over ca. 130 hectares due to the activities of a former pyrometallurgical zinc smelter. To reduce the environmental impact of this area a rehabilitation strategy had to be developed. Therefore, in the centre of this area, an experimental phytostabilization (grass) field of three hectares had been installed in 1990. After a grass cover had been established, the development of the nematode fauna in the phyto-stabilized soil was studied. Nematodes act at various levels in soil ecosystems: herbivorous species extract their food from plant roots, bacterivorous and fungivorous species feed on microbes, predatory species consume other nematodes, and omnivorous species have mixed diets. In a mature soil ecosystem that normally exercises its manifold functions, a diverse nematode fauna occurs, reflecting the intactness of the ecosystem. As such, this fauna is indicative of crop growth, vegetative diversity, organic matter decomposition, microbial activity and diversity, and the maturity of the soil ecosystem. Methods  A metal immobilizing soil amendment (beringite) and municipal waste compost (to improve the nutrient status and water-retaining capacity) were incorporated in the soil and metal tolerant ecotypes of grasses were sown. Soil samples for nematode analyses were taken four times. Results  As a result of the treatment, pH of the soil increased and the water extractable amount of Zn was strongly reduced. Grass growth revitalized the impoverished soil ecosystem, organisms as well as metabolic processes. The nematode fauna of the experimental field in the Maatheide has been studied since 1997 and the recovery of the various feeding guilds and taxa was checked again in 2002. Nematode densities and feeding guilds have normalized, with omnivores and predators as the last guilds to reappear. Up to 27 species with a current diversity were observed in the grass-covered experimental plot, but a number of ubiquitous species, present at a comparable site at some distance, remained absent. Conclusion  It can thus be concluded that rehabilitation of an impoverished soil ecosystem is possible in heavily contaminated soils by means of phytostabilization, but there are some limitations on rehabilitation, since a number of common nematode species remained absent. Further research should indicate if this absence is indicative of a loss of essential processes in the soil. Recommendation and Perspective. Phytostabilization of heavily zinc-contaminated, sandy soil also remediates impoverished soil ecosystems. In particular, the recovery of nematode feeding categories is indicative for the normalization of soil life. The absence/presence of a number of ubiquitous taxa should be checked again after some time to verify if recovery is completed.     

Comparative genome analysis between several tropical grasses

The availability of molecular markers allowed comparing genetic maps between distinct taxa. Among the Poaceae (grasses) family, species as divergent as rice, wheat and maize show collinearity within wide regions along the whole genome. This opens the way for the integration of knowledge across all grasses and the development of molecular tools of general interest using the simple genome of rice. Many agronomically important tropical grasses belong to two major sub-families. Comparisons between maize, sorghum and sugarcane, three members of the Andropogoneae tribe, are briefly reviewed. One example of a particular genome region is used for extending the comparison to rice and illustrating various applications of comparative genome mapping. This revised version was published online in July 2006 with corrections to the Cover Date.     

牧草耐盐力 试验研究

本文对5种禾本科牧草的耐盐力进行了试验研究，出苗期耐盐力为0．3%～0．4%，生长中期为0．5%～0．7%在盐碱地试种表现良好，适宜在黄淮海平原黑龙港缺水盐渍区的中度盐渍土地上栽培。     

Breeding and evaluation of Digitaria eriantha for improved spring yield and seed production

Summary Digitaria eriantha is a subtropical grass which is widely sown as a pasture species in South Africa and cultivars have recently been released in Australia. The species is variable in seed production and in other agronomic attributes. This paper describes a breeding program designed to combine the seed production of cv. Premier with the high productivity in winter-spring of an almost sterile genotype.Hybrids between the two accessions were either triploid and sterile, or diploid with low fertility. The F₂ to F₅ generations were selected intensively for fertility and, at two contrasting sites, for spring productivity, with both maternal and paternal selection. The F₆ generation was grown as replicated swards and yield in spring, and fertility, were used for selection of elite F₅ plants to comprise the parents of a new cultivar (cv. Advance).In evaluation trials, spring dry matter production of Advance averaged 40% higher than that of Premier. On average, seed production of Advance was 11% lower than that of Premier and botanical fertility was consistently about half that of Premier. Experimental yields of cleaned seed of Advance were up to 138 kg/ha. In commerce, seed yields of Advance are likely to be lower than those of Premier unless higher inflorescence densities than Premier can be achieved.     

Saving the sagebrush sea: An ecosystem conservation plan for big sagebrush plant communities

Vegetation change and anthropogenic development are altering ecosystems and decreasing biodiversity. Successful management of ecosystems threatened by multiple stressors requires development of ecosystem conservation plans rather than single species plans. We selected the big sagebrush (Artemisia tridentata Nutt.) ecosystem to demonstrate this approach. The area occupied by the sagebrush ecosystem is declining and becoming increasingly fragmented at an alarming rate because of conifer encroachment, exotic annual grass invasion, and anthropogenic development. This is causing range-wide declines and localized extirpations of sagebrush associated fauna and flora. To develop an ecosystem conservation plan, a synthesis of existing knowledge is needed to prioritize and direct management and research. Based on the synthesis, we concluded that efforts to restore higher elevation conifer-encroached, sagebrush communities were frequently successful, while restoration of exotic annual grass-invaded, lower elevation, sagebrush communities often failed. Overcoming exotic annual grass invasion is challenging and needs additional research to improve the probability of restoration and identify areas where success would be more probable. Management of fire regimes will be paramount to conserving sagebrush communities, as infrequent fires facilitate conifer encroachment and too frequent fires promote exotic annual grasses. Anthropogenic development needs to be mitigated and reduced to protect sagebrush communities and this probably includes more conservation easements and other incentives to landowners to not develop their properties. Threats to the sustainability of sagebrush ecosystem are daunting, but a coordinated ecosystem conservation plan that focuses on applying successful practices and research to overcome limitations to conservation is most likely to yield success.     

Futterqualität und Leistung von Napier-und Paragras (Pennisetum purpureum bzw. Brachiaria mutica) unter Schnittnutzung und Beweidung mit Sahiwal-und Kreuzungsrindern auf "upland" im District Dacca/Bangladesh

Forage quality and performance of Napier and Para grass ( Pennisetum purpureum and Brachiaria mutica , resp.) cut or grazed with Sahiwal and crossed cattle on upland in the Dacca district, Bangladesh
Napier and Para grass were compared with respect to important quality parameters for two years and in a rotational grazing experiment using 30 two-years-old heifers.
Napier grass had a higher in-vitro-digestibility of organic matter (IVDOM) than Para grass. 77% of IVDOM variance was explained by the lignin contents, 88 % by lignin and ash contents. Accordingly a high correlation existed between lignin contents and IVDOM (r =−0.86; p 0,001).
The estimation of starch units resulted in higher precision by including the lignin contents in the regression equations compared with crude fibre contents alone.
Crude protein, crude fibre and magnesium contents were similar, while Napier grass contained substantially more P, K and Ca, but far less Na.
In the grazing experiment on average of both years Napier grass produced 64 % of the plant yield of Para grass, but reached 80 % of the animal production. Of the forage offered by Napier grass and Para grass 85 and 67,5 %, respectively, was converted into animal production. Therefore the weight increase (kg/ha) produced by Napier grass amounted to 90 % of the groups grazing Para grass. Daily gain averaged over both grass species and experimental years reached 440 g/heifer in the Holstein-Friesian group, 410 g with Sahiwal and 370 g with Jersey cattle.     

川中丘陵区农牧结合模式的研究

本文以川中丘陵区的大足县作为研究典型,分析了该县农业生态系统的现状和问题,并提出了以牧草为中心的农牧结合新模式。结果表明,该模式能扭转农业生态系统的恶性循环,促进农、林、牧、副、渔五业的发展。     

四种禾草株高生长进程差异分析

研究四种禾本科草类（冷地早熟禾、星星草、紫羊茅和草地早熟禾）在西宁地区的株高生长进程。结果表明：在生育期内禾草的生长速度不一致，生长曲线呈Ｓ形；用对称Ｓ形曲线模拟和Ｌｏｇｉｓｔｉｃ生长曲线模拟后，四种禾草的Ｓ形曲线间有差异，因而生长高峰期的到来也有差异，草地早熟禾出现最早，为返青后的第３８（或３９）ｄ，紫羊茅出现最晚，为返青后的第５４（或５５）ｄ，平均生长速度和最大生长高度也有差异，冷地早熟禾最大，分别为０．５６ｃｍ／ｄ和５６ｃｍ，草地早熟禾最小，分别为０．３８ｃｍ／ｄ和３０ｃｍ。     

Azuche, Hymenachne amplexicaulis (Rudge) Nees, Forage Genetic Resources for Floodplains in Tropical Mexico

Azuche Hymenachne amplexicaulis (Rudge) Nees is a C₃ grass native to tropical flooded areas in South and Central America with 2n = 2x = 24 chromosomes. During 2002 and 2003, the Graduate College for Agricultural Sciences (CP) and the Mexican Institute for Forestry, Agriculture and Animal Production Research (INIFAP) organized an expedition to collect the genetic diversity of this species within tropical Mexico, in order to preserve and study it under nursery conditions. The collection was performed from Puerto Vallarta to Tapachula on the Pacific and from Palizada, Campeche to Veracruz on the Gulf of Mexico coast, and also crossing sections through the Tehuantepec isthmus and through the Sierra Madre de Chiapas. Ninety sites were sampled, on each, 25 tillers were collected, tagged and stored in a commercial soil mix until establishment of individual plants within 6 l pots. The largest Azuche prairie observed had a 10 ha surface, with the grass limited to small surfaces of up to 0.25 ha. It was not found on places with salty water, even seasonally. The Pacific coastal side is less abundant in niches for this species. Producers’ experience indicated that this grass is beneficial for milk production compared with other forage grasses, mainly C₄, growing in flooded areas. Initial studies of genetic diversity showed wide morphological variation for sprouting ability, leaf width and length among samples. Azuche diversity showed good potential production attributes for farm and wild animals, under flooding tropical savanna conditions.     

几种冷季型草坪草在关中地区的引种试验

通过对5种引种草坪草的物候期、覆盖度、生长速度、生物量及抗逆性等方面的综合研究,结果表明:5种草坪草均适宜在陕西关中生长.多年生黑麦草Lolium perenne品种爱神特和佳丽2号抗性较差;其中爱神特生长速度比佳丽2号快;而佳丽2号植株低矮、生长缓慢,可以减少修剪次数,降低管理成本.高羊茅Festuca arundinacea品种贝克、美洲虎3号和火凤凰绿期较黑麦草长,尤其是抗性强,对环境条件的要求较低,其中火凤凰更适合于高温干旱低养护管理的条件.