199,070 research outputs found
Control of macrophytes by grass carp (ctenopharyngodon idella) in a Waikato drain, New Zealand
No full textHornwort (Ceratophyllum demersum L.) and other aquatic macrophytes have historically been mechanically removed from the Rangiriri drain and Churchill East drain to maintain drain efficiency. As an alternative control method for the high plant biomass that accumulates at the end of summer, the effect of stocking diploid grass carp (Ctenopharyngodon idella L.) on the aquatic vegetation was evaluated in these Waikato drainage systems. At the start of the trial, both drains had a low diversity of aquatic macrophytes, and of the nine species (including the emergents), seven were exotic. Two months after grass carp were released to Churchill East drain (the treated drain) the four submerged and floating macrophyte species became scarce in the main drain. Over the same period, these species increased in biomass in Rangiriri drain (the untreated drain), where hornwort became dense and surface-reaching and remained so for the duration of the trial. However, grass carp did not control submerged vegetation in smaller side drains or the shallow, upper parts of the main drain, or the marginal sprawling species and emergent species. The cost of leasing the grass carp was similar to the cost of clearing the drains mechanically, but grass carp provided continuous weed control. However, subsequent to this trial, 62 dead grass carp were found in Churchill East drain in February 2001, and weed cover subsequently increased. This illustrates that grass carp management in New Zealand agricultural drains can be problematic due to periodic fish kills
Grass Valley Notice of Adopted Amendment (2007-07-02)
No full text63 pp. Adopted 2007-07-02. Department of Land Conservation and Development Notice of Adopted AmendmentThis is the final adoped product of a TA Grant from the Department to update the City's Comprehensive Plan, the project is listed as TA-R-07-029. This is a general update of the Plan inventories and policies. The Comprehensive Map is unchanged, except for the adoption date
The new GRASS 5.1 vector architecture
No full textThe presentation describes the new GRASS 5.1 vector library architecture. This new architecture overcomes the vector limitations of GRASS 4.x-5.0 by extending the vector support with attributes stored in external relational databases and by new 3D capabilities. Besides internal file based storage the geometry may alternatively be stored in PostGIS database. This enables users to maintain large data sets with simultaneous write access. External GIS formats such as SHAPE-files may be used directly without necessity of format conversio
The use of reed canary-grass (Phalaris arundinacea) as a short fibre raw material for the pulp and paper industry
No full textThis thesis describes the use of delayed harvested reed canary-grass (Phalaris arundinacea) as a short fibre raw material for the pulp and paper industry. This study examines the following aspects of reed canary-grass: quality, transportation, storage, refining of the raw material by dry fractionation, chemical pulping, bleaching and paper production. The delayed harvesting method of reed canary-grass produces an economically and environmentally sustainable short fibre raw material for the pulp and paper industry. The ash content and fibre properties of reed canary-grass depend on soil type and growing location. The yearly variation in fibre yield and fibre properties is also considerable. There is, however, a potential for minimising quality variations by choosing reed canary-grass varieties suitable to a specific growing location. The leaf and leaf sheath content of reed canary-grass also affects the quality of the pulp. These quality variations can be eliminated by dry fractionation, a method that removes the unwanted parts of the grass. These unwanted parts can be used as a valuable bio-fuel raw material. Transport of reed canary grass after fractionation can be improved by briquetting, a method that doubles the transport capacity of reed canary-grass compared to that of birch logs on a fibre basis. High quality short fibre chemical pulp can be produced from reed canary-grass. The whole process from grass production to pulp production has been demonstrated successfully in full scale. Bleached reed canary-grass pulp can be used in products such as fine paper and white-top liner paper
Fish and macroinvertebrates in lowland drainage canals with and without grass carp
No full textDiploid grass carp (Ctenopharyngodon idella
L.) were introduced to a lowland Waikato drainage canal at an initial density of 40-80 kg ha -1(83-167 fish ha -1) to control aquatic macrophytes and improve water flow. A near-by canal was left without grass carp to act as an untreated control. After 7 months, macrophytes occupied 17% of the water column in the treated canal compared to 78% in the untreated canal. Fish and macroinvertebrates in both canals were examined before and after the release of grass carp by sampling with replacement by fyke netting on seven occasions. Brown bullhead catfish (Ameiurus nebulosus (Lesueur)) and shortfinned eels (Anguilla australis Richardson) comprised most of the
resident fish biomass in both canals; however, before grass carp stocking, eels were more abundant than catfish in the
treated canal. There was no change in the abundance of resident fish after stocking, but young-of-the-year catfish had greater mortality and grew faster in the treated canal than in the untreated canal. Macroinvertebrates were primarily associated
with aquatic macrophytes. Grass carp reduced aquatic macrophyte abundance in the treated canal by about 80%, which by inference reduced the abundance of associated macroinvertebrates, but there was no observed impact of grass carp stocking on the resident fish assemblage. We examined
the relationship between head width and fish length, and from this determined that 70% of the grass carp could have escaped through the downstream retention screen. Despite
this possibility, grass carp remained in the canal and effectively controlled aquatic macrophytes for 18 months
Requirements of future grass-based ruminant production systems in Ireland
No full textpeer-reviewedThere is a renewed interest in grazing systems in many temperate and subtropical regions of the world. This results from lower inflation-adjusted prices, the proposed removal of some subsidies and tariffs, and rising labour, machinery and housing costs. The utilization of grass by grazing should provide the basis of sustainable livestock systems as grazed grass is the cheapest source of nutrients for ruminants. This is very important in the Irish context as there are approximately 130 000 farmers involved in primary production in Ireland and the value of the goods produced was €5.8 billion in 2008. For the future, the key objective for grazing systems is to ensure high grass utilization,
allowing increased output per hectare for all sectors. The primary emphasis in grass
breeding needs to be focused on (i) seasonal growth pattern as well as overall annual
growth, (ii) nutritive value, including digestibility, particularly in the mid-season period, (iii) ensuring a sward canopy structure that is suitable for grazing, and (iv) development of persistent cultivars that perform under farm conditions. Evaluation programmes should also consider including an estimate of production potential at the field as well as at plot level, and evaluation under grazing management systems as well as under mixed grazing/silage management systems. It is difficult to accurately quantify the breeding achievements for grass mainly because its value, whether grazed or conserved, must be indirectly realised through the output of animal product. Grass evaluation and breeding need to better accommodate the requirements of the grazing ruminant. This will necessitate the application of new approaches and knowledge, which will ultimately enable further increases in animal output per hectare to be achieved
Identification of universal grass genes and estimates of their monocot-/commelinid-/grass-specificity
No full textThe evolutionary success of grasses is due to characteristics of resilience and fast growth in open habitats that led to their underpinning of agriculture and is attributable to many grass-specific traits. Genes responsible for these traits are likely specific to grasses, highly conserved and present in all grasses (universal genes) as they perform essential functions for fitness. A bioinformatics pipeline was developed to identify such genes using 16 grass full genomes in Ensembl Plants release 56. The first steps used existing gene models to generate groups of grass orthologs to rice and maize genes present in most grass species and refined membership of these groups such as to optimise the Hidden Markov Model (HMM) profile score from the HMMER package. These were then supplemented using new gene models found in grass genomes with the genBlastG tool; this step increased the number of universal groups by >2-fold to give 12,855 highly conserved, universal groups. Specificity for these groups was assessed using closest matching gene models from non-monocot species. Possible cut-off values were tested with sets of known genes expected to be either of common function for all plants, or of commelinid- / grass-specific function. A specificity metric based on HMM score from grass group profiles performed better than % identity as a means of discriminating between these common and specific function test sets. Using an appropriate cut-off for this metric, 5,701 of the groups were identified as monocot- / commelinid- / grass-specific of which 72% appeared to be grass specific. These results comprise the universal_grass_peps database available at DOI doi.org/10.23637/rothamsted.98ywz. This database can be searched by researchers to determine whether their experimentally identified grass genes match universal groups and, for those that do, to obtain systematic estimates of monocot- / commelinid- / grass-specificity
Couplage R - GRASS : appeler des fonctions GRASS dans R
No full textGRASS est un logiciel SIG libre qui dispose de nombreuses fonctions de traitement d'objets spatiaux, aussi bien raster que vectoriel. Le tutoriel suivant montre un exemple de couplage entre R et GRASS, plus précisément il montre comment appeler une fonction de GRASS dans R. La fonction utilisée est v.generalize qui permet de simplifier la géométrie d'un objet vectoriel. Le tutoriel au format html et pdf ainsi que les données nécessaires sont disponibles avec ce lien de téléchargement : Coupla..
Couplage R - GRASS : appeler des fonctions GRASS dans R
No full textGRASS est un logiciel SIG libre qui dispose de nombreuses fonctions de traitement d'objets spatiaux, aussi bien raster que vectoriel. Le tutoriel suivant montre un exemple de couplage entre R et GRASS, plus précisément il montre comment appeler une fonction de GRASS dans R. La fonction utilisée est v.generalize qui permet de simplifier la géométrie d'un objet vectoriel. Le tutoriel au format html et pdf ainsi que les données nécessaires sont disponibles avec ce lien de téléchargement : Coupla..
Effect of cutting management and nitrogen supply on yield and quality of Napier grass (Pennisetum purpureum)
No full textIn a series of cutting experiments, average apparent nitrogen recovery of applied fertilizer N by Napier grass was approximately 50%. Incorporation of cattle manure improved nitrogen utilization. Mixtures with Desmodium intortum substantially improved yield and protein content. There was a fair to good relation between morphology and crude protein content and in vitro organic matter digestibility of Napier grass
- …
