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Survey of the environmental impacts of pond fish farming
19-24Views:94The aim of this study was to survey the nitrogen, phosphorus and organic matter loads and the discharge of fishponds. The inputs and outputs of nutrient amounts of fishponds and their sources are described. The impact of a fishpond on the nutrient loads of receiver waters was determined. The investigations of this study were to determine and evaluate the nitrogen, phosphorus and organic matter budget of fishponds representing different technologies and areas.
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Experiments on the Nutrient Removal and Retention of an Integrated Pond System
18-23Views:205A combined intensive-extensive fishpond system developed for the purification and re-use of intensive fishpond effluent water was studied during a three-year experimental period. The investigated pond system consists of five small-size intensive culture ponds of 1 ha total water surface area with 1.5 m water depth and a 20 ha extensive culture pond with 1.0 m average water depth. The water was recirculated between the intensive and extensive ponds with around 60 days retention time in the extensive treatment pond.
Carbon, nitrogen and phosphorus budget and water purifying capacity were described and evaluated by means of regular measurements of nutrient concentrations in the water and sediment. During the three-year test period, 81.5% of organic carbon, 54.7% of nitrogen and 72.2% of phosphorus were retained by the system as a percentage of the total input of each nutrient. A significant amount of the total nitrogen input was removed by the harvested fish, which was much higher than in traditional fishponds or intensive fish culture systems. The efficiency of nutrient removal is clearly indicated by the 27.3% nitrogen assimilation.
Only a small percentage of the total nutrient input was discharged into the environment during fish harvest, which was 9.0% for organic carbon, 13.2% for nitrogen and 12.1% for phosphorus. The combination of intensive and extensive fishponds with water recirculation resulted in significant reduction of nutrient discharge into the surrounding aquatic environment, primarily due to the high nutrient processing and retention capacity of the extensive fishpond ecosystem. -
Micropropagation of Rudbeckia hirta L. from seedling explants
53-59Views:119We conducted experiments for developing an in vitro micropropagation protocol starting from meristems of Rudbeckia hirta L seedlings. We pre-soaked the seeds in sterile ion-exchanged water for 17 hours, and then achieved surface disinfection in two separate steps. First, we used concentrated household sodium-hypochloride solution for 20 minutes and, also for 20 minutes, we applied hydrogen peroxide of 10%, which was followed by washing with sterile ion-exchanged water three times. For the propagation of seedling meristems, the combination of half-strength solid Murashige and Skoog (1962) culture medium containing 10 mg/l of kinetin and 2 mg/l of kinetin + 0.1 mg/l of 2iP proved to be the most suitable. The average number of shoot-buds developed from the seedling axillary meristem in the best culture media varied between 5 and 17. Without separating them, we inoculated the shoot-bud clusters on MS culture medium containing 2 mg/l of IAA. After four weeks of incubation, we obtained elongated shoots, which we separated and inoculated into a new culture medium and from which we obtained elongated roots. The rooted plants were gradually acclimatised in the cultivation room, potted and carried to a greenhouse, and then planted in open field for subsequent observation. By adopting this method, our laboratory started the micropropagation of the superior and/or elite genotypes of the Rudbeckia hirta L. being of special value in respectt to breeding.
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Alternatives of the multiple use of Virginia mallow (Sida hermaphrodita L. Rusby) as a shrub-replacing mallow in the temperate climate zone
51-56Views:172In the seventies of the previous century, Dr. Zoltán Kováts set two directions in the research of mallows. One of the directions was the biotechnology of the mallow species and the other direction is using the mallow species as biomass material. In order to do this he brought mallow mother spawns of ornamental and biomass sorts from botanical gardens abroad and tested many of them, including the a Sida hermaphrodita kind. Fourty years later, for the second time this plant, known as the „energy mallow” got back to Hungary again, right into the sight of hungarian biomass business with the help of László Balogh and his associates using help from Poland. This genus got into the center of our research, because of it’s valuable attributes. The latest experiments are about using it as an energy plant, without examining genetic details. The plant grows up to more
than 3 meters, has high growing rate and produces big amount of green mass. We don’t have any hungarian data about whether the plant continues the sufficient growing rate or not, after cutting it back.
We have to explore the potentials in the Sida’s sublimation. The plant is mostly suitable for ornamental and energy utilization, so further sublimation should be aiming for these aspects. During my research period, we are willing to get to know these potentials and the best possible use of them.