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ABSTRACT: The present study, one in a series to clarify the phosphorus (P) and nitrogen (N) loading from carp culture, evaluated four commercial diets. The total and available P in these diets varied from 1.57 to 1.86% and from 0.38 to 0.87%, respectively. The control diet, selected based on an earlier experiment, contained 1.40% total P and 0.68% available P. The 7-week feeding trial was performed with juvenile carp. Superior feed gain ratio was obtained for the control diet (1.00) and it varied from 1.19 to 1.56 among the commercial diet groups. Similarly, the control diet showed higher rates of P absorption (43.8%) and retention (33.1%) than the rest (absorption: 18.1–40.9%; retention: 10.7–18.7%). Total P loading (kg/t production) was 10.0 for the control group but ranged from 19.1 to 25.0 among the commercial diet groups. Nitrogen absorption was not markedly different; however, fluctuations in retention resulted in N loading (kg/t production) that ranged between 47.1 and 66.3 among the commercial diets, higher than the 34.8 obtained for the control diet. The available P in the commercial diets rarely matched the requirement level, thereby negatively affecting the waste loading. The superior performance of the control diet underscores the fact that effective formulations help in keeping emission levels low. 相似文献
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ABSTRACT: Through a series of experiments, it has been demonstrated successfullythat an appropriate choice of ingredients is primary for achievinga reduction in phosphorus (P) and nitrogen (N) loading from carpculture. In this final study, four multi-ingredient diets were examined.In addition to the basal ingredients (fish meal 15%, corngluten meal 8%, defatted soybean meal 10%, blood meal3–5%), three of the test diets (PF, MM, and SP)contained 6% each of either poultry feather meal, meatmeal or soy protein concentrate, respectively, and the fourth diet(PMS) had each of the three aforementioned ingredients includedat 3%. These diets had crude protein < 35%,digestible energy > 3.5 kcal/g,available P between 0.65 and 0.66% and total P rangingfrom 1.26 to 1.36%. The diets were fed to juvenile carpduring a 12-week feeding trial. The highest growth was obtained forfish fed the MM diet. The absorption and retention rates of P werehigher for the PF diet, whereas these values for N did not showtreatment-related differences. The total discharges per ton fish productionwere estimated to range between 7.8 and 9.2 kg for P andbetween 39.1 and 40.7 kg for N. These were lower than thefigures for Lake Kasumigaura, a main carp culture site, indicatingthat proper balancing of protein ingredients aids in efficientlylowering emissions from aquaculture. 相似文献
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Rice yield losses by competition with weeds in rainfed paddy fields in north-east Thailand 总被引：2，自引：0，他引：2
SHINSUKE TOMITA SHUICHI MIYAGAWA YASUYUKI KONO CHAIRAT NOICHANA TATSUYA INAMURA YOSHIKATSU NAGATA AKKADET SRIBUTTA EIJI NAWATA 《Weed Biology and Management》2003,3(3):162-171
Economic growth in recent years has induced a labor shortage for agriculture in north-east Thailand. Labor-saving techniques, such as the replacement of transplanting with direct seeding, have become widespread. Direct seeding methods have advantages over transplanting regarding labor savings and reductions in production risks, but may cause weed problems. Therefore, rice yield reduction by competition with weeds becomes a potential problem in this region. In the present research, the extent of weed competition in rice production from the viewpoint of resource level and disturbance intensity was studied. A large number of paddy fields from a wide range of climatic, topographical, soil and hydrological conditions were analyzed. The survey was conducted every 3 weeks, and data on paddy cultivation, weeds and water conditions were recorded. Average yield of direct seeded rice was significantly lower than that of transplanted rice. The yield decreased with resource decreases in both direct seeded (DSF) and transplanted paddy fields (TF). Although the yield was not different under resource-rich conditions, the yield of direct seeded rice was lower than that of transplanted rice under resource-medium and -poor conditions. Competition intensity was not different among resource levels or between DSF and TF. Competition intensity in all fields was between 0.02 and 0.09 on average, indicating 2–9% yield losses caused by competition with weeds regardless of resource level and disturbance intensity. This suggests that low yield of direct seeded rice under resource-medium and -poor conditions was not mainly caused by competition with weeds, whereas yield losses by weeds were observed in all field types. However, from an economical viewpoint, weeding should be applied only to limited parts of this region with stable and relatively high rice yields. 相似文献
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AKIRA UCHINO SHIGERU OGATA HIROSHI KOHARA SHUICHI YOSHIDA TOSHIHITO YOSHIOKA HIROAKI WATANABE 《Weed Biology and Management》2007,7(2):89-96
Sulfonylurea-resistant biotypes of Schoenoplectus juncoides were collected from Nakafurano, Shiwa, Matsuyama, and Yurihonjyo in Japan. All of the four biotypes showed resistance to bensulfuron-methyl and thifensulfuron-methyl in whole-plant experiments. The growth of the Nakafurano, Shiwa, and Matsuyama biotypes was inhibited by imazaquin-ammonium and bispyribac-sodium, whereas the Yurihonjyo biotype grew normally after treatment with these herbicides. The herbicide concentration required to inhibit the acetolactate synthase (ALS) enzyme by 50% (I50), obtained using in vivo ALS assays, indicated that the four biotypes were > 10-fold more resistant to thifensulfuron-methyl than a susceptible biotype. The Nakafurano, Shiwa, and Matsuyama biotypes exhibited no or little resistance to imazaquin-ammonium, whereas the Yurihonjyo biotype exhibited 6700-fold resistance to the herbicide. The Nakafurano and Shiwa biotypes exhibited no resistance to bispyribac-sodium, but the Matsuyama biotype exhibited 21-fold resistance and the Yurihonjyo biotype exhibited 260-fold resistance to the herbicide. Two S. juncoides ALS genes (ALS1 and ALS2) were isolated and each was found to contain one intron and to encode an ALS protein of 645 amino acids. Sequencing of the ALS genes revealed an amino acid substitution at Pro197 in either encoded protein (ALS1 or ALS2) in the biotypes from Nakafurano (Pro197 → Ser197), Shiwa (Pro197 → His197), and Matsuyama (Pro197 → Leu197). The ALS2 of the biotype from Yurihonjyo was found to contain a Trp574 → Leu574 substitution. The relationships between the responses to ALS-inhibiting herbicides and the amino acid substitutions, which are consistent with previous reports in other plants, indicate that the substitutions at Pro197 and Trp574 are the basis of the resistance to sulfonylureas in these S. juncoides biotypes. 相似文献
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ABSTRACT: As part of on-going efforts to reduce environmental phosphorus(P) and nitrogen (N) loading from culture systems, five experimentaldiets were formulated containing 5–15% of fishmeal (FM) and different levels of soy protein concentrate (10–20%),corn gluten meal (3–5%) and defatted soybean meal(2.0–8.5%). These diets had total P ranging between1.04 and 1.29% and available P between 0.62 and 0.63%.A FM-based (43%) commercial diet was used as the controland this diet had total P of 1.87% and available P of 0.82%.Waste loading was calculated after feeding the diets to 3.4 gcarp for 10 weeks. Feed gain ratios were not significantly differentfor fish fed control and experimental diets having 10–15% FM,but the protein efficiency ratio was lower for the control group.The rates of P absorption and retention in the experimental dietgroups were significantly higher than those of the control group.The lowest N retention was obtained for the control group, althoughabsorption was not markedly different among the treatment groups.Total P and N loading (kg/ton production) produced fromthe experimental diets ranged from 7.1 to 8.9 and from 36.1 to 41.3,respectively, whereas the corresponding values for the control dietwere 15.2 and 48.1. 相似文献
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Competition between weeds and wet season transplanted paddy rice for nitrogen use, growth and yield in the central and northern regions of Laos 总被引：2，自引：0，他引：2
TATSUYA INAMURA SHUICHI MIYAGAWA OLAYVANH SINGVILAY NIVONG SIPASEAUTH YASUYUKI KONO 《Weed Biology and Management》2003,3(4):213-221
To quantify the effect of weeds on the nitrogen (N) use, growth and yield of wet season paddy rice in the central and northern regions of Laos, we surveyed the paddy fields in these regions in October 1999 and November 2000. We found 13 weed species in total, but there were few major weeds abundant at the survey sites. In the infertile soils under rainfed conditions, weed growth was poor. Rough rice yield, the number of panicles, the number of seeds per square meter, the above-ground biomass of paddy rice and the amount of N accumulated in the above-ground biomass of paddy rice (amount of N in rice) were suppressed by competition with weeds. However, harvest index (HI) and nitrogen use efficiency (NUE) of paddy rice were not suppressed by competition with weeds. The amount of N in rice was suppressed by competition with weeds, the number of panicles decreased as the amount of N in rice decreased, and the number of seeds per square meter decreased as the number of panicles decreased. As a result, rough rice yield was suppressed by competition with weeds. The weeds competed with paddy rice for N uptake during the productive tillering stage. However, the ability of paddy rice to compete for N uptake with weeds was not reduced under rainfed lowland conditions. When the weeds were completely removed, the amount of N in rice increased. Rough rice yield may be increased by 10% under rainfed lowland conditions and by 17–19% under irrigated conditions. 相似文献
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ABSTRACT: The effect of dietary phosphorus (P) manipulation on environmental loading of P and nitrogen (N) from carp was investigated. Two commercial diets (A and B) were re-prepared as four experimental diets A, B, AP, and BP, the latter two being topped up to the required available P level for carp. The total P ranged between 1.52 and 1.99% and water-extractable (or available) P was 0.50, 0.36, 0.62, and 0.63% for A, B, AP, and BP, respectively. A 20% fishmeal diet was chosen as the control and it contained 1.41% total P and 0.67% water-extractable P. Duplicate groups of carp (size, 8.6 g) were fed the test diets for 12 weeks. The best growth performance was that of fish fed the control diet, followed by the test diets supplemented with P. The highest rates of P absorption and retention of P and N were obtained for the control group followed by the AP, A, BP, and B experimental groups. In the case of waste discharge, the reduction in P loading was marginal, but N loading was markedly lower for P supplemented test diets. The control diet was the least-loading diet. Thus commercial carp feed formulations could be improved by incorporating sufficient available P in order to reduce discharges of P and N into the water. 相似文献
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ABSTRACT: Two feeding trials were performed on carp to investigate phosphorus (P) and nitrogen (N) excretion during their growth span. Trial I was conducted under laboratory conditions by feeding 3.9 g carp an experimental diet (crude protein 34.8%, total P 1.41% and available P 0.67%) for 280 days under controlled conditions. Trial II was performed with 72.8 g carp, feeding them a commercial diet (CP 35.8%, total P 1.62% and available P 0.75%) for 180 days on a practical scale. Fish grew throughout the experiment in trial I, whereas they stopped growing in trial II when the water temperature fell below 15°C. In both trials, P and N content in fish body increased with increasing weight until it plateaued when fish were between 500 and 600 g. The retention rates of the two elements also followed a similar pattern, but decreased beyond the size range mentioned above. In both trials, P and N loading increased with an increase in fish size, but such a pattern was less evident until a bodyweight of 600 g, the trend being more pronounced in trial II. The results of the present study indicate that excretion is higher during the slow-growing stage of carp and is, hence, influenced by fish size. 相似文献
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