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61.
D. Shane Hennigh Kassim Al-Khatib Randall S. Currie Mitchell R. Tuinstra Patrick W. Geier Phillip W. Stahlman Mark M. Claassen 《Crop Protection》2010
The recent development of grain sorghum hybrids with resistance to acetolactate synthase (ALS)-inhibiting herbicides has allowed for the use of several post-emergence applied (POST) ALS-inhibitors to control weeds in the crop. Field experiments were conducted at four sites in Kansas in 2008 to evaluate the efficacy of nicosulfuron and nicosulfuron + rimsulfuron applied alone or in combination with dicamba, metsulfuron methyl, and atrazine. All POST treatments slightly injured sorghum 2 weeks after treatment (WAT) at Garden City and Hesston, whereas at Hays and Manhattan, only treatments that included dicamba caused injury. Nicosulfuron + rimsulfuron applied alone provided 41, 83, 74, and 93% control of grasses 4 WAT at Garden City, Hays, Hesston, and Manhattan, respectively. However, to obtain the highest level broadleaf weed control, nicosulfuron or nicosulfuron + rimsulfuron need to be applied with other broadleaf herbicides. POST treatment of nicosulfuron + metsulfuron methyl + dicamba + atrazine provided 90% or greater control of all broadleaf weeds at sorghum flowering. Sorghum grain yield was greater following all herbicide treatments compared with the weedy check. The POST treatment that provided the highest yield at Garden City was nicosulfuron + rimsulfuron + atrazine, whereas in Hesston and Manhattan, nicosulfuron + metsulfuron methyl + dicamba + atrazine provided the highest yields. This research showed that many grasses can be effectively controlled with POST applications of nicosulfuron or nicosulfuron + rimsulfuron in ALS-resistant sorghum. The research also indicated that broadleaf weed control is greater when nicosulfuron or nicosulfuron + rimsulfuron are applied with other broadleaf-control herbicides such as dicamba, metsulfuron methyl, and atrazine. 相似文献
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63.
Kaiwen Pan Zhihong Xu Timothy J. Blumfield Shane Tutua Manxin Lu 《Journal of Soils and Sediments》2009,9(6):515-525
Purpose
Hoop pine (Araucaria cunninghamii) is a nitrogen (N)-demanding native Australian softwood plantation species. Litter quality and its effects on soil mineral N and 15N transformations have not been well studied in the hoop pine plantation and adjacent native forest. The present study was conducted to determine the impact of 15N injection depth and litter additions on the dynamics and fate of mineral 15N and also to compare the difference in litter quality, 15N dynamics, and fate between the hoop pine plantation (HP) and the adjacent native forest (NF).Materials and methods
The experiments were done in the Yarraman State Forest (26°52′ S, 151°51′ E), southeastern Queensland. Materials of litter addition were prepared on the basis of ten random samples of litters taken from the NF and HP sites using a 1?×?1-m quadrat. Litter additions were defined as: SL represented the average condition of forest floor in the forest ecosystems and DL represented the double average amount of litters in the forest ecosystem. Experiment 1 covered 2 forest types (NF and HP)?×?3 litter rates (nil litter, SL, and DL)?×?3 15N injection depths (0, 2.5, and 5.0 cm). Experiment 2 included 2 forest types (NF and HP)?×?2 litter rates (nil litter and SL)?×?3 injection depths (0, 2.5, and 5.0 cm) of distilled water. The in situ core incubation method was used with an incubation period of 28 days. The isotope ratio of mineral N or/and total N (soil and litter) were analyzed using an isotope ratio mass spectrometer with a Eurovector elemental analyzer (Isoprime-EuroEA 3000).Results
Total N and δ 15N were significantly higher, and C/N ratios and δ 13C were significantly lower in the NF litters than in the HP litters. The NF litters had significantly lower total 15N and total 15N recovery than the HP litters after 15N addition. Litter addition had no significant effect on mineral 15N transformations and δ 15N in the NF soil, but decreased 15NO 3 ? –N, mineral 15N, and δ 15N and increased immobilized 15N in the HP soil. The depth of added 15NH 4 + significantly altered total 15N, δ 15N, and total 15N recovery in the litters, whereas it did not influence 15NH 4 + –N, 15NO 3 ? –N, mineral 15N, or immobilized 15N in soils in the two forest ecosystems.Discussion
The NF litters had significantly higher δ 15N than the HP litters, indicating that the NF soil had a higher rate of nitrification than the HP soil. Higher litter quality in the NF was an important driving force for N cycling to promote strong N dynamics in the NF soil over the HP soil. The HP litters had significantly higher total 15N than the NF litters after 15N addition, implying that soil mineral N was relatively deficient in the HP in comparison with the NF. Litters decreased nitrification and increased immobilization in the HP soil, showing forest litters resulted in more N immobilization to prevent the loss of substantial quantities of NO 3 ? through leaching or denitrification. The depth of 15N injection did not significantly alter concentrations of 15NH 4 + –N, 15NO 3 ? –N, mineral 15N, and immobilized 15N in the NF and HP soils, suggesting that the depth of 15N injection had no significant influence on the evaluation of soil N transformations.Conclusions
The NF litters had significantly higher total N and δ 15N and lower C/N ratios and δ 13C than the HP litters. Mineral N was relatively insufficient in the HP soil relative to the NF soil. The HP litters facilitated more N immobilization in the soil to reduce the loss of substantial quantities of NO 3 ? through leaching or denitrification. The depth of 15N added did not significantly alter concentrations of 15NH 4 + –N, 15NO 3 ? –N, mineral 15N, and immobilized 15N in the NF and HP soils. The application of 15N solution by uniform sprinkling onto the soil surface can be used to study in situ field N (including mineral 15N) transformations in the 10-cm depth soils of both forest ecosystems. 相似文献64.
DM Magalhães DD Fernandes MBS Mororó CMG Silva GQ Rodrigues JB Bruno MHT Matos CC Campello JR Figueiredo 《Reproduction in domestic animals》2011,46(1):134-140
The aim of the present study was to evaluate the effects of different medium replacement intervals on the viability, antral cavity formation, growth and in vitro maturation (IVM) of oocytes from caprine and ovine pre‐antral follicles. Pre‐antral ovarian follicles (≥150 μm) were isolated from the ovarian cortex of goats and sheep and were individually cultured for 24 days using two different medium replacement intervals [2 days (T1) or 6 days (T2)]. Follicle development was evaluated on the basis of antral cavity formation, increases in follicular diameter and the presence of healthy cumulus oocyte complexes and fully grown oocytes. For caprine species, results showed a higher percentage (p < 0.05) of viable follicles in T1 than T2 from day 6 until the end of the culture. In addition, when comparing both treatments after the same culture duration, the rate of antrum formation was significantly higher in T1 than in T2 from day 12 onwards. Yet, in ovines, when both treatments were compared on day 24 of the culture, there were more viable follicles in T2 than in T1 (p < 0.05). In the caprine species, percentages of fully grown oocytes (≥110 μm) acceptable for IVM after 24 days of culture were significantly higher in normal follicles cultured in T1 (30.0%) than in T2 (6.7%; p < 0.05). On the other hand, in ovines, at the end of the culture, the percentage of oocytes destined for IVM was higher in T2 than in T1 (23.5% vs 2.9%; p < 0.05). In conclusion, under the same conditions, the frequency of medium replacement significantly affected the in vitro development of caprine and ovine pre‐antral follicles. To improve the efficiency of the culture system, the medium must be replaced every 2 and 6 days for goat and sheep pre‐antral follicles, respectively. 相似文献
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66.
疫病是世界养禽生产效率的主要限制因素。尽管分子生物学方面的基础研究导致了新型疫苗的出现,但集约化生产体系仍受到新的和变异疫病的危害,这常常是多因子感染造成的。本文综述了一些重要疫病复合症的研究进展并对商品蛋鸡群和肉鸡生产效益的影响作一评述。 相似文献
67.
Effects of pH, temperature, and salinity on persistence of avian influenza viruses in water 总被引:5,自引:0,他引:5
The combined effects of water temperature, salinity, and pH on persistence of avian influenza virus (AIV) were evaluated in a model distilled-water system using three isolates from ducks sampled in Cameron Parish, Louisiana. Variables were tested within the ranges normally associated with surface water. Differences were detected between temperature (17 C and 28 C), pH (6.2, 7.2, 8.2), and salinity (0 ppt and 20 ppt), with a strong interactive effect observed between pH and salinity. Estimated persistence of infectivity for 1 x 10(6) mean tissue-culture infective dose of A/mottled duck/LA/38M/87 (H6N2) was longest at 17 C/0 ppt/pH 8.2 (100 days) and shortest at 28 C/20 ppt/pH 8.2 (9 days). Differences in the response to these variables were apparent between viruses. The ability of AIV to persist in surface water was also evaluated using samples collected from varied waterfowl habitats in coastal Louisiana. Observations were consistent with the model system, with duration of infectivity decreasing with increased salinity and pH. This suggests that experimental results may have application to field conditions. 相似文献
68.
JB THOMAS 《Australian veterinary journal》1988,65(8):252-254
A large tumour present on the proximal tibia of a Bull Mastiff dog was diagnosed on histological appearance as a Malignant Fibrous Histiocytoma. These tumours, rarely identified in domestic animals, but well recognised in humans, are typically pleomorphic sarcomas with histiocytic and fibroblastic differentiation. Less commonly, one cell type predominates. In this case there was prominent histiocytic differentiation. 相似文献
69.
A case of generalised protothecosis in a Collie dog is discussed. A long-standing history of severe colitis was the major clinical sign. Dissemination to many organs was confirmed histologically. Possible pathogenesis is discussed along with a review of the literature. The possibility of a breed disposition in Collie dogs is discussed. The organisms are ubiquitous in the environment and generalised disease suggests the possibility of immune competence. 相似文献
70.
Cloacal and tracheal swabs were collected from 1389 hunter-killed ducks in Cameron Parish, Louisiana, during the 1986 and 1987 waterfowl seasons. Twenty-eight avian influenza viruses (AIVs) were isolated from 605 blue-winged teal (Anas discors), 75 mottled ducks (A. fulvigula), 375 gadwalls (A. stepera) and 334 green-winged teal (A. crecca). Prevalence estimates of AIV in ducks sampled during September, November, and December through January were 3.1%, 2.0%, and 0.4%, respectively. Differences in prevalence were detected by season (P = 0.044) and age class (P = 0.036). Two isolations from resident mottled ducks document transmission of AIV on these wintering areas. Much subtype diversity was present, with nine of 13 hemagglutinin (HA) and nine of nine neuraminidase (NA) subtypes recovered. Predominant HA and NA subtypes were typical of AIVs commonly associated with waterfowl. Results indicate that AIVs are transmitted in the wintering areas, and, although prevalence is low, these viruses continue to circulate within these duck populations during winter. 相似文献