排序方式: 共有41条查询结果,搜索用时 15 毫秒
21.
Kassu Tadesse Kassaye Almaz Admassu Tirfe Wubengeda Admasu Yilm Dawit Habte Haile Asrat Mekonnen Teto Amare Tadesse Weldegebriel 《Journal of plant nutrition》2013,36(19):2525-2535
AbstractSoil fertility depletion coupled with improper fertilization is one of the major constraints limiting linseed production in Ethiopia. Experiment was conducted in 2014/2015 on Nitisol in southeastern Ethiopian highlands to study the effect of phosphorus (P) fertilizer rate on yield, yield components, and oil content of linseed. It comprised of six levels of P fertilizer (0, 5, 10, 15, 20, and 25?kg?P?ha?1) arranged in randomized complete block design with three replications. Results revealed that P fertilization brought significant effect on biomass yield, harvest index, plant height, number of capsules per plant, and kernel size. However, it didn’t significantly increase seed yield and oil content on linseed. Considering its influence on increasing biomass yield and improving yield components, application of 5?kg?P?ha?1 has been recommended for replenishing the extracted P, maintaining soil fertility and improving linseed production on Nitisols of southeastern Ethiopian highlands and other similar agro-ecologies. 相似文献
22.
Jerry Celumusa Dlamini Eyob Habte Tesfamariam Robert Dunn J. Evans Jane Hawkins Martin Blackwell Adrian Collins Laura Cardenas 《植物养料与土壤学杂志》2023,186(4):406-416
Background
Riparian buffers are primarily implemented for their water quality functions in agroecosystems. Their location in the agricultural landscape allows them to intercept and process pollutants from immediately adjacent agricultural land. Vegetated riparian buffers recycle soil organic matter, which elevates soil carbon (C), which upon processing, processes and releases carbon dioxide (CO2). The elevated soil C and seasonally anoxic environments associated with riparian buffers promote denitrification and fermentation, further increasing soil CO2 production.Aim
Against this context, a replicated plot-scale experiment was established at North Wyke, UK, to measure the extent of soil CO2 emissions in permanent pasture served by grass, willow, and woodland riparian buffers, as well as a no-buffer control.Methods
Soil CO2 was measured using the static chamber technique in conjunction with soil and environmental variables between June 2018 and February 2019.Results
Cumulative soil CO2 fluxes were in the descending order: woodland riparian buffer; 11,927.8 ± 1987.9 kg CO2 ha–1 > no-buffer control; 11,101.3 ± 3700.4 kg CO2 ha–1 > grass riparian buffer; 10,826.4 ± 2551.8 kg CO2 ha–1 > upslope pasture; 10,554.6 ± 879.5 kg CO2 ha–1 > willow riparian buffer; 9294.9 ± 1549.2 5 kg CO2 ha–1. There was, however, no evidence of significant differences among all treatments of the current study.Conclusions
Despite the lack of significant differences, the results from our short-term study show that the woodland riparian buffer had relatively larger soil CO2 emissions than the remainder of the other riparian buffers and the upslope pasture it serves. Our short-term findings may be useful in developing soil CO2 mitigation strategies through careful selection of riparian buffer vegetation and may be useful in calibrating mechanistic models for simulating such emissions from similar agro systems. 相似文献23.
Agroforestry Systems - Conspicuous trees and other perennial plants in smallholders’ farms have been acknowledged for their biodiversity conservation values. Impacts of agroforestry... 相似文献
24.
Impact of simulated erosion on the abundance and activity of indigenous vesicular-arbuscular mycorrhizal endophytes in an Oxisol 总被引:1,自引:0,他引:1
M. Habte 《Biology and Fertility of Soils》1989,7(2):164-167
Summary The influence of simulated erosion on the abundance and activity of indigenous vesiculararbuscular mycorrhizal (VAM) populations was evaluated in an Oxisol. Surface-soil losses in excess of 7.5 cm were generally associated with significant decreases in the numbers of total and active VAM propagules and in the symbiotic effectiveness of the active propagules. Surface-soil removal not exceeding 7.5 cm was associated with decreased propagule abundance without adverse effects on VAM colonization of roots and symbiotic effectiveness of the fungi. The extent of VAM colonization of roots and the degree of symbiotic effectiveness observed at this level of simulated erosion were significantly higher than those observed in the soil not subjected to simulated erosion. This stimulation is attributed to the removal of antagonistic biotic factors as the top 7.5 cm of soil was removed. It is concluded that propagules lost during erosional soil losses must be replaced before legumes grown on relatively highly weathered and severely eroded tropical soils could appreciably benefit from the VAM symbiosis.Hawaii Institute of Tropical Agriculture and Human Resources Journal Series No. 3234 相似文献
25.
Growth performance and TOR pathway gene expression of juvenile blunt snout bream,Megalobrama amblycephala,fed with diets replacing fish meal with cottonseed meal 下载免费PDF全文
Qun‐Lan Zhou Habte‐Michael Habte‐Tsion Xianping Ge Bo Liu Jun Xie Mingchun Ren Linghong Miao Liangkun Pan 《Aquaculture Research》2017,48(7):3693-3704
A 16‐week feeding trial was conducted to assess the effects of replacing fish meal (FM) with cottonseed meal (CM) on the growth performance, feed utilization, plasma biochemical composition and target of rapamycin (TOR) pathway gene expression of juvenile blunt snout bream (Megalobrama amblycephala). Five isonitrogenous (36% crude protein) and isoenergetic (16 MJ kg?1) diets with graded replacing levels of CM (replacing 0, 25, 50, 75 and 100% FM with CM) and similar lysine and methionine concentrations were fed to triplicate groups of fish. Results revealed that specific growth rate (SGR), feed intake and protein efficiency ratio (PER) of group fed with diets replacing FM with CM up to 50% were significantly higher than others (P < 0.05). However, final body weight and feed conversion ratio (FCR) remained similar up to 25% and thereafter significantly decreased and increased, respectively, as the replacement level increased (P < 0.05). Replacement levels significantly decreased hepatosomatic index and viscerosomatic index (P < 0.05), but did not significantly affect condition factor and whole body compositions. Free gossypol mainly accumulated in liver and significantly increased in diets CM75 and CM100 than CM0 (P < 0.05). Replacement significantly influenced plasma urea contents (P < 0.05). Meanwhile, increasing replacement of FM with CM in diets increased insulin‐like growth factor I (IGF‐1) gene expression in liver of blunt snout bream. Target of rapamycin (TOR) gene expression in diet CM100 was significantly lower than that in diets CM0 and CM75, while the eukaryotic translation initiation factor 4E‐binding protein 2 (4E‐BP2) gene expression was not affected by the replacement level of CM in diets. Therefore, based on final body weight and FCR, it suggested that up to 25% of FM (150 g kg?1 in basal diet) could be replaced by CM in diets, which was 112.5 g kg?1 FM and 192.9 g kg?1 CM, for juvenile blunt snout bream. 相似文献
26.
An eight‐week feeding trial was conducted to determine the dietary histidine requirement of juvenile blunt snout bream. The results showed that final body weight, weight gain rate and specific growth rate significantly increased with increasing dietary histidine levels up to 9.9 g/kg (p < .05) and decreased gradually thereafter, while feed conversion ratio showed a converse trend. The survival rate, condition factor, viscerosomatic and hepatosomatic index were not significantly affected by the graded dietary histidine levels (p > .05). About 9.9 g/kg dietary histidine level significantly improved whole‐body protein and lowered moisture content. The contents of plasma total protein, cholesterol, urea and triglyceride levels were not significantly affected by dietary histidine levels. About 9.9 g/kg dietary histidine level significantly upregulated target of rapamycin and insulin‐like growth factor mRNA levels (p < .05), and 12.1 g/kg and 14.2 g/kg dietary histidine levels significantly upregulated eukaryotic translation initiation factor 4E‐binding protein 2 and ribosomal protein S6 kinase‐polypeptide 1 mRNA levels (p < .05). Based on second‐degree polynomial regression analysis of weight gain rate, and specific growth rate against dietary histidine levels, the dietary histidine requirement for juvenile blunt snout bream was estimated to be 11.2 g/kg of diet, corresponding to 36.1 g/kg of dietary protein. 相似文献
27.
28.
Major causes of mastitis and associated risk factors in smallholder dairy farms in and around Hawassa, Southern Ethiopia 总被引:1,自引:1,他引:0
Abera M Habte T Aragaw K Asmare K Sheferaw D 《Tropical animal health and production》2012,44(6):1175-1179
A cross-sectional study was carried out from October 2008 to May 2009 in smallholder dairy farms in and around Hawassa to estimate the prevalence of mastitis, to isolate and characterize major bacterial pathogens, and to identify possible associated factors. The study involved a total of 201 milking cows randomly drawn from smallholder farms. The prevalence of clinical and subclinical mastitis was determined through clinical examination of the udder and using mastitis indicator paper (Bovivet indicator paper, Kruuse, Denmark). The prevalence of mastitis at cow and quarter level was 30.3 (61/201) and 10.3 (79/766), respectively. Subclinical mastitis was 25.4% and 5.0% was clinical. Stage of lactation significantly affected (P < 0.05) the prevalence of mastitis, with the highest prevalence observed in the late stage of lactation (41.3%) as compared to early (25.0%) and mid (22.1%) stages of lactation. Floor type and bedding had association (P < 0.05) with mastitis prevalence. Cows housed in concrete-floored houses had lower prevalence (19.0%) of mastitis compared to cows kept in soil-floored houses (47.6%). Mastitis prevalence was low in farms which do not use bedding (23.5%) as compared to farms using hay/straw bedding (37.4%). However, age, parity, and history of mastitis had no association (P > 0.05) on the prevalence of mastitis. The pathogens isolated from mastitic cows were Staphylococcus aureus (48.6%), other staphylococci species (15.7%), Streptococcus agalactiae (11.4%), other streptococci (17.1%), Bacillus species (2.9%), and coliforms (Escherichia coli and Klebsiella species) (4.3%). Strict hygienic measure of housing and bedding should be considered, in reducing the prevalence of mastitis. 相似文献
29.
30.
Two experiments were undertaken to determine the degree of mycorrhizal dependency of pejibaye (Bactris gasipaes, Palmae) seedling progenies from two Amazonian (Pampa Hermosa; Putumayo) and one Central American (Guatuso) land races. Plants were grown in subsurface samples of either an Oxisol (the Amazonian progenies) or an Ultisol, with or without inoculation with the vesicular‐arbuscular mycorrhizae fungus (VAMF) Glomus aggregatum, at three concentrations of soil solution phosphorous (P). VAMF inoculation enhanced leaf phosphorus (P) concentration and dry matter accumulation at the intermediate soil P concentration in all progenies. Dry matter accumulation was enhanced by 17%, 54%, and 64% in the Pampa Hermosa, Putumayo, and Guatuso progenies, respectively. They are therefore classified as being marginally (Pampa Hermosa) or highly dependent. This infra‐specific genetic variation with respect to mycorrhizal dependency merits further study for possible exploitation in plant improvement for sustainable agriculture. 相似文献