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Analysis of the behavior of slow releasing nitrogen fertilizers in the rhizosphere soil of agricultural crops is essential for their effective use. This work presents a comparative study of the effects of oxamide and ammonium sulfate as different N sources on the relative mobility of some nutritionally important anions and cations and their relevance to plant growth, root development, and pH distribution pattern in the rhizosphere of wheat (Triticum aestivum cv. Nourin No. 61). Experiment was conducted on a Japanese upland alluvial soil through a rhizobox approach. In the central compartment (CC) of the oxamide and ammonium sulfate treated rhizoboxes, four uncontaminated and homogeneous wheat seedlings germinated on a sterile petridish were grown for nearly two months. During the growing period plant height was recorded weekly. After the growing period, rhizoboxes were dismantled for soil sampling and photography of roots. Soil samples from each compartment of the two rhizoboxes were used for the analysis of CI-, N03 -, SO4 2-, Ca2+, Mg2+, K+, NH4 +-N, N03 --N and measurement of pH. Compared with ammonium sulfate, the distribution of anions and cations from the distant compartments to the central ones over a distance of 3–5 mm along with a better plant growth, high rooting density, and high pH confirmed that oxamide was an efficient nitrogen fertilizer. 相似文献
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Effects of shifting cultivation on biological and biochemical characteristics of soil microorganisms in Khagrachari hill district,Bangladesh 总被引：1，自引：0，他引：1
We collected soil samples from two representative sites at Aatmile of Khagarachari hill district in Chittagong Hill Tracts. One of the sites was under shifting cultivation and the other an adjacent 13-year old teak plantation. Both sites were in the same physiographic condition and same aspect with parable soil type, which enabled us to measure the effects of shifting cultivation on soil micro-flora. We studied soil physico-chemical properties and the biochemical and biological properties of soil microbes. Moisture and organic matter content as well as fungi and bacterial populations, both in surface and subsurface soils, were significantly(p ≤0.001) lower in shifting cultivated soils compared to soils not under shifting cultivation, i.e. the teak plantation site. The most abundant bacteria in surface(0-10 cm) and sub-surface(10-20 cm) soils under shifting cultivation were Pseudomonas diminuta and Shigella, respectively, while in corresponding soil layers of teak plantation, predominant microbes were Bacillus firmus(0-10 cm) and Xanthomonas(10-20 cm). The microbial population differences cannot be explained by soil texture differences because of the textural similarity in soils from the two sites but could be related to the significantly lower moisture and organic matter contents in soils under shifting cultivation. 相似文献
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G Pedrana MH Viotti E Souza D Sloboda GB Martin D Cavestany HH Ortega 《Reproduction in domestic animals》2013,48(5):795-802
Pre‐natal glucocorticoids are used in women at risk of preterm delivery to induce foetal lung maturation. However, glucocorticoids can produce negative outcomes for other tissues such as the reproductive system. We therefore tested the effects of pre‐natal betamethasone on testicular morphology and apoptotic protein immune expression during pre‐ and post‐natal development. Pregnant ewes (n = 42) bearing singleton male foetuses were randomly allocated to receive intramuscular injections of saline or betamethasone (0. 5 mg/kg) at 104, 111 and 118 days of gestation (DG). Testes were collected at 121 and 132 DG, and at 45 and 90 post‐natal days (PD) and subjected to morphometric analysis (volume densities of sex cords and interstitial tissues; sex cord diameter). Immunohistochemistry (% stained area) was used to assess active caspase‐3, Bax, Bcl‐2 and cell‐cycle proteins (PCNA). Compared with control values, betamethasone treatment decreased sex cord diameter at 121 DG, 45 and 90 PD, and sex cord volume at 90 PD. Active caspase‐3 was decreased by betamethasone at 121 DG and 90 PD, but Bax was increased in all betamethasone groups. Bcl‐2 and PCNA decreased in the betamethasone groups at 121 DG and 45 PD, but increased at 132 DG and 90 PD. We conclude that high levels of pre‐natally administered glucocorticoid reduce foetal testicular development, perhaps via changes in the balance between pro‐ and anti‐apoptotic proteins and cell‐cycle proteins. These outcomes could compromise the future spermatogenic potential of male offspring. 相似文献
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Md. Giashuddin Miah Mohammad Mahbub Islam Md. Abiar Rahman Tofayel Ahamed Md. Rafiqul Islam Shibu Jose 《Agroforestry Systems》2018,92(6):1687-1697
A number of traditional and modern agroforestry systems are common in the agricultural landscape of Bangladesh. Jackfruit (Artocarpus heterophyllus Lam.) based agroforestry is one of them and predominantly found in terrace ecosystems. There is an enormous opportunity to improve the system through utilizing available space by growing compatible associated crops. For this, a jackfruit orchard was transformed into a multistoried agroforestry system during the period from 2012 to 2013, where jackfruit trees were kept as overstory, and associated crops, such as papaya and eggplant were grown as middle and lower story crops, respectively. In the improved system, jackfruit yield increased by 32.7% due to fertilizers and irrigation applied for the middle and lower-storied crops. Yields of papaya and eggplant were reduced by 22.8 and 17.4%, respectively, because of competition for both belowground and aboveground resources. For example, light interception by the middle and lower story crops were 55.5 and 30.8%, respectively. However, the total production per unit area (by combining the yields of jackfruit, papaya, and eggplant) in the multistoried agroforestry system was remarkably higher than the monoculture system for the same area due to intensive land use. The benefit–cost ratio and land equivalent ratio for the studied multistoried agroforestry systems were 5.47 and 2.59, respectively. These results suggest that the traditional jackfruit orchard could be transformed to multistoried agroforestry systems for its higher system productivity including higher yield, and increased income that ultimately will improve the livelihood of the farming community. 相似文献
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The aphids Aphis craccivora Koch attack country bean Lablab purpureus L. both in its vegetative and reproductive stages and cause severe damage. To develop an integrated management of aphid powders of black pepper, chili, turmeric, and coriander; oils of mahogany, neem, and eucalyptus; aqueous extracts of neem, basil, and garlic leaves; and water were evaluated in field conditions. The treatments were applied at 7?day intervals and aphid abundance per inflorescence was counted at 24, 48, and 72?h after treatment. All the plant materials reduced aphid abundance and flower infestation, ensuring a higher yield with larger and heavier pods. The neem oil treatment had the lowest abundance of aphid and consequently produced the highest marketable and gross yields. Predatory insects were abundant in the field, but their populations were lower in the treatments than the control. An economic analysis indicated that the highest gross return, net return, adjusted net return, and benefit-cost ratio were obtained from the mahogany oil treatment. The plant materials have insecticidal potential against aphids, and the oils of mahogany and neem showed better performances. 相似文献
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Abstract A survey conducted during 1979–81 in Bangladesh revealed 20 rice diseases, including two viral, two bacterial, 13 fungal, two nematode and one micronutrient deficiency problem. Of these diseases. 16 appeared as major during the period under report. The number of diseases were 17, 16 and 16 during the Boro. Aus and transplant Aman seasons, respectively, with 12 common in all three seasons. Thirteen diseases including bacterial blight, bacterial leaf streak, sheath blight, sheath rot, blast, brown spot, grain spot, stem rot and leaf scald were classified as major; and tungro, bakanae, cercospora leaf spot and zinc‐deficiency were classified as either major or minor, and were common to all regions. Diseases not common in all regions were stack burn, root knot, and ufra classified as major or minor, and false smut, seedling blight. Yellow dwarf and damping off which were always classified as minor. Diseases which were typical for Boro. Aus and transplant Aman seasons were seedling blight and damping off. Yellow dwarf, and false smut respectively. Aus the most humid and warmest season, and the coastal humid areas experienced more major diseases. Seasonal and regional differences in the disease incidence appeared related to agro‐climatic variations. 相似文献
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Irradiation of gaseous carbon disulfide [CS2(g)] at 313 nanometers produces a dark brown aerosol of (CS2)x. Its thermal decomposition products include disulfur (S2), carbon monosulfide (CS), and (CS)x. The photopolymerization process is accompanied by a large mass-independent isotopic fractionation of sulfur (a 5 to 10 per mil sulfur-33 excess and a 61 to 84 per mil sulfur-36 deficit). Excess sulfur-33 has been observed in several classes of meteorites. Photochemical production of (CS2)x may be important in the origin and evolution of cosmochemical environments such as the presolar nebula, meteorites, asteroids, and planetary atmospheres. 相似文献
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Robert T Jones Saskia E Bakker Deborah Stone Sally N Shuttleworth Sam Boundy Caroline McCart Phillip J Daborn Richard H ffrench‐Constant Jean MH van den Elsen 《Pest management science》2010,66(10):1106-1115
BACKGROUND: Overexpression of the cytochrome P450 gene Cyp6g1 confers resistance against DDT and a broad range of other insecticides in Drosophila melanogaster Meig. In the absence of crystal structures of CYP6G1 or complexes with its substrates, structural studies rely on homology modelling and ligand docking to understand P450–substrate interactions. RESULTS: Homology models are presented for CYP6G1, a P450 associated with resistance to DDT and neonicotinoids, and two other enzymes associated with insecticide resistance in D. melanogaster, CYP12D1 and CYP6A2. The models are based on a template of the X‐ray structure of the phylogenetically related human CYP3A4, which is known for its broad substrate specificity. The model of CYP6G1 has a much smaller active site cavity than the template. The cavity is also ‘V’‐shaped and is lined with hydrophobic residues, showing high shape and chemical complementarity with the molecular characteristics of DDT. Comparison of the DDT–CYP6G1 complex and a non‐resistant CYP6A2 homology model implies that tight‐fit recognition of this insecticide is important in CYP6G1. The active site can accommodate differently shaped substrates ranging from imidacloprid to malathion but not the pyrethroids permethrin and cyfluthrin. CONCLUSION: The CYP6G1, CYP12D1 and CYP6A2 homology models can provide a structural insight into insecticide resistance in flies overexpressing P450 enzymes with broad substrate specificities. Copyright © 2010 Society of Chemical Industry 相似文献