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1.
Inorganic fertilizer NPK (nitrogen, phosphorus and potassium) (S) 25:5:5:5 is generally recommended for optimum yield and quality of tea (Camellia sinensis). Non-judicious use of this inorganic fertilizer however acidifies the soils and pollutes the environment. Integrated soil fertility management (ISFM) which involves the combined use of organic and inorganic fertilizer is recommended for improved crop yield and soil health. An experiment was carried out to determine the effect of enriching cattle manure with different ratios of inorganic fertilizers (OM: NPKS at ratios 1:2 and 1:4), and rates on soil nutrient status, nitrogen uptake and yield of tea in the east of Rift Valley, Kenya. Enriching manures and organic manure up to a rate of 150 kg N/ha increased the level of P mature leaf. A higher N and K level in the mature leaf was observed when NPKS was applied at higher rates. In the soil, fertilizer rate up to 150 kg N/ha showed higher pH and K where organic manure and enriched manures were applied while NPKS treatment showed higher P content throughout the soil depths. Enriching organic manures with inorganic fertilizers increased yield significantly. 相似文献
2.
适配体的研究进程与思考* 总被引:1,自引:0,他引:1
适配体(aptamer)是指利用指数富集的配体系统进化(SELEX)技术,从人工合成的寡核苷酸文库中筛选获得的能够与靶分子特异结合的短单链DNA和RNA分子。筛选得到的适配体可以与DNA,RNA,蛋白质或其它靶分子结合,影响这些靶分子的性质,从而起到改变与靶分子相关的生物学功能的效果。而且研究发现,适配体在与靶分子相互作用时,不仅序列,它们所形成的三维结构也尤其重要。同时,适配体在生物医药研究方面显示出广阔的应用前景。介绍了适配体的发展历程,以及一些典型适配体的生物学功效。提出了RNA适配体三维结构在与靶分子进行相互作用时可能发挥重要作用,以期为RNA适配体的筛选提供理论思考。 相似文献
3.
适配体(aptamer)是指利用指数富集的配体系统进化(SELEX)技术,从人工合成的寡核苷酸文库中筛选获得的能够与靶分子特异结合的短单链DNA和RNA分子。筛选得到的适配体可以与DNA,RNA,蛋白质或其它靶分子结合,影响这些靶分子的性质,从而起到改变与靶分子相关的生物学功能的效果。而且研究发现,适配体在与靶分子相互作用时,不仅序列,它们所形成的三维结构也尤其重要。同时,适配体在生物医药研究方面显示出广阔的应用前景。介绍了适配体的发展历程,以及一些典型适配体的生物学功效。提出了RNA适配体三维结构在与靶分子进行相互作用时可能发挥重要作用,以期为RNA适配体的筛选提供理论思考。 相似文献
4.
In vitro Selection of DNA Aptamers and Fluorescence-Based Recognition for Rapid Detection Listeria monocytogenes
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LIU Guo-qing LIAN Ying-qi GAO Chao YU Xiao-feng ZHU Ming ZONG Kai CHEN Xuejiao 《农业科学学报》2014,13(5):1121-1129
Aptamers are specific nucleic acid sequences that can bind to a wide range of nucleic acid and non-nucleic acid targets with high affinity and specificity. Nucleic acid aptamers are selected in vitro from single stranded DNA or RNA ligands containing random sequences of up to a few hundred nucleotides. Systematic evolution of ligands by exponential enrichment (SELEX) was used to select and PCR amplify DNA sequences (aptamers) capable of binding to and detecting Listeria monocytogenes, one of the major food-borne pathogens. A simplified affinity separation approach was employed, in which L. monocytogenes in exponential (log) phase of growth was used as the separation target. A fluorescently-labeled aptamer assay scheme was devised for detecting L. monocytogenes. This report described a novel approach to the detection of L. monocytogenes using DNA aptamers. Aptamers were developed by nine rounds of SELEX. A high affinity aptamer was successfully selected from the initial random DNA pool, and its secondary structure was also investigated. One of aptamers named e01 with the highest affinity was further tested in aptamer-peroxidase and aptamer-fluorescence staining protocols. This study has proved the principle that the whole-cell SELEX could be a promising technique to design aptamer-based molecular probes for dectection of pathogenic microorganisms without tedious isolation and purification of complex markers or targets. 相似文献
5.
葡萄染色体核型及带型研究初报 总被引:1,自引:0,他引:1
采用F-BSG法制备染色体标本,对野生莆萄和栽培品种白香蕉染色体核型和Giemsa带型进行了分析,二者在核型上基本相似,说明亲缘关系相近,但在进化过程中栽培葡萄品种核型有不对称的趋势。 相似文献
6.
Although there seems to be a regular relation of protein change versus time via an exponential equation of the form ID =e(kt), nevertheless, examination of the data indicates that such an exponential fit may be premature. Two other models, ID = kt + b and ID = bt(k) + c represent better fits. Without better data none of the models appears convincing. 相似文献
7.
SELEX技术筛选毒死蜱单链DNA适体 总被引:1,自引:0,他引:1
试验旨在利用SELEX技术体外筛选毒死蜱的特异性适体。体外合成全长为91 nt的ssDNA文库,以链亲和素修饰的凝胶为载体、毒死蜱为靶分子进行SELEX(配体指数增强系统进化技术)筛选。利用荧光标记法测定适体的筛选效率、亲和力和特异性,通过MFOLD分析软件对亲和力较高的适体进行二级结构预测和结合位点分析。结果表明,经过15轮筛选后,DNA文库的筛选效率达到44.00%;最终获得9条ssDNA适体,其中适体N23对毒死蜱具有最高的亲和力,其结合活性显著高于N23与水胺硫磷、丙溴磷、氧化乐果的结合活性;二级结构表明茎环结构可能是毒死蜱与适体相互作用的结构基础。 相似文献
8.
The objective of this study was to evaluate the effects of elemental sulphur (S) and farmyard manure on soil pH, EC and N, S, P concentrations of tomato grown in a calcareous sandy loam soil. For this purpose, a pot experiment was conducted in greenhouse conditions. Sulphur was applied at 0, 50, 100, 150, 200, 400 mg kg~ and farmyard manure at 0, 3 ton da^-1 to the soil. Three weeks after applications, tomato seedlings were planted and 8 weeks later, the plants were harvested to determine N, S, P concentrations and dry matter yield. Soil pH and EC were determined in the soil samples taken at 3 different periods. Effects of sulphur and farmyard manure applications were not significant on N, P concentrations and dry matter yield of tomato plant. S concentration of tomato plant was increased by sulphur alone. Soil pH was decreased and soil EC was increased in both 2^nd and 3^rd soil sampling period by the sulphur applications. As a result of farmyard manure application, soil pH decreased in the 2^nd soil sampling period but increased in the 3^rd soil sampling period. Also, soil EC was significantly increased in 1^st and 3^rd soil sampling period. Farmyard manure had no significant effect on S supply to tomato plant. The N:S ratio of tomato plant was decreased by sulphur alone. However, the sulphur with farmyard manure applications decreased N:S ratio in lesser extend compared to the S applications. 相似文献
9.
Using scanning electron microscopy, we investigated the distribution of the trichoid, basiconic, and coeloconic sensilla on the antennae of the diamondback moth (DBM;Plutella xylostella). The trichoid sensilla were the most abundant sensory organ, and the male moth antennae host signiifcantly more trichoid sensilla than female moth antennae. Conversely, basiconic and coeloconic sensilla were found more frequently on female than on male antennae. We performed experiments with various degrees of antennal ablation and demonstrated that DBM antennae played a key role in the control of mating and oviposition. We found that neither oviposition preference nor mating behaviors changed signiifcantly when less than 1/4 of both antennae were removed. However, there was a signiifcant behavioral change when the antennae were ablated by more than half. As the length of the antenna was shortened, the successful mating rate decreased and mating peak was delayed. An otherwise consistent host preference for oviposition was eliminated when both antennae were completely removed. Furthermore, we found that the number of trichoid sensilla was positively correlated with mating rate and oviposition preference. However, the numbers of basiconic and coeloconic sensilla were not correlated with mating rate and mating peak, but highly correlated with oviposition preference. Taken together, our results indicate that antennal sensory information plays a critical role in the mating and oviposition behaviors of this economically important pest. 相似文献
10.
Rinat Ismagilovich Ibragimov ;Ildar Salimyanovich Mardanshin ;Galina Vasilyevna Benkovskaya ;Maksim Borisovich Udalov ;Irina Andreevna Shpirnaya ;Vyacheslav Olegovich Tsvetkov 《农业科学与技术》2014,(4):331-341
In field and laboratory conditions the reproductive potential (survival at different stages of development) of the Colorado potato beetle has been measured, the dependence of the parameters of insects fertility on varietal features of the feed has been investigated, the food activity of the representatives of insects from four areas of the Southern Urals has been measured, the intensity and time of hypersensitivity reactions on potato leaves has been defined. In laboratory experiments, the level of activity of hydrolytic enzymes in insects and the level of activity of these enzymes inhibitors in the leaves of three potato varieties differing in their resistance to the Colorado potato beetle have been determined. The results show that the insects-representatives of different samples have different food activity in relation to different potato varieties. High mortality rates were revealed at feeding with leaves of potato of the Bashkir variety characterized by a high level of hydrolases inhibitors and relatively rapid development of necrotic reactions after the appearance of eggs laying on the leaves. We suppose that the neerogenetic barrier appearing in the form of necrosis is the major cause of the fetal mortality of insects. The level of the content of inhibitors inactivating larvae digestive enzymes affects the survival of insects at postembryonic stages. The speed of the necrosis emergence, the level of activity of digestive enzymes inhibitors in potato can be considered as criteria for the selection of breeding material for resistance to the Colorado potato beetle. 相似文献
11.
The results of the three-year researches which had the purpose to establish an optimum depth of seeding at sowing and rational norm of seeding of red beetroot seeds at under-winter sowing in conditions of mid-loamy typical grey soils of the central climatic zone of Uzbekistan are stated in article. The researches were spent at statement of field experiences in quadruple frequency with the area of a registration allotment 10 M^-1. Crops were carried out in the first decade of December against mulching surfaces of ridges by humus and without mulching. Crops were carried out on ridges in width of 70 sm tape-two-lined with distance between tapes of 50 sm, between lines-20 sm and distance between plants in a line of 12-13 sm, at density of standing of 228-230 thousand plants/hectares. Experiences were spent with zoned in Uzbekistan multi-seedling grade of a red beetroot "Bordo 237". Experiences were accompanied by phenological supervision, biometric accounts, the account of field germination of seeds, density of standing of plants and definition of size and quality of a crop. Results of researches were exposed to the statistical analysis by a dispersive method. It has been revealed that at under-winter sowing of a red beetroot the effective way providing acceleration of shoots occurrence, formations of high-grade density of standing and increase of productivity of root crops is mulching the surfaces of ridges by humus. It is defined that optimum depth of seeding at sowing both at application of mulching and without it is the depth of seeding 4 sm. It is established that the most rational norm of seeding of the seeds, providing high-grade density of standing, is at cultivation with application of mulching 8 kg/ha, and at cultivation without mulching 8-10 kg/ha. Application of mulching the surfaces of ridges by humus, depths of seeding of 4 sm and norms of seeding of seeds of 8-10 kg/ha in conditions of under-winter sowing in comparison with cultivation without mulching and depth of seeding 2 sm and norms of seeding of 6 kg/ha provides an acceleration of receipt of fresh production of a red beetroot for 12-14 days and considerably raises root crops productivity. Application of agro receptions improved by us is the important reserve of acceleration of receipt of red beetroot early production and increase of its manufacture. 相似文献
12.
The effects of different tillage systems and poultry manure on soil physical properties, performance and nutrients in sorghum were studied for three years at Owo, southwest Nigeria. There was factorial combinations of herbicide-based zero tillage (ZT), manual clearing (MC), disc ploughing (P), ploughing plus harrowing (P+H) and ploughing plus double harrowing (P+2H), and two rates of poultry manure at 0 and 7.5 Mg ha^-1. Herbicide-based zero tillage and manual clearing reduced soil temperature and conserved more water than mechanized tillage techniques. Poultry manure reduced soil bulk density and temperature and increased soil water and porosity. There was a percentage decrease of leaf N, P, K, Ca and Mg concentrations, plant height, leaf area, stem girth, root dry weight, dry matter and grain yield in ascending order for herbicide-based zero tillage, manual clearing, ploughing, ploughing plus harrowing and ploughing plus double harrowing while percentage increases were recorded in a descending order for all the various combinations of tillage with poultry manure in that order. Poultry manure in combination with tillage increased dry matter and grain yield by 33.1 and 39.5%, respectively in comparison with tillage only. The manure-zero tillage methods increased dry matter and grain yield by 8% and 15%, respectively when compared with manure-mechanized tillage methods. Zero tillage or manual clearing in combination with 7.5 Mg ha^-1 poultry manure was most suitable for sorghum cultivation. 相似文献
13.
The responses of five inter-specific lowland rice cultivars (NERICA-L-19, NERICA-L-20, NERICA-L-41, NERICA-L-42, and NERICA-L-60) and four improved Oryza sativa cultivars (FKR 19, BW 348-1, WITA 4, and SIPI 6923033) to levels of phosphorus and nitrogen fertilization were compared on a Typic Natrustalfat Kadawa in the Nigerian Sudan Savanna in 2006 and 2007 The responses of the NERICA-L eultivars to N and P fertilization were similar to the O. sativa cultivars. In a dry year (2007), the NERICA-L cultivars gave higher yields than O. sativa cultivars. Phosphorus level did not significantly affect crop physiology, yield, and yield components of all the cultivars. Pooled across cultivars, N and P levels, days to panicle initiation, mid-flowering and maturity were, respectively delayed by 17.0, 15.6 and 6.4 days in 2007 compared to 2006. NERICA-L-42 and NERICA-L-41 were the most stable, exhibiting the least difference in duration to maturity between the two years (3.5 and 4.4 days, respectively), and could therefore be more adapted to rain-fed environments prone to frequent droughts. Increasing N levels from 0 to 120 kg hal produced yield increments of 62.9 and 37.2% in 2006 and 2007, respectively. Cultivars FKR 19 and WITA 4 gave higher yields in 2006 (3940 and 3542 kg ha^-1, respectively), while in 2007, NERICA-L-42, NERICA-L^-19 and NERICA-L-20 ranked among the highest in grain yield (3935, 3807 and 3726 kg hal, respectively) and could be recommended to resource-poor farmers. a 相似文献
14.
The residual effect of organic and mineral fertilizers on selected chemical properties of an Alfisol in the long term soil fertility trial established in 1950 at Samaru, Nigerian savanna was assessed. The trial was left fallow for fourteen years due to lack of funds. Topsoil was collected from plots that received three levels of cow dung (D), nitrogen (N) and phosphorus (P) in all possible combinations. The soils were analyzed for selected chemical properties. Except for significant effect of applied P on available P, sole application of cow dung, N or P had no significant effect on all the measured soil properties. The interaction of D and P significantly affected the mean values of exchangeable Ca, Mg, K and ECEC in the range of 1.12-1.96, 0.62-1.11, 0.37-0.64 and 2.82-4.11 cmol/kg respectively. The most important results were the ability of the plot that received neither D nor P to significantly increase these parameters than the plots that received only one of the treatments. The results show that the fallow period has changed the effects of application of organic and mineral fertilizers on the soil chemical properties under continuous cultivation by modifying them towards those of a native savanna Alfisol. 相似文献
15.
Yihunie Hibstie Asres ;Ashok Kumar Chaubey ;Awoke Taddesse Hailu ;Dilbetigle Assefa Mamo 《农业科学与技术》2014,(4):342-352
Farmers may not be conscious for their farmland's nutrients, soil organic matter, water and air because they simply concerned only for their labor availability and soil fertility losses. The composition and proportion of these components greatly influence soil physical properties, including texture, structure and porosity, the fraction of pore space in a soil. The soil of this farmland must be able to supply adequate amount of plant nutrients, in forms which can be absorbed by the crop, within its lifespan. Deficiencies or imbalances in the supply of any of essential elements can compromise growth, affecting root development, cell division, crop quality, crop yield and resistance to disease and drought. This study was conducted to fill this knowledge gap in order to develop economically vital and environmentally accepted nutrient management strategies for the use of soils in agricultural lands. The objective of this study is to assess the elemental contents and concentration of soil samples collected from farmlands of "Yebrage" using neutron activation analysis (NAA) techniques regardless of oxidation state, chemical form or physical locations. NAA is used to determine the elemental composition and concentrations present in a soil. The macro/micronutrient and organic matter deficiencies have been verified in agricultural soils through increased use of soil testing and plant analysis. The challenge for agriculture over the coming decades will meet the world's increasing demands for food in a sustainable way. Current issues and future challenges point out that as long as agriculture remains a soil based industry, major decreases in productivity likely to be attained ensuring that plants do not have adequate and balanced supply of nutrients. 相似文献
16.
We represent assessment of the rats control operator's actions, starting from the placement of rat control means (chemical, mechanical and others) in the object territory until the full its elimination and followed by assessment of the probability of rat population recovery. The probability of success is evaluated when using a combination of rat control means. We took into account changes in rat population occurring in different calendar periods of the year. The proposed calculation method can be used in training programs, as well as for the local forecast of releasing objects from rats and rats' re-settling. 相似文献
17.
SHI Bao-kun HUANG Jian-li HU Chao-xing HOU Mao-lin 《中国农业科学(英文版)》2014,(7):1520-1529
It is predicted that the current atmospheric CO2 concentration will be doubled and global mean temperature will increase by 1.5-6°C by the end of this century. Although a number of studies have addressed the separate effects of CO2 and temperature on plant-insect interactions, few have concerned with their combined impacts. In the current study, a factorial experiment was carried out to examine the effect of a doubling CO2 concentration and a 3℃ temperature increase on a complete generation of the brown planthopper (Nilaparvata lugens) on rice (Oryza sativa). Both elevated CO2 and temperature increased rice stem height and biomass of stem parts. Leaf chlorophyll content increased under elevated CO2, but only in ambient temperature treatment. Water content of stem parts was reduced under elevated temperature, but only when coupled with elevated CO2. Elevated CO2 alone increased biomass of root and elevated temperature alone enhanced leaf area and reduced ratio of root to stem parts. Brown planthopper (BPH) nymphal development was accelerated, and weight of and honeydew excretion by the F1 adults was reduced under elevated temperature only. Longevity of brachypterous females was affected by a signiifcant interaction between CO2 and temperature. At elevated temperature, CO2 had no effect on female longevity, but at ambient temperature, the females lived shorter under elevated CO2. Female fecundity was higher at elevated than at ambient temperature and higher at elevated CO2 than at ambient CO2. These results indicate that the combined effects of elevated temperature and CO2 may enhance the brown planthopper population size. 相似文献
18.
Sowing time of wheat in south eastern Australia varies from autumn to early winter, depending on the seasonal 'break'. Wheat yields are often reduced by frost damage at flowering time and by heat-and/or water-stress during grain filling. Selecting suitable varieties for specific sowing times is a complex decision farmers make because these varietal phenology and climate risks have to be assessed together. In order to help farmers make decisions, they need tools that simulate and analyse agronomically-suitable sowing dates (ASSD) for a given variety of wheat. The hypothesis underlining this study is the integration of a wheat phenology model with historical climate data is an effective approach to modelling the ASSD of current varieties used in the wheat growing areas of Southern NSW. The parameters of the wheat phenology model were based on data from five years of field experimentation across 15 sites. Data from four sites were used to examine varietal suitability in relation to sowing time and its associated risks of frost and heat damage. The optimum ASSD for any variety at 72 locations across Southern NSW was investigated. The results showed that there were substantial spatial variations in the ASSD across the target region. ASSD for a late maturing wheat genotype (EGA Gregory) can range from early March to late April, while the earliest acceptable sowing date for an early maturing spring wheat genotype (H46) can range from early to late May. The wide range of spatial variation in the earliest and latest sowing dates, as well as the varied length of sowing opportunities, highlighted the importance of being able to apply a modelling approach which can integrate information on crop phenology with climate risk for a given location. This approach would allow better decision-making on suitable varieties and sowing dates in order to minimise the risk of frost and heat damage affecting crop yield. 相似文献
19.
The quality office is complex and made up of many components such as nutritional quality, appearance, cooking quality and eating quality. The cultivar is one of the main factors that could affect to the grain quality office. The aim of this work was to analyze and compare the cooking quality parameters of six different japonica varieties of rice grown in Spain (Senia, Gleva, Bahia, Maratelli, Guadiamar and Bomba). This work focused on the study of the cooking quality of rice, because it is one of the most important factors related to grain quality in Spain. It was evaluated using five characteristics: amylose content, gel consistency, degree of spreading, gelatinization temperature and pasting parameters. The amylose content ranged from 11.60% to 21.46%, with the Gleva cultivar having the lowest amylose content and with Bomba having the highest. The gel consistency varied between 5.44 cm and 9.81 cm. Regarding the alkali test, the Maratelli cultivar had the highest dispersion and transparency. Maratelli had the lowest gelatinization temperature (61.67±0.08 ℃), and Senia had the highest gelatinization temperature (67.05±0.02 ℃). Finally, the pasting parameters showed significant differences among cultivars with different viscosities. 相似文献
20.
F. Perveen 《农业科学与技术》2011,(1):73-80
Identification of lxodid tick species on livestock in two districts, viz., D.I. Khan and Lakki Marwat of Northern Pakistan were made during the period from March to November 2009 through animals' survey and questionnaire. The main tick species were Amblyomma (14.3%), Boophilus microplus (l 8.5%) and Hyalomma anatolicum and H. dromedarii (67.2%). Out of 3009 collected ticks, the highest number of female (88.7%) and the lowest of males ( l 1.3%) belong to Boophilus; the lowest number of female (92.4%) and the highest of males (77.5%) belong to Amblyomma. However, cows were more susceptible than buffaloes and camels ranked third to ticks infestation. Moreover, cows, buffalos, goats and sheep harbored mixed infestation (had more than one type of ticks), however, camels and donkey harbored single infestation (had only one type of tick). An emerging ethno-veterinary or traditional remedy is poultry keeping for ticks' elimination in Lakki Marwat. The results of this research will be helped in taking appropriate measures to reduce tick infestation and to improve management practices. Hence, it will help to increase farm productivity and farmers income. 相似文献