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1.
Three goats fitted with cannula were used to provide rumen liquor to investigate the effects of limiting amino acids on rumen fermentation and microbial community in vitro. The removal method was used in the current experiments. Treatments are total essential amino acid (TEAA), His-removal, Lys-removal, Met-removal, and branch chain amino acid (BCAA)-removal. Results indicated that, pH-value ranged between 5.9 and 6.8, with the highest mean value for the group with BCAA-removal (6.54) in the culture. Concentration of NH3-N ranged between 10.99 to 30.51 mg 100 mL-1, with the group of TEAA recording the highest average NH3-N concentration (17.85 mg 100 mL-1). Yields of microbial protein and limiting degree on microbial growth varied with treatments (P < 0.01), and the lowest accrued in treatment with BCAA-removal (0.1389, 0.1772, and 0.3161 mg mL-1 for bacteria, protozoa, and mixed microbes, respectively), compared to the group with TEAA, microbial production of mixed microbes decreased by 44.52%. As for micro-flora, protozoa to bacteria ratio was the lowe st for the group with Lys-removal (89.12%), while the h i ghe st for the group with B CAA-removal (127.60%) (P < 0.01). Furthermore, PCR-SSCP analysis revealed that, microbial profile subjected to substrates within bacteria and protozoa groups. It was therefore concluded that, dietary amino acid influenced both rumen fermentation and microbial characteristics.  相似文献   

2.
 【目的】研究特定氨基酸在人工瘤胃体外培养条件下如何影响瘤胃微生物群系特征及其发酵。【方法】研究中以3只瘘管山羊作为瘤胃液供体,采用底物去除技术,底物设计分别为：全量必需氨基酸组（TEAA）,组氨酸、赖氨酸、蛋氨酸和支链氨基酸（BCAA）的缺省组。【结果】底物对培养液pH均值没有显著性影响,但各组pH值随时间的变化模式有所不同;培养液氨氮浓度较高,在10.99～30.51 mg/100 ml范围变动,各组氨氮浓度随时间的变化模式也有明显的不同;特定氨基酸缺省对微生物蛋白产量限制程度不同,以BCAA缺省对微生物蛋白产量的限制最大,相对于全量组混合微生物蛋白下降了44.52%。研究还发现底物对微生物区系也有一定的影响,原虫与细菌比值以赖氨酸缺省组最低（89.12%）,BCAA缺省组最高（127.60%）（P＜0.01）。另外,微生物的PCR-SSCP图谱显示微生物区系内的种属也因底物变化而发生了改变。【结论】底物氨基酸对瘤胃混合微生物群系及其发酵有一定的影响作用,支链氨基酸是瘤胃混合微生物生长所必需的氨基酸。  相似文献   

3.
Root function in uptake of nutrients and the effect of soil water on the transfer and distribution of NO3^--N in arable soil were studied using summer maize （Zea mays L. var. Shandan 9） as a testing crop. Results showed that root growth and water supply had a significant effect on NO3^--N transfer and made NO3^--N distributed evenly from bulk soil to rhizosphere soil. Under a natural condition with irrigation, the difference of NO3^--N concentration at different distance points from a maize plant was smaller, while obvious difference of NO3^--N concentration was observed under conditions of limited root growth space without irrigation. Whether root growth space was restricted or not, the content of soil NO3^--N decreased gradually from 10 to 0 cm from the plant, being opposite to the root absorbing area in soils. When root-grown space was limited, changes of NO3^--N concentration at different distances from a plant were similar to that of water content in tendency. Results showed that NO3^--N could be transferred as solute to plant root systems with water uptake by plants. However, the transfer and distribution of NH4^--N were not influenced by root growth and soil water supply, being different to NO3^--N.  相似文献   

4.
In a completely randomized block design experiment, 16 ruminally cannulated sheep (40 ± 2.1 kg)fed a 50% concentrate 50% forage diet (DM basis) were given intraruminal doses of powdered Yucca schidigera extract (YSE). Doses of 0 (control), 100, 200, or 300 mg kg-1 diet were given at 8 p.m. and 4 a.m. On 15, 16, and 17 d of the experimental period, ruminal contents were sampled 0, 2, 4, 6, and 8 h after dosing, and blood samples were collected at the end of the experiment (18th and 19th d). Acidity was not affected (P＞0.05) by the addition of YSE. Compared with the control, ruminal propionate concentration was increased by 29.4 and 29.8% (P＞0.05) and the acetic acid concentration was decreased by 15.1 and 19.8% (P＞0.05) at 4 and 6 h after YSE (300 mg kg-1) dosing, respectively. Ruminal ammonia concentration in the first 2 h after feeding was higher (P＜0.05) in the sheep that did not receive YSE (increased by 17.57 mg 100 mL-1) than in those that received 200 mg kg-1 (increased by 6.77 mg 100 mL-1) or 300 mg kg-1 (increased by 6.50 mg 100 mL-1) YSE. Protozoan populations in the rumen were lower (P ＜ 0.05) in the animals that received 300 mg kg-1 of YSE compared with the control. All serum parameters of the four groups were in the normal range and were similar among the treatment groups (P＞0.05), after being fed for 19 d with different doses of YSE. The effect of YSE on ruminal ammonia concentration likely resulted from a decreased concentration of protozoan populations and, presumably, from ammonia binding by YSE.  相似文献   

5.
Active oxygen quantum yield, insecticidal activities and stability of diphenylthiophene were studied for the first time. The results showed that maximum diphenylthiophene absorbency variety was 0.438 after irradiation for 280 min and that of α-terthienyl (α-T) was 0.480 after irradiation for 200 min with UV. LC50 values ofdiphenylthiophene and α-T against 3rd instar larvae of Aedes albopictus were 9.18 × 10-3 and 9.69 × 10-4 μg mL-1 when treated for 24 h, respectively. LC50 values of the two chemicals against the 3rd instar larvae of Plutella xylostella were 267.87 and 222.22 μg mL-1 when treated for 24 h, respectively. The half lives of diphenylthiophene and α-T in methanol were 113.62 and 10.65 h. Difference between quantum yield of diphenylthiophene and α-T was not significant and they all possessed high toxicity to Aedes albopictus and Plutella xylostella, but diphenylthiophene was more stable than α-T. It could be concluded that diphenylthiophene has overcome the deficiency of photoactivated insecticides which degraded quickly in the environment and could not be applied on the field. Diphenylthiophene could kill the insects and accelerate the degradation rate of triazophos. The benefits of diphenylthiophene can be further exploited and applied on the field.  相似文献   

6.
A long-term （1982-2001） field experiment was conducted in a calcareous soil under wheat （Triticum aestivum L.）-wheat （Triticum aestivum L.）-maize （Zea mays L.） rotation system at Zhangye, Gansu Province, China to determine the effects of long-term fertilization on crop yield, nutrients interactions, content and accumulation of nitrate-N in soil profiles. Twenty- four plots in a split-plot factorial with a combination of eight treatments （from nitrogen （N）, phosphorus （P）, potassium （K） and farmyard manure （M） applications） and 3 replications were selected. Main treatments were M and without M, and the sub-treatments were no-fertilizer （CK）, N, NP and NPK. When P and K fertilizers were part of treatments, their ratio to N was 1N：0.22P：0.42K. All M, P and K fertilizers were applied as the basal dressing. The grain yield was harvested each experimental period and straw yield for the period from 1988 to 1997. After crop harvest in 2000, the soil was sampled from the 0-20, 20-60, 60-100, 100-140 and 140-180 cm depths to determine NO3^--N content. Maize yield of CK in 2000 was only 28.2% of that in 1984, and wheat in 2001 was 25.7% of that observed in 1982. Average impact of fertilizers on grain yield decreased in the order of N 〉 M 〉 P 〉 K. Yield response to N and P fertilizers increased with progress of the experiment. The impact of K fertilizer showed no increase in grain yield during the initial 6 years （1982-1987）, moderate increase in the next 5 years （1988-1992）, and considerable increase in the last 9 years （1993-2001）. The straw yield trend was similar to grain yield. Accumulation and distribution of NO3^--N in soil was significantly affected by annual fertilizations. Mineral fertilizers （NP and NPK） led to NO3^- -N accumulation in most subsoil layers, with major impact in the 20-140 cm depth. The combination of mineral fertilizers and farmyard manure （MNP and MNPK） reduced soil NO3^--N accumulation in comparison to mineral fertilizers, It can be argued that long-term fertilization significantly enhanced grain and straw yield in this rotation scheme. The findings of this research suggest that it is important to balance application of mineral fertilizers and farmyard manure in order to protect soil and underground water from potential NO3^--N pollution while sustaining high productivity in the oasis agro-ecosystem.  相似文献   

7.
The digestive tract of termite(Microcerotermes diversus) contains a variety of lignocellulose-degrading bacteria with exocellulases enzyme activity, not found in the rumen, which could potentially improve fiber degradation in the rumen. The objectives of the current study were to determine the effect of inoculation of rumen fluid(RF) with three species of bacteria isolated from termite digestive tract, Bacillus licheniformis, Ochrobactrum intermedium, and Microbacterium paludicola, on in vitro gas production(IVGP), fermentation parameters, nutrient disappearance, microbial populations, and hydrolytic enzyme activities with fibrous wheat straw(WS) and date leaf(DL) as incubation substrate. Inoculation of RF with either of three termite bacteria increased(P0.05) ammonia-N concentration compared with the control group(free of termite gut bacteria). Termite bacteria inoculation had no effect(P0.05) on gas production characteristics, dry matter, organic matter and neutral detergent fiber disappearance, pH, and concentration and composition of volatile fatty acids. Population of proteolytic bacteria and protozoa, but not cellulolytic bacteria, were increased(P0.05) when RF was inoculated with termite bacteria with both WS and DL substrates. Inoculation of RF with termite bacteria increased protease activity, while activities of carboxymethyl-cellulase, microcrystalline-cellulase, α-amylase and filter paper degrading activity remained unchanged(P0.05). Overall, the results of this study indicated that transferring lignocellulose-degrading bacteria, isolated from digestive tract of termite, to rumen liquid increased protozoa and proteolytic bacteria population and consequently increased protease activity and ammonia-N concentration in vitro, however, no effect on fermentation and fiber degradation parameters were detected. These results suggest that the termite bacteria might be rapidly lysed by the rumen microbes before beneficial effects on the rumen fermentation process could occur.  相似文献   

8.
王洪荣  张洁 《中国农业科学》2011,44(5):1071-1076
 【目的】研究日粮中不同碳水化合物结构对山羊瘤胃发酵和微生物氨基酸组成的影响,为回答“瘤胃微生物的氨基酸组成是否恒定？”这一国际学术界仍有争论的问题提供理论依据。【方法】选用4头装有永久性瘤胃瘘管的徐淮山羊,采用4×4拉丁方试验设计,以玉米、豆粕、稻草为基础日粮,研究不同非结构性碳水化合物与结构性碳水化合物之比(NSC/SC)处理(A：0.33、B：0.63、C：1.17及D：2.18)对pH、NH3-N、VFA浓度及瘤胃微生物氨基酸组成的影响。【结果】随着日粮中NSC/SC的升高,瘤胃pH显著降低(P＜0.05),NH3-N浓度显著升高(P＜0.05),乙酸的摩尔百分比和乙酸/丙酸的比值随日粮中NSC/SC的升高而显著降低(P＜0.05)。不同NSC/SC的日粮下的细菌氨基酸含量中,天冬氨酸、丝氨酸、甘氨酸、缬氨酸、蛋氨酸、亮氨酸、苯丙氨酸、组氨酸、精氨酸、脯氨酸含量都存在显著差异或极显著差异(P＜0.05),原虫氨基酸中天冬氨酸、丙氨酸、亮氨酸、苯丙氨酸、赖氨酸、组氨酸、脯氨酸产生了显著变化(P＜0.05)。【结论】瘤胃微生物氨基酸组成会受到日粮中NSC/SC比例的影响。  相似文献   

9.
With the bioguided fractionation of the ethanol extracts from the leaves of Momordica charantia, we obtained two most active compounds against the feeding of the diamondback moth, Plutella xylostella larvae. The antifeedant activity of momordicine Ⅰ and momordicine Ⅱ against the second and the third instar larvae of Plutella xylostella were tested using leaf discs of cabbage in the laboratory. The results showed that momordicin Ⅰ and momordicin Ⅱ had significant antifeedant activity on the larvae of P. xylostella, and momordicin Ⅱ was more active than momordicin Ⅰ. The concentrations for 50% antifeedant effects （AFC50） of momordicin Ⅱ against the second and the third instar larvae of P. xylostella were 76.69 and 116.24μg mL^-1, whereas that of momordicin I was 144.08 and 168.42μg mL^-1, respectively. In addition, momordicin Ⅰ and momordicin Ⅱ had significant inhibitive effect on the rate of weight gain and survival of P. xylostella larvae.  相似文献   

10.
The isolates of Phytophthora infestans on tomato in the Guangxi Zhuang Autonomous Region, China, were determined for the sensitivities to metalaxyl, cymoxanil and dimethomorph to give the basic information for integrating disease management. Sensitivities were tested by measuring the radial growth on agar medium amended with fungicide, compared with the floating-leaf-disk method. 239 isolates were collected from eight tomato growing areas during 2000-2006. The testing results indicated that the frequencies of sensitive, intermediate, and resistant isolates to metalaxyl were 42.26, 35.98, and 23.53%, respectively. Variations in sensitivities amongst isolates from different areas or different years were very high for metalaxyl. All isolates from Tianlin and Wuxuan were sensitive to metalaxyl, but the metalaxyl-resistant isolates predominated in Tianyang, with the frequency of 51.35%. The EC50 values of certain isolates from Tianyang were higher than 500 μg·mL^-1 and their resistance levels were over 100 000 folds. Cymoxanil has been used for nearly 10 years in Guangxi, and dimethomorph has been used for 5-6 years. However, there was no decrease in sensitivity of P. infestans populations and the sensitivities of the pathogen were nearly normally distributed. Hence, their mean ECs0 value [cymoxanil （0.1647 ±0.0255） μg·mL^-1, dimethomorph （0.0970 ± 0.0052） μg·mL^-1 could be used as the baseline sensitivities for monitoring the field resistance development. The comparison with the floating-leaf-disk method indicates that both the techniques provided equivalent results. These studies suggested that metalaxyl can be continuously applied in Tianlin, Wuxuan, and Nanning due to the resistant isolates that have not been found, while for those areas with resistant isolate, the use of metalaxyl should be reduced or alternated, and cymoxanil or dimethomorph was recommended for controlling late blight disease of tomato.  相似文献   

11.
王洪荣  秦韬  王超 《中国农业科学》2014,47(24):4904-4914
【目的】青蒿素是天然青蒿属植物的提取物,它很早就在中国传统中药中被用作抗疟疾、抗肿瘤和驱虫等药物。为探讨青蒿素对反刍动物瘤胃发酵、瘤胃内环境及其瘤胃微生物蛋白质循环的影响,确定青蒿素的对瘤胃发酵调控的效果和适宜添加量,为青蒿素作为一种新的瘤胃调控剂在反刍动物生产中应用提供依据。【方法】采用4只带有瘤胃瘘管的徐淮白山羊为试验动物,饲喂以玉米、豆粕和羊草为主组成的基础日粮,在基础日粮中分别添加占日粮干物质0,0.2%,0.4%和0.6%的青蒿素,进行4×4拉丁方设计试验,研究对山羊瘤胃发酵参数、瘤胃微生物种群变化;采用DTAF荧光染料标记细菌（FLB）的一种新方法测定瘤胃原虫吞噬细菌速率和吞噬量的影响。【结果】山羊瘤胃液中pH值平均值的范围在6.85-7.16,在瘤胃的正常范围内;青蒿素能够降低NH3-N浓度,其中0.4%和0.6%两个处理组的瘤胃液中NH3-N浓度与对照组差异显著。青蒿素能够提高乙酸、丙酸及、总挥发性脂肪酸（TVFA）的摩尔浓度及丙酸的摩尔浓度百分比,能降低乙酸/丙酸比,各添加组的乙酸/丙酸比显著或极显著低于对照组(P＜0.05);随着青蒿素添加量的增加,细菌蛋白产量增加,其中,以0.6%添加组最高,与对照组差异极显著(P＜0.01);0.4%和0.6%添加组的原虫蛋白产量极显著低于对照组(P＜0.01);青蒿素对瘤胃液肽浓度的均值没有显著影响。同时,添加青蒿素后,瘤胃中细菌总数增加而原虫总数减少,使瘤胃原虫种属结构变化。添加青蒿素能显著影响原虫对细菌的吞噬速率,对照组和添加0.2%,0.4%和0.6%青蒿素处理组的吞噬速率分别为：320.11cells/（cell h）、313.94cells/（cell h）、305.00cells/（cell h）、278.14cells/（cell h）。【结论】添加青蒿素能显著影响瘤胃发酵类型,具有降低瘤胃中氨态氮浓度的趋势;同时可显著降低瘤胃中原虫密度,增加了细菌密度,改变瘤胃中原虫的种属构成比例;使瘤胃内毛虫比例显著降低,使双毛虫和等毛虫比例显著提高。添加0.6%青蒿素能显著降低山羊瘤胃内菌体蛋白的微循环,使山羊瘤胃原虫吞噬速率和微生物氮循环量减少而提高饲料蛋白质的潜在利用效率。  相似文献   

12.
选用6只体况良好、体重35 kg左右,年龄1.5岁左右的蒙古绵羊,研究体内驱除厌氧真菌对瘤胃微生物和发酵参数的影响.结果表明,驱除真菌导致绵羊瘤胃细菌总数和纤维分解细菌数量显著升高(P<0.05),毛口目原虫数量和原虫总数也明显增加(P<0.05),而内毛目原虫的数量没有变化.瘤胃内羧甲基纤维素酶的活力随厌氧真菌的消失而显著降低(P<0.05),但滤纸酶、木聚糖酶和果胶酶的活力并不受影响.驱除厌氧真菌后,瘤胃pH值和NH3-N浓度没有显著的变化(P>0.05);乙酸、丁酸和TVFA的浓度均出现下降,其中,乙酸浓度降低极为显著(P<0.01),其余两者表现为显著降低(P<0.05);丙酸浓度并没有受到驱除真菌的影响(P>0.05).对乙酸与丙酸摩尔比例的比较显示,驱除厌氧真菌显著降低了乙酸/丙酸的值(P<0.05),说明驱除厌氧真菌改变了瘤胃内的发酵模式,使之更趋向于乙酸减少的方向进行.  相似文献   

13.
The effects of treatment of chlorine dioxide (ClO2) gas on postharvest physiology and preservation quality of green bell peppers were studied. Green bell peppers were collected in bags and treated with 0, 5, 10, 20, and 50 mg L-1 ClO2 gas at 10 ± 0.5℃ for over 40 d, and the changes in postharvest physiology and preservation quality of the peppers were evaluated during the storage. The inhibition of rot of the peppers was observed for all the tested ClO2 gas treatments. The rot rates of the treated samples were 50% lesser than those of the control after day 40 of storage. The highest inhibitory effect was obtained after 50 mg L-1 ClO2 gas treatment, where the peppers did not decay until day 30 and showed only one-fourth of the rot rate of the control at day 40 of storage. The respiratory activity of the peppers was significantly (P ＜ 0.05) inhibited by 20 and 50 mg L-1 ClO2 treatments, whereas no significant effects on respiratory activity were observed with 5 and 10 mg L-1ClO2 treatments (P＞ 0.05). Except for 50 mg L-1 ClO2, malondialdenyde (MDA) contents in the peppers treated with 5,10, or 20 mg L-1 ClO2 were not significantly (P＞0.05) different from those in the control. Degradation of chlorophyll in the peppers was delayed by 5 mg L-1 ClO2, but promoted by 10, 20, or 50 mg L-1 ClO2. The vitamin C content, titratable acidity,and total soluble solids of the peppers treated by all the tested ClO2 gas did not significantly change during the storage.The results suggested that ClO2 gas treatment effectively delayed the postharvest physiological transformation of green peppers, inhibited decay and respiration, maintained some nutritional and sensory quality, and retarded MDA accumulation.  相似文献   

14.
In this study, the oxidative damage of α-terthienyl （α-T） to the Spodoptera litura （SL） cell and its mechanism were investigated. MTT was used to compare the toxicity of α-T and rotenone to the SL cell. The output of malondialdehyde and relative content of glutathione were determined with 2-thiobarbituric acid （TBA） and 5, 5＇-dithio-bis （2-nitrobenzoic acid） （DTNB）, respectively. Transmission electron microscope （TEM） was employed to observe the influence of α-T on the membrane and organelle of the SL cell. The result showed that the IC50 value of α-T to the SL cell was 0.21 μg mL^-1, whereas the corresponding dose of rotenone was 12.25 μg mL^-1. The output of MDA had the same changing tendency with the concentration of α-T, whereas the content of GSH had the negative correlation with it. According to TEM, the cell membrane and karyotheca swelled and couldn＇t retain integrity, the intracellular substances leaked out, unidentified granules appeared in the SL cell. The mitochondria expanded, and the membrane and subcellular organelle were damaged severely. In this study, it was found that after oxidative damage induced by α-T, the output of MDA increased notably, whereas the relative content of GSH decreased. This indicated that the antioxidant ability of cell weakened. The result of TEM implied that the SL cell suffered from oxidative damage under the appointed dose.  相似文献   

15.
This study was designed to control plant fertility by cell lethal gene Barnase expressing at specific developmental stage and in specific tissue of male organ under the control of Cre/lox system, for heterosis breeding of chili pepper （Capsicum annuum L.）. Chili pepper inbred lines （A, D, E, and I） were transformed with Cre gene and Barnase gene situated between loxp, separately, by means of Agrobacterium co-culture. In this study, we had established a high transformation system by extensive study of affecting factors including genotype, selection of marker, and lethal dose. Cotyledon with petiole from 9-11-day-old seeding was pre-cultured on media MR[MB（MS mineral＋vitamine B5）＋BA（6-Benzyladenine） 5.0 mg·L^-1 ＋IAA（indoleacetic acid） 1.0 mg·L^-1＋GA3（gibberellic acid） 1.0mg·L^-1＋sucrose 3%＋agar 6.5g·L^-1] for 2d. The explants were infected by Agrobacterium tumefaciens when their OD600（optical density at 600 nm）reached 0.6-0.9. After co-cultured for 4-5 d on media MC [MB＋BA5.0 mg·L^-1＋IAA 1.0 mg·L^-1 ＋GA3 1.0 mg·L^-1＋sucrose 3% ＋agar 6.5 g·L^-1＋AS （acetosyringone） 200μmol·L^-1, these cotyledons with petiole were cultured on selective differentiation medium in the media MT[MB medium supplemented with BA [5.0 mg·L^-1＋ IAA 1.0 mg·L^-1＋ GA3 1.0 mg·L^-1＋ AgNO3 5.0 mg·L^-1＋ CW （coconut water） 5% ＋ Km （kanamycin） 65 mg·L^-1＋ Cb （carbenicillin） 500 mg·L^-1＋ 3% sucrose ＋ agar 6.5 g·L^-1].The Kmr （kanamycin resistant） bud rosettes were elongated on selective elongation medium and rooted on rooting medium. PCR and Southern blotting analysis of Kmr plantlet indicated that the foreign genes had been integrated into the genome of pepper. The transgenic plants with Cre gene developed well, blossomed out, and set fruit normally. The transgenic plants with Barnase gene grew well with normal appearance of flower, but they showed different fertility from complete sterility, partial sterility to complete fertility, and similar results were obtained from in vitro pollen germination experiments.  相似文献   

16.
In order to assess the effects of chemical properties of soil salinity on electrical conductivity of 1：5 soil/water extract （EC1：5）, the study focused on revealing the main chemical factors contributing to EC of soil extracts and their relative importance. The relationship between EC1：5 and the chemical properties of soil salinity in the delta oasis of Weigan and Kuqa rivers, China, were studied using path coefficient analysis, a path analysis method. We studied each key element affecting EC1：5 either directly or indirectly. The results obtained show that the salt content, total dissolved solids （TDS）, and the sum of the sodium ion concentration and the kalium ion concentration are the most influential factors on 1：5 soil/ water extract （EC1：5） in the 0-10 cm and the 30-50 cm soil layer. The results show that the sequence of direct path coefficients in the 0-10 cm and the 30-50 cm soil layers on soil conductivity is TDS→Na^＋ ＋ K^＋→Salt content→Ca^2＋→Cl-→the sodium dianion ratio （SDR）→pH→ SO4^2-→HCO3^-→Mg^2＋→the soluble sodium percentage （SSP） sodium absorption ratio （SAR） and TDS→Salt content→Na^＋ ＋ K^＋→Ca^2＋→SDR→Mg^2＋→HCO3^-→SSP→pH→SO4^2-→SAR→Cl^-. The salt content, chlorine ion, and SAR are the main factors affecting 1：5 soil/water extract （EC1：5） in the 10-30 centimeter soil layer. The order of direct path coefficients result is as follows： Salt content→Cl^-→SAR→SSP→TDS→Ca^2＋→Mg^2＋= SO4^2-→HCO3^-→pH→SDR→Na^- ＋ K^＋. Moreover, the effects of HCO3^-, pH were very weak. Though the direct path coefficients between EC1：5 and SAR, SO4^2- and Ca^2＋ were not high, influence of other chemical factors caused the coefficients to increase, making the summation of their direct and indirect path coefficients relatively high. The models of the different soil layers were structured separately. Evidences showed that multiple regression relations between EC1：5 and most of the primary factors had sound reliability and very good accuracy. The research results can serve as a reference to the scientific management amelioration and utilization of saline in the Delta Oasis of Weigan and Kuqa rivers.  相似文献   

17.
The paper was to find the bacteria to degrade aflatoxin B 1 （AFB 1） and realize the application of biological degradation on AFB 1. Using cumarin as the carbon source and energy on the first screening, then the ten strains which were first screened out were taken to degrade AFB 1 100 pg kg^-1. Strain NMO-3 was screened out of ten strains, the degradation ratio of AFB 1 reached 85.7%, which was more prominent than the others （P 〈 0.01）. With the analysis of colony morphology, physiological and biochemistry experiments, and 16S rDNA gene sequence, the strain NMO-3 was finally identified as Stenotrophomonas sp. Using cumarin as the carbon source and energy could screen out the AFB 1 degradation strains. Acute toxicity tests show that the viable number of NMO-3 lower than 3.12 × 10^10 cfu mL-1 is safety. The crude enzyme was obtained by 65% ammonium sulfate fractionation, and it could degrade AFB1. It is the first report for the strain＇s detoxi- AFB1.  相似文献   

18.
In a completely randomized block design experiment, 16 ruminally cannulated male sheep with body weights of (40 ± 2.1) kg were fed twice daily (8:00 and 16:00) with concentrate and forage (50:50 on dry matter (DM) basis). Dietary treatments were supplemented with intraruminal doses of powdered Yucca schidigera extract (YSE) at the levels of 0 (control), 100, 200 and 300 mg · kg−1. On days of 15, 16 and 17 after feeding, ruminal content was sampled at 0, 2, 4, 6 and 8 h after dosing (8:00), and blood samples were collected at the end of experiment (the days 18 and 19 after feeding). Results showed that the treatment groups’ acidity was not affected (P = 0.13) by YSE. Comparing to the control, the ruminal propionate concentration was increased by YSE addition in a dose-dependent manner by up to 29.8% (P < 0.05), and the acetic concentration was decreased by up to 17.5% (P < 0.05). The ruminal ammonia concentration 2 hours after feeding was higher (P < 0.05) in sheep fed without YSE (increased by 17.57 mg· 100 mL−1) than those fed with YSE at 200 mg · kg−1 (6.77 mg · 100 mL−1 increase in NH3) and at 300 mg · kg−1 (6.50 mg· 100 mL−1 increase in NH3). Protozoal populations in the rumen were lower (P < 0.05) with the YSE feeding dose at 300 mg · kg−1 than the control. The serum chemistries were not different among treatments (P > 0.05) and were within the normal physiological ranges for sheep 19 days after feeding. The study indicated that 200 mg· kg−1 and 300 mg· kg−1 YSE groups had particular suppressing effects on ruminal ammonia concentration, ammonia-N concentrations and protozoal populations. The effect of YSE on ruminal fermentation could be attributed to the selective inhibitory effect on rumen microbial species. High level (300 mg · kg−1) YSE as feed additives resulted no negative impact on sheep in our tests.  相似文献   

19.
采用正交法建立了由栅藻(Scencdesmus obliquus)、小球藻(Chlorella vulgans)、亚硝化细菌(Nitritebacteria)、硝化细菌(Nitrate bacteria)组成的复合藻-菌净化系统去除氨态氮和亚硝酸态氮的最优化模型,确定了单胞藻与细菌的最优化数量配比关系,即栅藻∶小球藻∶亚硝酸化细菌∶硝化细菌=2.13∶1∶2.38∶3.73。利用该系统模型与单藻、单菌去除池塘老化水体中的氨态氮、亚硝酸态氮显示:去除氨态氮和亚硝酸态氮的效率远远高于单藻、单菌,其去除率分别为97.3%和68.8%。同时该系统模型还具有增加养殖水体溶解氧的作用,可使水体中的溶解氧在试验设定的参数中短时间达到9.7 mg.L-1,并可为水产动物提供1.6×106CFU.mL-1的天然藻类饵料。  相似文献   

20.
日粮精粗比对山羊瘤胃内微生物蛋白微循环的影响   总被引：3，自引：1，他引：2  
 【目的】以4只装有瘤胃瘘管的山羊为试验动物,研究不同精粗比日粮对山羊瘤胃微生态中原虫和细菌区系以及微生物蛋白微循环的影响规律。【方法】试验设精（玉米-豆饼）粗（稻草）比分别为10﹕90、30﹕70、50﹕50和70﹕30的4种日粮（A、B、C、D）,采用4×4拉丁方设计进行饲喂试验,采用荧光染色细菌技术测定瘤胃原虫对细菌的吞噬速率。【结果】日粮精粗比显著影响微生物细胞的密度。原虫密度C组最高;细菌和原虫的密度A组最低;日粮精粗比显著影响原虫吞噬的速率,A、B、C、D 4组的吞噬速率分别为：429.5、366.74、389.48、402.2 cells?cell-1?h-1,换算为对细菌N的吞噬速率分别为：2.319、1.98、2.103、2.172 pg N?cell-1?h-1。【结论】每天每头羊由于原虫的吞噬而造成的细菌N的循环损失估算分别为：136.49;369.02;485.99;440.56 mgN/（d?头）,即菌体蛋白损失为0.853、2.306、3.370和2.754 g/（d?头）,其中以C组菌体蛋白循环损失量最大,细菌周转率最高（3.07%）。  相似文献   

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