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本研究对西藏当雄不同退化程度高寒草甸土壤有机碳分布特征及其与土壤理化性质演变进行分析,结果表明,土壤有机碳及有机碳密度均为正常草甸土壤>轻度退化草甸土壤>严重退化草甸土壤,且0~10 cm土层中有机碳含量及其密度均高于10~20 cm土层土壤。回归分析表明,土壤有机碳与土壤活性有机碳、土壤碱解氮、速效磷、速效钾及土壤含水量之间存在显著或极显著的正相关关系,其决定系数R2分别为0.913 9、0.977 1、0.931 4、0.665 3和0.715 6,直线回归方程分别为y=0.074 3x-0.026 1,y=2.676 8x+14.425 0,y=0.245 9x+3.347 9,y=4.296 5x+71.667 0,y=0.790 8x+5.424 5;而与土壤容重呈显著负相关关系（y=-0.016 7x+1.553 1）。土壤有机碳的损失,造成土壤养分和水分减少,土壤容重增大。通径分析表明,土壤有机碳的变化对碱解氮的影响最显著。 相似文献
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六种牧草种子大小和播种深度对出苗的影响 总被引：17，自引：3，他引：17
西方冰草、沙生冰草、草地早熟禾、绿针茅、粗羊茅及匍茎翦股颖 6种牧草的种子在塑料杯中分 0 .5 cm、0 .75 cm、1.5 cm、3.0 cm和 6 .0 cm的不同深度 ,分别播种在土壤、人工土壤和沙土上。当 p=0 .0 1时 ,土壤 (S) ,种子大小 (SE) ,播种深度 (D) ,S× SE,SE× D和 S× SE×D的相互作用对出苗率的影响均有显著差异。随着播种深度的增加每一种牧草的出苗率都有所降低。西方冰草在所有播种深度下出苗最好 ,而匍茎翦股颖在沙土中出苗最好。西方冰草与沙生冰草在 3.0 cm和 6 .0 cm的播种深度下出苗较好。种子大小还与胚芽鞘长度 (R=0 .96 ,P=0 .0 5 ,3.0 cm播种深度 ) ,苗高 (R=0 .99,P=0 .0 1,3.0 cm播种深度 )和根长 (R=0 .96 ,P=0 .0 1,3.0 cm播种深度 )之间的相关关系显著。土壤对出苗具有显著的影响 (LSD0 .0 5=0 .10 13)。 相似文献
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对91份不同产地扁穗冰草(Agropyron cristatum(L.)Gaertn)样品的遗传多样性和遗传结构进行研究。采用叶绿体cpDNAtrnT-trnL直接测序的方法和邻接法(NJ)对91份扁穗冰草样品进行遗传多样性和遗传结构分析。结果显示:物种水平上单倍型多样性(Hd)指数为0.608,核苷酸多样性(Pi)指数为0.00295;种群水平上Hd介于0~0.9722,Pi指数介于0~0.00749。分子方差分析表明,扁穗冰草大部分遗传变异(91.63%)发生在居群内,居群间的基因流(Nm=5.474)较高,群体内变异是扁穗冰草的主要变异来源;NJ树表明,受试的6个野生种群可分为4大类群。扁穗冰草的遗传多样性居群内遗传分化较大。 相似文献
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“雪狐”扁穗冰草是禾本科冰草属长寿型多年生草本植物。须根十分发达，茎秆直立、丛生，株高50-70cm叶长5～10cm，宽0．2～0．5cm；穗状花序长5～7cm，小穗水平排列呈蓖齿状，种子黄褐色，千粒重约2．0g。 相似文献
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以扁穗冰草和沙芦草为研究对象,采用5℃、10℃、15℃、20℃和25℃的低温胁迫处理,测定发芽率、发芽势、胚根长、胚芽长、电导率和丙二醛（MDA）含量,探讨2种牧草种子萌发期抗寒性。结果表明：扁穗冰草在5℃低温胁迫不能发芽、沙芦草能够发芽,10℃和15℃低温胁迫处理下沙芦草的发芽率、发芽势、胚芽长和胚根长都高于扁穗冰草,电导率和丙二醛含量低于扁穗冰草,20℃低温胁迫处理下沙芦草发芽率、发芽势、胚芽长和胚根长与扁穗冰草比,不形成显著差异,电导率和丙二醛含量也与扁穗冰草不形成显著差异;25℃低温胁迫处理下扁穗冰草的发芽率、发芽势、胚芽长和胚根长高于沙芦草。综合表明,沙芦草种子萌发期抗寒性强于扁穗冰草种子。 相似文献
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农牧交错带退耕还草对土壤酶活性的影响 总被引：14，自引：8，他引：6
在中国农业大学国家草地生态系统沾源野外观测站,以马铃薯地为对照,研究了北方农牧交错带退耕地建植多年生人工草地对土壤酶活性的影响.研究结果表明,退耕地种草后土壤有机质含量提高,土壤微生物繁殖速度加快,提高了土壤的脲酶、酸、碱件磷酸酶和脱氢酶活性,且0～10 cm土层酶活性变化较10～20 cm土层显著.土壤酶活性与土壤碳、氮含量之间呈显著、极显著的正相关关系.土壤酶活性受生长季节影响较大,但无明显的规律性变化.5种人工草地(扁穗冰草、草地雀麦、无芒雀麦、羊草和紫花苜蓿草地)土壤酶活性存在差异,但因季节因素的影响,很难确定哪种人工草地对土壤酶活性的影响最大. 相似文献
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基于我国农药信息网数据和新修订的《食品安全国家标准 食品中农药最大残留限量》（GB 2763 — 2021）中葡萄相关指标,结合葡萄生产实际,对我国葡萄上农药登记的现状及生产中农药的应用情况进行梳理,指出了存在的问题,分析了产生问题的原因,提出了相应建议,以期为我国葡萄的安全生产提供参考。 相似文献
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MV Root Kustritz 《Reproduction in domestic animals = Zuchthygiene》2012,47(Z4):214-222
Surgical sterilization of dogs and cats is a well-accepted measure for population control in some countries, but is considered unethical as an elective surgery in other countries. This is a review of what is known regarding positive and negative effects of gonadectomy surgery on individual animals and on societal management of unowned dog and cat populations. 相似文献
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K Fegeros G Papadopoulos G Zervas E Ziras B Cafantaris 《Archives of Animal Nutrition》1989,39(11):921-931
Two experiments were conducted to evaluate the effects of sugar beet molasses (0, 8 and 16%) with or without lasalocid sodium (33 ppm) on rumen liquor and blood parameters of sheep, and on fattening reared Karagouniko breed lambs. In Expt. 1 six adult Karagouniko fistulated wethers were fed six different pelleted diets. The results showed that lasalocid decreased (P less than 0.01) total VFAs concentration in the rumen (7.1%) by reducing (P less than 0.001) acetic, n-butyric and iso-valeric acids while increased (P less than 0.001) propionic acid concentrations. The same trends were observed in molar proportions of the individual VFAs. The total VFAs production was also depressed by 13.75% when molasses were used at the level of 16%. No interaction among the main treatments was observed with the exception of L X M with 16% molasses where the propionic acid concentration decreased, and those of butyric and iso-valeric acids increased. Lasalocid did not alter the mean values of rumen liquor pH and ammonia nitrogen concentration while molasses increased the later parameter. No significant differences on dietary protein degradability were observed among treatments. Lasalocid reduced the beta-HBA concentration by 13% in the blood while molasses increased it (P less than 0.001). Free fatty acids' concentration was decreased by the molasses inclusion to the diets, while lasalocid didn't alter blood glucose concentration. Finally, the number of protozoa in the rumen liquor was reduced by 49 and 70% at 0 and 5 hours post feeding respectively with the addition of lasalocid to the diets, regardless of the use of molasses. In Expt. 2 utilized 86 weaned male Karagouniko fattening lambs, with initial mean LW 13 kg, for 60 days. They were assigned to six groups and fed ad libitum with diets of the same composition as in Exp 1. Lasalocid increased the growth rate by 8.6%, reduced feed consumption by 4.8% (P less than 0.005) and improved feed conversion by 11.8%. Molasses also improved growth rate by 16-34% and increased feed consumption by 15-22%. The interaction of L X M to feed consumption was significant (P less than 0.001). None of the treatments had an effect on carcass characteristics. Finally lasalocid showed its positive action when it was used in combination with molasses in ruminants' diets. 相似文献
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Dr G. Milisits E. Kovács O. Pőcze J. Ujvári Zs. Taraszenkó G. Jekkel 《British poultry science》2010,51(2):289-295
1.?Using the so-called TOBEC (Total Body Electrical Conductivity) method, which allows the determination of egg composition in vivo, correlations between egg composition, hatchability and hatched chicks’ development were studied.
2.?A total of 1500 hen eggs (Ross-308) were measured by TOBEC, and eggs with extremely high (10%, n = 150), extremely low (10%, n = 150) and average (10%, n = 150) electrical conductivity values were chosen for further investigation.
3.?During the incubation period, it was observed that eggs with high electrical conductivity had a significantly higher mortality than eggs with low electrical conductivity.
4.?It was observed that both the increase in electrical conductivity at the same egg weight, and the increase in egg weight at the same electrical conductivity resulted in an increase in the hatching weight.
5.?It was found that the dry matter, protein and fat content of the chicks hatched from eggs with low electrical conductivity was higher at hatching than that of the chicks hatched from eggs with high electrical conductivity.
6.?At 42 d of age the liveweight of cocks and pullets hatched from eggs with low electrical conductivity was 3·2 and 8·2% higher than the liveweight of cocks and pullets hatched from eggs with high electrical conductivity.
7.?Because of the higher liveweight at slaughter, there was a significant superiority of the chicks hatched from eggs with low electrical conductivity in the case of the examined carcase traits at slaughter.
8.?Similar tendencies were found also in the ratios of carcase variables to liveweight, but the between group differences were not statistically significant in this case.
9.?Based on the results it was concluded that TOBEC seems to be a useful method for separating eggs with different composition.
10.?This could be a good starting point for further in vivo investigations in order to clarify the effect of egg composition on hatchability and further development. 相似文献
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A total of 260 New Zealand White growing rabbits were used to study the effect of diet on chemical composition of cecal contents and on production and composition of soft and hard feces. Eight diets varying in their acid detergent fiber (9.8% to 32.7%) and starch (13% to 30%) levels were evaluated. The diet affected (P less than .01) all the variables studied, except dry matter (DM) and molar proportions of volatile fatty acids on cecal contents. An increase of dietary crude fiber increased crude fiber level in cecal contents (from 11.58% to 26.53%). However, a relatively lower proportion of fibrous material was found in the cecal contents when rabbits were fed the more fibrous diets. This suggests that dietary fiber has a direct influence on the efficiency of particle separation in the digestive tract. Crude protein and volatile fatty acid concentrations of cecal contents decreased (from 30.14% to 19.65% and from 47.8 to 36.7 mmol/liter, respectively) when dietary crude fiber increased. This could be related to availability of energy to cecal microorganisms. Ammonia concentration of cecal contents was not affected by dietary crude fiber. Daily production of soft feces varied from 14.98 to 29.59 g DM/d, and the contribution of soft feces to total DM and to crude protein intake ranged from 10.6% to 15.0% and from 12.8% to 20.5%, respectively; these values were the smallest and the largest for the least and the most fibrous diets, respectively. From this study we conclude that dietary fiber has a major effect on the digestive processes in the rabbit and that dietary starch level has no influence on any of the variables studied. 相似文献
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血根碱药理及毒理作用的研究进展 总被引：1，自引：0，他引：1
血根碱(sanguinarine)作为一种苯菲啶异喹啉类生物碱,具有抗菌、抗炎、抗氧化、抗肿瘤、改善肝功能及诱导细胞凋亡等作用,同时对肝脏、心脏等具有一定的毒性。作者就血根碱对细菌、真菌和癌细胞的药理作用及毒性作一综述,为该药在临床中的有效合理应用奠定基础。 相似文献
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