日光温室土壤盐分和养分的变化趋势

对种植 1～ 8a的日光温室土壤盐分和养分进行了调查研究 ,结果表明 ,随着日光温室种植年限的延长 ,土壤可溶性盐、电导率、养分含量呈增加趋势 ,酸碱度 (pH)呈降低趋势 ,有机质含量增幅不大 ;土壤速效养分中硝态氮含量过高 ,速效磷含量也很丰富。最后提出了温室土壤培肥和管理措施。     

不同覆土深度对鸡腿菇子实体产量的影响

本试验研究 11种覆土深度对鸡腿菇子实体产量影响。结果表明 ,不同覆土深度对子实体产量、有效子实体数和幼蕾数均存在显著的影响。覆土越厚 ,幼蕾数越少。当覆土深度在 0 5～ 3cm时 ,子实体产量和有效子实体数随着覆土层的加厚逐渐增加 ,在覆土深度为 3cm时达到最大值 ,覆土深度大于 3cm时 ,则随着覆土层的加厚而逐渐减少。从生产的角度看 ,覆土 3cm是比较适宜的覆土深度 ,此时的子实体产量最高。     

不同地域环境对枸杞蛋白质和药用氨基酸含量的影响

根据2000～2001年我国北方六省(区)多点枸杞采样资料和田间试验资料,利用K-均值聚类方法和非线性回归方法,对比分析了宁杞1号枸杞蛋白质和9种药用氨基酸含量的差异和特点,以及生态因子对它们的影响。分析结果表明,不同地域栽种的宁杞1号枸杞蛋白质和9种药用氨基酸含量的变异系数分别为16.58%和16.22%,除品种因子的决定作用以外,环境条件对枸杞蛋白质含量有一定作用,其中土壤水解氮含量对蛋白质和氨基酸合成有一定作用,二者呈对数关系。     

Changes of Ca2＋ activated potassium channels and cellular-proliferation in autogenous vein grafts

AIM: To investigate changes of Ca^2＋ activated potassium channels (K_Ca) in autogenous vein grafts. METHODS: The contraction of venous ring was measured by means of perfusion in vitro. The intimal proliferation and proliferation of cultured smooth muscle cells (vascular smooth muscle cells, VSMCs) were observed by the means of computerised image analysis and MTT method, respectively. Furthermore, whole cell mode of patch clamp was used to record K_Ca of VSMCs isolated from autogenous vein grafts. RESULTS: 1 week after transplantation there were no significant differences of contraction and intimal relative thickness between autogenous vein grafts and control. Contraction and intimal relative thickness of autogenous vein graft were significantly increased 2 weeks after transplantation (P＜0.05, n=8 vs control), and they were more enhanced 4 weeks after vein transplantation (P＜0.01, n=8 vs control). TEA (blocker of Ca^2＋ activated potassium channels) increased MTT A₄₉₀ value of VSMCs from femoral vein in a dose-dependent manner (P＜0.05, n=8). K_Ca current density was significantly attenuated in VSMCs from autogenous vein grafts 1-4 weeks after transplantation (P＜0.05, n=5). CONCLUSION: K_Ca was inhibited in autogenous vein graft, which accounted for vasospasm and intimal proliferation.     

137Cs示踪法在东北松嫩平原土壤侵蚀定量评价中的应用

根据不同退化程度草原和不同开垦年限农田土壤137Cs放射强度分析结果表明:与轻度退化草原相比,中度退化和重度退化中的137Cs放射强度分别下降了21%和52%。草原土壤开垦后,137Cs放射强度明显下降,开垦7年、15年、33年后,137Cs的放射强度分别只有轻度退化草原的37%、31%和26%。相关分析表明,伴随着土壤侵蚀的发生,土壤有机质含量、全N含量以及阳离子交换量下降。137Cs放射强度与土壤有机碳、土壤全N、交换性K和阳离子交换量呈极显著的正相关。     

Spatio-temporal factors influencing the occurrence of Syngamus trachea within release pens in the South West of England

Syngamus trachea is a pathogenic tracheal nematode that causes syngamiasis in wild and game birds, especially when birds are managed at high densities. Despite its pathogenic nature, very little is known about its epidemiology and relationship with ambient temperature and humidity. The spatial and temporal modelling of disease was undertaken on two pheasant estates within the South West of England from April 2014 to August 2014. Significant differences between the mean numbers of eggs per gram of soil were identified between pens at both site 1 and site 2 but did not differ significantly between sites. Egg abundance was significantly associated with soil moisture content, with greater egg survival between years in pens with higher average volumetric soil moisture content. Previous years stocking density and pen age were also associated with greater egg survival between years with more eggs being recovered in pens with greater stocking densities, and pens that had been sited longer. The greatest model to explain the variation in the numbers of eggs per gram of soil per pen was a combination of soil moisture content, stocking density and pen age.Larval recovery differed significantly between sites. Larval abundance was significantly and positively associated with temperature and relative humidity at site 1. Similarly, temperature and humidity were also positively and significantly associated with larval abundance at site 2. Rainfall did not influence larval recovery at either site 1 or site 2. The model with the greatest ability to explain larval abundance at both sites, was a combination of temperature, humidity and rainfall. Infection status (positive faecal egg counts) was significantly and positively associated with larval abundance at both sites, but rainfall was only positively associated at site 1. Temperature and humidity were positively associated with infection status at site 2, but not at site 1. The present study highlights the influence of climatic variables on both egg survival and larval abundance, and could therefore be used to develop more targeted treatment strategies around periods of higher disease risk. The frequent use of release pens is a clear factor in the epidemiology of syngamiasis, and it is recommended that pens be rested and/or rotated in order to reduce infection pressure in subsequent flocks.     

Management strategies for forage rape (Brassica napus L. cv Goliath): Impact on dry-matter yield,plant reserves,morphology and nutritive value

Limited information is available on the grazing management principles of forage rape (Brassica napus L.), particularly in relation to grazing height and intensity and the impact of these on dry-matter (DM) yield and nutritive value. A glasshouse study was undertaken to investigate the effect of three defoliation heights (plant height at harvest; DH: 40, 70 and 90 cm; L, M and H DH respectively) and three defoliation intensities (height at which plants were cut; DI: 5, 20 and 35 cm of residual height; H, M and L DI respectively) on forage rape (cv Goliath) yield and nutritive value at two harvests (harvest 1, H1 and harvest 2, H2), and the impact of nitrogen (N) and water soluble carbohydrate (WSC) reserves on regrowth. Increasing DH from L to H increased estimated total DM yield (H1 plus H2) from 0.5 to 4.6 t DM/ha but DI did not affect yield. Dry-matter yield was optimized at 90 cm DH, but greater nutritive value was achieved by harvesting at lower levels of DH. Despite high in vitro DM digestibility (IVDMD; 852–889 g/kg), harvesting at 90 cm DH could not meet the protein requirement of lactating dairy cows and harvesting at lower levels risks nitrate poisoning. Our results indicate the optimum DH may be between 70 and 90 cm DH, and 20 and 35 cm DI, which requires further studies.     

黄土高原人工灌草系统不同立地条件土壤种子库特征

本研究通过野外调查取样与室内试验相结合，连续两年对黄土高原人工灌草系统不同坡向、坡位进行取样，以期对该区土壤种子库的物种组成、密度特征及其物种多样性进行初步了解。研究结果表明：该人工灌草生态系统土壤种子库共有9科，15种，其组成因坡位、坡向以及年份而异；坡向、坡位均显著影响土壤种子库物种多样性指数、丰富度指数与土壤种子库密度（P<0.05），土壤种子库密度为3 218～5 492粒·m^-2，总体呈现为阴坡显著高于阳坡（P<0.05），下坡位显著高于上坡位（P<0.05）；坡位和坡向均对物种均匀性系数无显著影响；年份对土壤种子库无显著影响。上述研究可为黄土高原人工灌草系统的可持续利用与恢复提供参考依据。     

农五师葡萄钾素动态变化及调节措施研究

通过叶分析研究了不同葡萄品种叶柄全钾5～9月含量动态变化规律.结果表明:葡萄叶柄钾含量在生育期内整体呈波浪式下降趋势,前期下降迅速,中期平缓,进入浆果成熟期后又趋于下降；强势品种在整个生长季节内对钾的吸收大于弱势品种；早熟品种叶柄内钾含量变化趋势比晚熟品种提前.根据新疆农五师葡萄园区土壤有效钾含量分布现状,建议生产中应根据葡萄钾元素动态变化特点,不同团场应结合当地土壤有效钾含量相应补充.     

滴灌水肥一体化下施氮量对小麦氮素吸收及土壤硝态氮含量的影响

为探明华北地区山前平原水肥一体化条件下小麦合理的氮肥运筹。于2013-2015年2个小麦生长季,设置4个滴灌施氮量(N0-不施氮、N1-120 kg/hm~2、N2-240 kg/hm~2、N3-360 kg/hm~2)处理,研究滴灌水肥一体化下施氮量对小麦氮素吸收积累和土壤硝态氮含量的影响。结果表明:施氮量N1、N2和N3处理的小麦干质量及产量较处理N0显著增加,N1、N2和N3处理间无显著差异;施氮量对小麦茎秆的氮含量影响较大,但对籽粒氮含量的影响差异不显著;处理N3的小麦总吸氮量分别显著高于处理N0、N1和N2,但处理N1和N2之间无显著差异;氮肥收获指数以N2处理最高,氮肥当季回收利用率、氮肥农学效率、氮肥生产效率和氮肥利用效率均表现出随施氮量增加而降低的趋势;施氮量超过240 kg/hm~2,土壤硝态氮含量增加,且随种植年限的延长更加明显。采用一元二次方程拟合,获得小麦最高产量的施氮量为238.46~250.78 kg/hm~2,经济施氮量为174.28~207.18 kg/hm~2。综合考虑经济效益和生态效益,该条件下小麦滴灌经济施氮量以174~207 kg/hm~2为宜。