油茶水浸液对紫苏种子萌发及幼苗生长的化感效应

以武汉野生紫苏种子为材料,研究了不同浓度油茶水浸液对紫苏种子萌发和幼苗生长的影响.结果表明:低浓度(0.005、0.010、0.020 g/mL)的油茶水浸液对紫苏种子的萌发无显著影响;中等浓度(0.030 g/mL)可显著促进种子萌发;高浓度(0.040 g/mL)则显著抑制紫苏种子萌发.油茶水浸液对紫苏幼苗根生长表现为明显的低促高抑作用,对茎生长则表现出一定的促进作用,其中浓度为0.030 g/mL促进作用最为明显.     

Identification and fine mapping of a candidate gene for oil yellow leaf 2 conferring yellow leaf phenotype in maize

Leaf colour is an important agronomic trait for studying molecular mechanisms in chlorophyll biosynthesis and chloroplast development. Here, a novel mutant oil yellow leaf 2 (Oy2) with a typical yellow leaf phenotype at the seedling stage was identified from the mutant population derived from the maize inbred line RP125. Compared with wild type, Oy2 mutant displays decreased chlorophyll content, reduced photosynthetic capacity and impaired chloroplast structure, which is likely controlled by a single recessive gene. The Oy2 locus was then delimited into a 117 kb region on chromosome 5 harbouring four genes, amongst which the gene Zm00001d013013, encoding a magnesium chelatase subunit D, was identified as the only candidate gene associated with Oy2 mutant phenotype. Moreover, the expression levels of candidate gene Oy2 and genes associated with chlorophyll biosynthesis and photosynthesis were tested by RNA‐seq and qRT‐PCR, implying that the causal gene Oy2 playing a critical role in chlorophyll synthesis. Taken together, we propose that the causal gene Oy2 highly associated with the yellow leaf phenotype may be helpful in elucidating photosynthetic pigments biosynthesis and chloroplast development in maize.     

水稻抗倒伏特性及其与茎秆性状的相关性研究

以22个中籼稻品种(组合)为对象,研究了水稻倒伏的敏感期和敏感节位,及倒伏指数与茎秆性状的相关性.结果表明:水稻的倒伏敏感期是在齐穗后21～28 d,敏感节位是基部第一个伸长节间;相关分析和通径分析表明倒伏指数与节间长、基部节间到穗顶的长和基部节间至穗顶的鲜重呈极显著正相关,与基部节间外径、基部抗折力、基部节间壁厚、单位节间干重和秆形指数呈极显著负相关.抗折力对倒伏指数的负向直接作用最大,其次是单位节间干重.说明改善水稻茎秆的质地结构、增加基部节间的充实度是提高水稻的抗倒伏能力的关键.     

受限空间下散热对微火焰稳定性的影响

以无水液体乙醇为燃料,用铁铬合金电热丝为燃烧室内反应物加热,采用实验与数值模拟相结合的方法研究乙醇-空气小尺度层流扩散火焰散热对受限空间微火焰稳定性的影响。结果表明,采用电热丝向受限空间内的燃烧反应物加热,可以减少散热损失的影响,对稳燃有一定的帮助。电加热功率为合适值时,稳定燃烧极限最宽。电加热可提高火焰温度,增大化学反应速率,使火焰中心向上游移动。一定范围内,电加热功率的增幅大于散热的增幅,外加热功率对散热损失有抑制作用,增强微火焰的稳定性。     

具有α-葡萄糖苷酶抑制活性的益生乳酸菌筛选

利用α-葡萄糖苷酶抑制剂体外筛选模型,分析了来源于传统乳制品的10株乳杆菌对猪小肠提取的α-葡萄糖苷酶的抑制活性;对这些菌株的基本益生特性,包括对人工模拟胃肠液的耐受性及对肠上皮细胞的粘附性等进行了评价;最后,通过Caco-2细胞建立的Transwell模型分析了乳杆菌对人肠道α-葡萄糖苷酶活性及其基因表达的影响。结果表明,这10株乳杆菌对猪小肠提取的α-葡萄糖苷酶均具有不同程度的抑制作用;乳杆菌的α-葡萄糖苷酶抑制活性在菌株生长的对数期或稳定期达到高峰,随后出现下降的趋势;结合菌株的基本益生特性评价发现,有3株具有较高抑制活性的乳杆菌能够耐受人工模拟的胃肠液,并具有较强的黏附肠上皮细胞HT-29的能力;由Transwell模型发现,乳杆菌能同时抑制α-葡萄糖苷酶的活性及基因表达量。研究表明,筛选出的3株乳杆菌（副干酪乳杆菌L14和Z3-11以及植物乳杆菌NL42）均具有较高的α-葡萄糖苷酶抑制活性和较好的益生特性,可作为潜在的辅助降血糖的益生菌株。     

燃油荷电改善雾化的机理与试验研究

燃油荷电改善雾化是在发动机上节能降排的一种新尝试。本文从理论上分析了燃油荷电改善经的基本原理,设计了适当的荷电装置,并在荷电装置的基础上分析了尖端电极电压、燃油流速、桶状电极内径对荷质比的影响。最后在发动机气道试验台上用ＹＳＣ－１型运动粒子瞬态激光全息测试仪,拍摄了汽油带电荷雾化和不带电荷雾化时的粒子全息图,结果证明荷电后燃油雾化粒子的粒径变小,且尺寸统一。     

微白黄链霉菌对谷子萌发及拔节期生长的作用及机制

为探究外源放线菌对谷子种子萌发、拔节期植株生长的影响,本研究以一株微白黄链霉菌（Streptomyces albidoflavus）T4为供试菌株,以无菌水为对照,通过培养皿试验分析T4发酵液原液、10、100、1 000倍稀释液对谷子种子萌发的影响;以无菌剂添加处理作为对照,通过盆栽试验探究T4活菌制剂包衣和拌土对拔节期谷子植株生长及根际微生物的作用。结果表明,T4发酵液处理提高了谷子种子的萌发率,尤其以培养前期的提高幅度较大。T4发酵液的原液、10和100倍稀释液处理使谷子培养24 h后的萌发率与无菌水对照相比分别增加了5.8、6.7和9.2个百分点,100倍稀释液使谷子的发芽势、发芽指数和胚根长较对照分别提高了9.2个百分点、23.1%和13.4%。盆栽试验中,与无菌剂对照相比,包衣施加T4菌剂处理拔节期谷子地上植株生物量和根系生物量分别提高了22.5%和32.7%;根尖数和根分叉数分别增加了90.9%和66.9%;根际细菌（B）数量和微生物总数分别增加了95.1%和49.5%;真菌（F）数量减少了52.1%;放线菌（A）与真菌的数量比值（A/F）、细菌与真菌的数量比值（B/F）...     

不同缓控释氮肥对连作春玉米产量及氮肥去向的影响

在山西省连作春玉米区连续4年设置大田定位试验,设置不施氮肥(CK)、一次性基施尿素(CU1)、追施尿素(CU2)、树脂包膜尿素(PCU)、硫包衣尿素(SCU)、多酶金缓释尿素(MEU)6个施肥处理,研究施用缓控释氮肥对春玉米产量、氮肥去向及氮素平衡的影响,为春玉米氮素养分的科学管理技术提供参考。结果表明:(1)缓控释氮肥处理能够明显提高春玉米产量,促进氮素吸收。与CU1处理相比,SCU、MEU、PCU和CU2处理可分别提高春玉米产量17.51%,9.88%,9.62%,9.48%,同时氮肥农学利用效率分别提高7.5,4.2,4.1,4.1 kg/kg。(2)不同缓控释氮肥处理的作物吸收肥料氮以及肥料氮在0-100 cm土层残留量之间存在显著差异。SCU、MEU、PCU、CU2和CU1的氮肥表观利用率分别为36.1%,32.5%,26.5%,26.7%,19.5%,肥料氮在0-100 cm土层残留量分别占施氮量的28.5%,31.6%,35.7%,35.5%,39.1%。此外,与一次性基施尿素相比,缓控释氮肥能够显著降低肥料氮的损失,SCU、MEU、PCU和CU2分别降低了22.65%,18.81%,8.99%,8.47%。(3)综合分析不同氮肥处理的农田氮素平衡,SCU处理的春玉米吸氮量最高,为261.5 kg/hm^2,其次是MEU,为253.5 kg/hm^2。SCU的0-100 cm土层残留量在缓控释氮肥中最低,为124.1 kg/hm^2,MEU和PCU分别为131.04,140.09 kg/hm^2。SCU处理的氮表观损失量最低,为106.3 kg/hm^2,MEU和PCU分别为111.6,125.1 kg/hm^2。在山西省春玉米主产区土壤上,缓控释氮肥能够显著促进春玉米对氮素的吸收,减少氮素损失。硫包衣尿素和多酶金缓释尿素的效果相对较好。     

Satellite-based estimation of evapotranspiration of an old-growth temperate mixed forest

Evapotranspiration (ET) is a key flux in the water cycle and has strong seasonal dynamics for forest ecosystems. Recently eddy flux covariance measurements are continuously taken at a temperate mixed forest in Northeastern China since 2002. In an effort to better understanding the factors that control the seasonal dynamics of ET, here we (1) calculate ecosystem-level water use efficiency (WUE) from observed water and CO₂ flux data, and (2) relate the resultant WUE with satellite-derived vegetation indices, and (3) develop and evaluate a simple model that uses satellite images and climate data as input data to predict ET on the coupling of photosynthesis and transpiration processes. Ground WUE estimates obtained from eddy covariance tower were correlated with moderate resolution imaging spectroradiometer (MODIS) vegetation indexes (VIs) and ground micrometeorological data over 3 years (2003–2005). The enhanced vegetation index (EVI) was more closely correlated (r = 0.82) with WUE than the normalized difference vegetation index (NDVI; r = 0.64). Air temperature (T_A) measured over the canopy was the meteorological variable that was most closely correlated with WUE (r = 0.74) over years. For the significant correlation between EVI and T_A (r = 0.82, P < 0.05), EVI was selected as the single variable to predict WUE to simplify calculation. We calculated ET by ET = GPP/WUE, gross primary production (GPP) was predicted by vegetation photosynthesis model (VPM) that uses satellite images and meteorological variables. At a temporal resolution of 8 days, the annual curves showed good correspondence between measured and predicted values of WUE and ET in terms of phase and magnitude for each year. Seasonally integrated predicted ET was +4% (in 2003), +2% (in 2004), +0.4% (in 2005) higher than observed values.