有机培肥与耕作方式对稻麦轮作土壤团聚体和有机碳组分的影响

为了明确不同外源有机物和耕作方式对土壤地力培育的影响,以水稻-小麦轮作系统为对象,通过2个年度(2016—2018年)大田试验研究了外源有机物(秸秆和有机肥)和耕作方式及其交互作用[稻麦秸秆还田配合旋耕(SR),稻麦秸秆还田配合翻耕(SP),秸秆不还田、增施有机肥配合旋耕(MR),秸秆不还田、增施有机肥配合翻耕(MP),秸秆不还田、不施用有机肥、旋耕深度15 cm(CKR)]对土壤团聚体和有机碳组成的短期影响。结果表明:SR处理能够降低水稻季土壤容重并增加总孔隙度。相比CKR,小麦季SR处理显著增加0.05mm水稳性团聚体含量,增加量为7.2%。此外,外源有机物和耕作对土壤有机碳活性组分具有显著影响。其中,易氧化有机碳(EOC)主要受耕作与有机物交互作用影响,酸水解有机碳(LPIc和LPII_c)主要受耕作措施的影响, SR处理的土壤EOC和LPI_c含量比CKR提高0.3～2.6 g·kg~(-1)。颗粒有机碳(POC)主要受外源有机物的影响,并且秸秆还田处理POC平均含量高于增施有机肥处理,增加量为0.75g·kg~(-1)。短期内,外源有机物和耕作及其交互作用对稳定性有机碳(黑碳和矿物结合态有机碳)的影响较小。综上,秸秆还田配合旋耕有助于提高土壤水稳性团聚体和活性有机碳的含量(EOC、LPI_c和POC)。     

冬枣溃疡病病原初步鉴定

2003~2004年在山东省滨州市沾化县、无棣县等冬枣产区调查发现,冬枣生长前期在枣吊和叶片上发生了一种细菌性新病害。通过对典型病害样本进行病原菌分离、纯化获得20个菌株。从中选出4个菌株进行致病性测定,同时对其细菌形态、培养性状、染色反应、生理生化测定及血清学反应等性状进行了较为系统研究。结果表明,该地区冬枣溃疡病是由油菜黄单胞Xanthom onas campestrisPamm e(Dowson,1939)侵染引起的。     

胚胎冷冻技术及其在转基因小鼠中的应用

随着生物工程技术的发展,出现了许多生物工程小鼠品系,促使胚胎冷冻技术得到了广泛应用。胚胎冷冻技术不仅为转基因动物提供可用胚胎,还使胚胎移植不受时间、地域限制,简化引种过程,防止疾病传播,为建立优良动物的胚胎库提供了条件。综述了几种常用的胚胎冷冻方法及其在转基因小鼠中的应用研究,指出了胚胎冷冻方法存在的主要问题,并展望了其发展前景。     

造林密度对新疆杨人工林生长发育和光合特性的影响

【目的】探索河西绿洲区新疆杨适宜种植密度,为新疆杨人工林的集约栽培提供科学依据.【方法】以新疆杨(Populus alba L.var.pyramidalis Bge.)为研究对象,研究3种造林密度(株距×行距分别为2m×3m、3m×4m、4m×5m)对新疆杨生长发育及光合特性的影响.【结果】不同造林密度间新疆杨人工林单株材积、胸径、树高均存在显著差异,并随林龄增加差异更加明显.4m×5m配置新疆杨人工林的胸径、单株材积大于其他两种密度,同时具有较高的光合速率(P_n)、蒸腾速率(T_r)、气孔导度(Gs)和较低的胞间CO_2浓度(C_i).相关分析表明,日均Pn、Tr与胸径、树高、单株材积呈显著正相关,Gs仅与树高呈显著正相关,C_i与各生长指标均呈负相关.【结论】株距×行距为4m×5m配置是河西新疆杨种植的最佳密度.     

冬春温度变化对小麦温敏雄性不育系BNS的育性转换影响

BNS是一个主体受温度控制的新型小麦雄性不育系,表现为花粉发育在低温下(8℃)不育,高温下(12℃)可育。BNS不育性稳定,但年份间常有波动,一些年份自交结实率上升显著。为了弄清楚BNS育性波动的原因,连续3a观察不同播期的BNS穗分化过程,分析连续6a调查的BNS自交结实率与对应年份的冬春温度变化,结果发现,冬季和春季温度的改变显著影响BNS的自交结实率。一般规律是,暖冬年份自交结实率低,寒冬较高,暖春年份自交结实率高,寒春较低。该现象的形成主要是BNS冬季生长发育速度所致,暖冬年份BNS冬季仍保持生长,到春季时完成温度敏感期前的发育,较早进入温度敏感期,此时的春季温度较低,因此BNS不育;然而在寒冬年份,BNS停止生长,春季需生长一定时间才进入温度敏感期,进入时气温已较高,因此诱导育性转换,自交结实率增高。BNS冬季生长发育速度在穗分化观察中得到验证。该机理解释了不同年份BNS自交结实率的波动,并根据冬春温度可预测BNS的育性转换。     

15℃以上平均气温显著影响温敏雄性不育小麦BNS的育性转换

BNS是一个对温度敏感的小麦雄性不育系,敏感期低温表现不育,高温恢复可育。2014/2015年度小麦生育期间温度相对较高,但BNS的自交结实率比温度相对较低的2011/2012年度低50%以上。为探讨该现象产生的原因,对近4a（2012-2015年）小麦生育期的温度走向,以及温度与BNS自交结实率的关系进行分析。温度走向结果分析表明,不同冬、春温度变化显著影响BNS结实率,暖冬和寒春易降低结实率,寒冬和暖春可提高结实率。这些结果对BNS的影响可能是,暖冬穗发育加快,进入感温期早,再遇正常年份或暖春,育性转换完成快,结实率高,反之结实率低。2014/2015年度属典型暖冬和寒春气候特点,故BNS结实率严重下降。相关分析结果表明,BNS的自交结实率与播种-抽穗的各积温因子均呈负相关,而与翌年3月1日-抽穗的平均温度≥15℃有效积温和平均温度≥15℃的累积日数呈显著正相关;BNS育性转换的温度阈值为12℃,15℃以上温度对自交结实率影响显著;用两个正相关显著的温度参数建立的回归方程可预测BNS自交结实率。研究结果表明,15℃以上平均气温显著影响温敏雄性不育小麦BNS的育性转换,平均温度≥15℃有效积温和平均温度≥15℃的累积日数是两个重要的BNS育性转换温度因子参数。     

内蒙古杭锦旗北部盐碱田温湿盐动态与生产利用

为探析水-热-盐关系以及植被对盐碱田改良的意义,利用2008年8月2日-8月6日在内蒙古杭锦旗黄河灌区盐碱田进行的试验观测数据,主要通过方差分析与典型相关分析方法对3个样地(裸地、紫花苜蓿地和玉米地)土壤温度(0-30cm土层)、湿度(0-20cm土层)、盐度(0-100cm土层)的动态变化进行了分析。结果表明,3个样地的温(度)-湿(度)-盐(度)动态基本呈现裸地苜蓿地玉米地的格局;0-5cm地温与耕作层(0-20cm)的土壤水分具有显著相关关系,是0-30cm土层内地温驱动水盐动态的主要热力因子;植物能够减少土壤表层积盐,并可以降低碱化度;苜蓿地比玉米地具有更低的钠吸附比值。在盐碱地区选择耐盐碱牧草品种开展草田轮作,有益于盐碱土壤的改良与利用。     

高产高效栽培下春玉米生育后期冠层结构及其光合特性的研究

以郑单958为供试品种,设高产高效栽培(GCGX)和农户传统栽培(CK)2个处理,于2012年和2013年连续2 a进行田间试验,测定春玉米生育后期冠层结构及其光合特性的变化规律。结果表明：吐丝期和乳熟期株高、穗位高产高效栽培略高于农户传统栽培。与农户传统栽培相比,高产高效栽培春玉米叶面积指数较大,在生育期上表现为吐丝之后更为明显,在叶位上表现为棒三叶以下叶片最为突出;不同叶位的叶倾角高产高效栽培显著小于农户传统栽培,而叶向值均显著大于农户传统栽培,在棒三叶表现最为明显;高产高效栽培生育后期净光合速率显著高于农户传统栽培,冠层光合能力极显著高于农户传统栽培。高产高效栽培下春玉米产量为14.009 t·hm^-2(2012)和13.255 t·hm^-2(2013),均极显著高于农户传统栽培。     

Heterogeneity of Hypertrophy in Feline Hypertrophic Heart Disease

Eighty-six cats with non-dilated left ventricular myocardial hypertrophy were studied retrospectively. Cats were categorized by two-dimensional echocardiography as having symmetric ventricular hypertrophy (Type I), asymmetric with predominant septal thickening hypertrophy (Type II), and asymmetric hypertrophy with predominant free-wall thickening (Type III). The distribution of hypertrophy was judged subjectively and objectively. Subjective and objective results were similar (P= 0.03) although overlap existed between groups. Morphologic patterns (Types I, II, and III) were compared with breed, age, sex, heart rate, percent fractional shortening, left atrial size, serum creatinine concentration, and the presence (yes/no) of pleural effusion, pulmonary edema, pericardial effusion, heart murmur, dyspnea, thromboembolism, hyperthyroidism, and being alive at the time of study. Interventricular septal thickness, left ventricular free wall thickness, percent fractional shortening, and left atrial size additionally were compared to 3-month survival. Cats with Type HI hypertrophy were more likely to experience thromboembolism than cats with Type II hypertrophy (P= 0.05) and cats with Type I hypertrophy were more likely to have heart murmurs than cats with Type III (P= 0.02). No other significant associations were found in comparison to pattern of hypertrophy. Both left atrial size and percent fractional shortening significantly correlated with 3-month survival (P < 0.001 for each). The degree of interventricular septal wall thickness was associated with 3-month survival (P= 0.02) when known hyperthyroid cats were excluded from the study group, while left ventricular free wall thickness consistently was not associated with survival. This study demonstrates the heterogeneity of hypertrophy in cats with hyper-trophic heart disease and provides predictors of survival (left atrial size, percent fractional shortening, and interventricular septal wall thickness when compared with euthanasia/spontaneous death data).     

Omentum-Enhanced Reconstruction of Chronic Nonhealing Wounds in Cats: Techniques and Clinical Use

The greater omentum was used to aid in the reconstruction of nonhealing wounds in five cats. In each cat the cause of the nonhealing wound could not be determined. A vascular omental pedicle was created at laparotomy by dividing the dorsal leaf of the omentum at its pancreatic attachments (four cats) or by dividing the ventral leaf at its gastric attachments (one cat). The pedicle was then passed through either the ventral or lateral body wall into the nonhealing wound via a subcutaneous tunnel. The wounds were closed over the omentum after local tissue mobilization. All the wounds healed uneventfully and have remained healed with a mean follow-up period of 2.5 years. Complications included intestinal herniation through a ventral midline exit hole (one cat), presumed abdominal fat herniation through a ventral abdominal exit hole (one cat) and seroma formation (one cat). All of the complications were treated successfully. The omentum should be considered a useful adjunct in the treatment of nonhealing wounds in cats.