播期和密度对滴灌冬小麦群体结构与抗倒特性的影响

以新冬22(少穗型)和邯郸5316(多穗型)为供试材料,采用裂区田间试验设计,主区为3个播期:9月23日(B1)、10月4日(B2)和10月15日(B3);副区为4个播种密度:315万株·hm^-2(M1)、510万株·hm^-2(M2)、705万株·hm^-2(M3)、900万株·hm^-2(M4),研究不同播期和密度对滴灌冬小麦群体动态和抗倒特性的影响。结果表明:(1)滴灌冬小麦生育期随播期推迟而缩短,B3处理的新冬22和邯郸5316的生育期较B2处理缩短11 d,较B1处理缩短22 d;密度对生育进程影响较小。(2)群体大小和叶面积指数(LAI)随密度增加而增加,随播期推迟而减小;晚播群体在生育后期总茎数有追赶正常播期处理的趋势;同一密度下B2处理和同一播期下M2或M3处理的群体大小和叶面积动态随生育进程变化最小,表现出较好的叶片调节功能。(3)随播种密度增加,滴灌冬小麦基部节间和重心高度增加,基部直径、机械强度和抗倒指数下降;随播期延迟,茎秆基部节间变短,重心高度下降,直径增大,机械强度和抗倒指数增加;密度对茎秆性状的影响大于播期;在实际生产中,充分发挥密度和播期的互作效应,适当增加晚播处理的密度,能优化个体生长,保证高产。(4)B2处理的平均产量较B1、B3处理分别提高8.09%~17.52%和16.01%~21.07%,新冬22和邯郸5316分别在B2M3和B2M2处理中产量最高,分别达8 541.04 kg·hm^-2和9 218.08 kg·hm^-2。(5)从群个体生长的角度上看,新冬22对密度反应更敏感,邯郸5316对播期反应更敏感;说明生产中少穗型品种应注重合理密度前提下调节播期,而多穗型品种应注重适当播期前提下调节密度,以充分发挥品种的增产潜力。     

冬春低温雨雪天气设施蔬菜防灾减灾技术Disaster prevention and reduction technology of vegetables grown in facilities in winter and spring cold weather 凌丽云 凌彬青 程艳

近年来,屯溪区冬春季低温寒潮、大雪、霜冻等极端灾害性气候频繁发生,对农业生产特别是设施蔬菜造成损失尤为严重,要密切关注天气情况,及早采取科学预防措施和灾后处理等管理措施,可以最大限度减少因灾给设施蔬菜生产带来的经济损失。     

Selection on gamete recognition proteins depends on sex, density, and genotype frequency

Gamete recognition proteins can evolve at astonishing rates and lie at the heart of reproductive isolation and speciation in diverse taxa. However, the source of selection driving this evolution remains unknown. We report on how the sperm bindin genotype influences reproductive success under natural conditions. An interaction between genotype frequency and spawning density determines how sperm bindin genotype influences reproductive success. Common genotypes are selected under sperm-limited conditions, whereas rare genotypes are selected under conditions of intense sperm competition and sexual conflict. Variation in the evolutionary rates of bindin may reflect historic differences in sperm availability.     

西北肉用绵羊新品种群陶滩寒蒙组合生长发育性状的比较研究

以引进的无角陶赛特羊与滩羊、小尾寒羊和蒙古羊不同杂交组合的后代(F1、F2及F3)为研究对象,采用随机抽样的方法对已培育出的西北肉用绵羊新品种群部分杂交组合生长发育性状以及在不同月龄的体重、体高和体长等指标进行测定与分析,探讨培育新品种的最佳杂交组合模式.结果表明:杂种三代生长发育速度快于对应杂种二代,杂种二代生长发育速度快于对应杂种一代;3种杂交组合改良小尾寒羊和蒙古羊效果都好,尤其是高代或三元杂交经济效应更为显著.选择理想型的三代或二代杂种羊进行横交固定培育新品种的技术方案是可行的,培育的新品种群是国内肉用绵羊育种计划最具代表性和遗传性能表现最好的育种基础群和最宝贵的种质资源.     

冬小麦产量与群体整齐度遗传分析

文章以12个冬小麦品系为试验材料,收获后分析其产量性状、农艺性状和群体整齐度。探究有显著差异性状遗传力及群体整齐度对产量及产量构成影响。结果表明,穗长整齐度和穗粒数整齐度与小麦产量及千粒重显著相关。育种过程中,通过提高冬小麦穗长和穗粒数整齐度增加冬小麦产量是有效途径。     

基因型、年龄和性别对羊肉胆固醇含量的影响

实验选用兰得瑞斯羊及其杂种为实验动物,采用冷式提取脂肪的方法以及气相色谱(GC)技术测定了肉羊背最长肌肌肉中胆固醇含量。实验研究了不同基因型、不同年龄以及不同性别肉羊肌肉中的胆固醇的变化以及这些因素对肉中胆固醇含量的影响。研究结果表明,年龄对脂肪中胆固醇含量有明显地影响作用。羊肉脂肪中的胆固醇含量随个体年龄的增长而下降。肌肉中胆固醇的含量以50日龄时为最高,达到748mg/kg,150日龄时胆固醇含量374mg/kg为最低,100日龄时胆固醇含量居中为502mg/kg。3个实验组的差异极显著 (P<0.01)。虽然单从实验的数字上看,纯种肉羊和75 % 杂种羊脂肪中胆固醇的含量比50 % 杂种羊的要高,但性别和基因型对羊体脂中胆固醇的含量影响都不显著(P>0.05)。还表明,羊肉脂肪中的胆固醇含量随着年龄的增长而下降,幼年肉羊肌肉中的胆固醇相对含量要显著的高于成年羊。因为,成年羊的体脂中饱和性脂肪酸的含量高于羔羊。因此,无论从市场角度还是从健康角度看,羊肉的生产以1岁左右的羊为最佳。     

Improving methods of studying weather and winter hardiness of plants under changed climate conditions

It is shown that the existing method of evaluating winter weather based on a change in the sums of negative temperatures doesn??t take into account the frequent occurrence of an unfavorable factor for plants??increasing evaporativity. In connection with desiccation of plant tissues, this leads to a decrease in the yield of fruit, berry, and winter cereal crops and also indicates imperfection of the winter-hardiness index and, accordingly, breeding process and agricultural practices of growing them. To eliminate the shortcomings of the method, it is suggested to characterize the weather by evaporativity and to supplement winter hardiness with the water-holding capacity index of one-year shoots and leaves of herbaceous plants.     

湖南省冬汛期两次暴雨天气过程对比分析

利用NCEP/NCAR分辨率1°×1°的再分析资料,从环流形势、水汽、动力以及不稳定层结4个方面,对比分析2015年11月发生在湖南省两次秋冬季暴雨天气过程。结果表明,两次暴雨过程与异常的大尺度环流背景有关。副高面积偏大强度偏强有利于水汽沿着副高西南侧汇入湖南省,极涡的强度较常年平均异常偏强,使得冷空气强度偏强,南下的强冷空气与北上的暖湿气流交汇,引发强降水天气过程。地面倒槽和中低层低涡切变是两次强降水过程的主要影响系统,过程2地面倒槽强度较强、范围较广且移动缓慢,对应中低层低涡切变强度较大,过程1地面倒槽和中低层低涡切变无论是强度、范围还是持续时间都不及过程2。700 h Pa的水汽是两次区域性暴雨的主要输送源,过程1水汽主要来源于南海,过程2来源于孟加拉湾,且水汽条件强于过程1。过程1垂直上升运动区向上延伸的高度更高,低层辐合层深厚,锋区较强,有不稳定能量积累。过程2主要以稳定性降水为主,垂直上升运动、辐合辐散配置较浅薄,主要集中在中低层。     

水稻叶片形态、群体结构和产量对种植密度的响应

为了分析水稻叶片形态、群体结构和产量对种植密度的响应,以中籼稻高产选系JW10、JW103、JW113和JW34为材料,研究了不同种植密度[低密度(1 hm21.8×105穴)、中等密度(1 hm23.0×105穴)、高密度(1 hm24.2×105穴)]条件下水稻叶片形态、叶面积指数、叶面积垂直分布、光合速率、叶绿素荧光参数、干物质生产和产量形成的特点。结果表明,不同密度处理下,水稻叶片宽度及披垂度均发生了变化。中等密度处理下,齐穗期水稻上层叶面积比例高于低密度和高密度处理;中等密度处理下齐穗期水稻的光合速率和叶绿素荧光参数(Fv/Fm)居于低密度处理与高密度处理之间,但随齐穗后天数的增加,中等密度处理下水稻光合能力的优势逐渐增大。因此,在现有的生产条件和技术水平下,维持1 hm23.0×105穴的种植密度是水稻取得高产的基础。     

南通近四年冬小麦种植的气象条件分析

笔者利用2003—2007年南通气象局的气象资料和南通市农业局的冬小麦试验资料,分析了南通市近四年冬小麦各生育阶段的气象条件,采用综合对比的方法,分析了南通市气象变化特点对冬小麦产量及其构成因素的影响,结果表明南通地区这四年的气象条件较有利于小麦生长。     

种植密度对晚播冬小麦氮素同化积累分配及利用效率的影响

研究了种植密度对晚播小麦氮素同化积累分配及氮素利用效率的影响。以重穗型冬小麦品种兰考矮早八为材料,在晚播期(10-24—10-26)设低(150万株/hm2)、中(225万株/hm2)、高(300万株/hm2)3个种植密度进行了2年大田试验。传统播期(10-10—10-12)为对照。结果表明,晚播小麦旗叶的硝酸还原酶活性和可溶性蛋白含量显著提高,单茎氮素积累量、营养器官转移氮素对籽粒氮素积累的贡献率以及植株的氮素收获指数和氮素吸收效率均提高,而氮素利用效率和籽粒产量降低。对照播期的低、中密度处理的氮代谢酶活性、氮素积累量和氮素利用效率及籽粒产量较高,而晚播处理则以中、高密度处理较高。不同播期的中密度处理的蛋白质含量和籽粒产量高于其他2个密度处理。因此,晚播条件下兰考矮早八兼顾高产和高效利用氮素的适宜播种密度为225~300万株/hm2。     

冬小麦遭遇低温寒潮早春田间管理措施

2009年11月以来,北方冬麦区连续遭遇低温寒潮天气,冬小麦遭受不同程度的冻害,引起各级政府的关注。农业部提出各地要积极采取应对措施降低灾情影响。为确保冬小麦丰产丰收,提出天津地区冬小麦遭遇低温寒潮早春田间管理措施,希望广大农户参照执行。     

密度与氮素水平对小黑麦群体动态、产量及构成因素的影响

以小黑麦东农5305为材料,设置氮水平和栽培密度两个因子,施氮量0、75、150、225kg·hm-2;密度300、450、600万株·hm-2,研究了不同密度与氮素水平对小黑麦分蘖成穗及产量构成的影响。结果表明,东农5305在300万株·hm-2、75kg·hm-2处理时茎蘖成穗率最高,产量也最高。由此可知,对于分蘖能力较高的东农5305应适当降低基本苗,少施氮肥,主攻穗粒数和千粒重,实现高产。     

郑州城区鸟类冬季集群调查分析

1999-2003年，作者连续4a对郑州城区冬季鸟类集群进行调查，共记录5目、11科、26种鸟类．其中冬候乌1种，夏候鸟1种，留鸟21种，旅鸟3种；古北界鸟类11种，东洋界鸟类5种，广布性鸟类10种．夏候鸟夜鹭跨季节分布，冬季集群数量近2000只，白头鸽、八哥、乌鸫跨区域分布，四季于郑州活动；智力最高的鸦科混群近10000只；最大集群、优势种灰椋鸟与树麻雀，冬季集群数量均具有20000只以上．显示了该城区鸟类冬季集群的季节性与地理分布多样性特征。     

Relation between population density and body size in stream communities

The existence of a general relation between population density and body size in animal assemblages has been debated because of known biases and ambiguities in the published data and data handling. Using new comprehensive data sets from two geographically separated stream communities that encompass 448 and 260 invertebrate taxa with a wide range of body sizes, we show that an inverse proportionality between density and body size is a consistent feature in these communities. The scaling across taxa is not statistically different between the two systems, indicating a convergent pattern of communities. Variation in the regression slope among different taxonomic groups indicates that these communities are not governed universally by a single ecological or energetic rule.     

Nutrient deficiency limits population development,yield formation,and nutrient uptake of direct sown winter oilseed rape

Direct-sowing establishment method has great significance in improving winter oilseed rape(Brassica napus L.) production and guaranteeing edible oil security in China. However, nutrient responses on direct sown winter oilseed rape(DOR) performance and population development dynamic are still not well understood. Therefore, five on-farm experiments were conducted in the reaches of the Yangtze River(RYR) to determine the effects of nitrogen(N), phosphorus(P), and potassium(K) deficiencies on population density, dry matter production, nutrient uptake, seed yield, and yield components of DOR plants. Four fertilization treatments included the balanced NPK application treatment(NPK, 180 kg N, 39.3 kg P, 100 kg K, and 1.8 kg borax ha–1) and three nutrient deficiency treatments based on the NPK treatment, i.e., –N, –P, and –K. The results indicated that DOR population density declined gradually throughout the growing season, especially at over-wintering and pod-development stages. Nutrient deficiency decreased nutrient concentration in DOR plants, limited dry matter production and nutrient uptake, and thereby exacerbated density reduction during plants growth. The poor individual growth and reduced population density together decreased seed yield in the nutrient deficiency treatment. Averaged across all the experiments, seed yield reduced 61% by N deficiency, 38.3% by P deficiency, and 14.4% by K deficiency. The negative effects of nutrient deficiency on DOR performances followed the order of –N>–P>–K, and the effects were various among different nutrient deficiencies. Although N deficiency improved DOR emergence, but it seriously limited dry matter production and nutrient uptake, which in turn led to substantial plants death and therefore resulted in a very low harvested density. The P deficiency significantly reduced initial density, limited plants growth, and exacerbated density reduction. The K deficiency mainly decreased individual growth and yield, but did not affect density dynamic. Our results highlighted the importance of balanced NPK application in DOR production, suggesting that management strategy of these nutrients should be comprehensively considered with an aim to build an appropriate population structure with balanced plant density and individual growth.     

Nutrient deficiency limits population development,yield formation,and nutrient uptake of direct sown winter oilseed rape

Direct-sowing establishment method has great significance in improving winter oilseed rape (Brassica napus L.) production and guaranteeing edible oil security in China. However, nutrient responses on direct sown winter oilseed rape (DOR) performance and population development dynamic are still not well understood. Therefore, five on-farm experiments were conducted in the reaches of the Yangtze River (RYR) to determine the effects of nitrogen (N), phosphorus (P), and potassium (K) deficiencies on population density, dry matter production, nutrient uptake, seed yield, and yield components of DOR plants. Four fertilization treatments included the balanced NPK application treatment (NPK, 180 kg N, 39.3 kg P, 100 kg K, and 1.8 kg borax ha–1) and three nutrient deficiency treatments based on the NPK treatment, i.e., –N, –P, and –K. The results indicated that DOR population density declined gradually throughout the growing season, especially at over-wintering and pod-development stages. Nutrient deficiency decreased nutrient concentration in DOR plants, limited dry matter production and nutrient uptake, and thereby exacerbated density reduction during plants growth. The poor individual growth and reduced population density together decreased seed yield in the nutrient deficiency treatment. Averaged across all the experiments, seed yield reduced 61% by N deficiency, 38.3% by P deficiency, and 14.4% by K deficiency. The negative effects of nutrient deficiency on DOR performances followed the order of –N>–P>–K, and the effects were various among different nutrient deficiencies. Although N deficiency improved DOR emergence, but it seriously limited dry matter production and nutrient uptake, which in turn led to substantial plants death and therefore resulted in a very low harvested density. The P deficiency significantly reduced initial density, limited plants growth, and exacerbated density reduction. The K deficiency mainly decreased individual growth and yield, but did not affect density dynamic. Our results highlighted the importance of balanced NPK application in DOR production, suggesting that management strategy of these nutrients should be comprehensively considered with an aim to build an appropriate population structure with balanced plant density and individual growth.