科尔沁沙地土地利用时空演变及空间自相关分析——以奈曼旗为例

利用奈曼旗2000、2006、2012年和2018年4期遥感数据，在ENVI5.3和ArcGIS10.2的支持下，运用土地利用动态变化空间分析模型、空间变化率指数和土地利用程度空间自相关，分析奈曼旗土地利用时空动态演变规律，为科尔沁沙地沙漠化土地治理及生态环境恢复提供参考信息。结果表明:1）各沙漠化土地整体呈逆转趋势，耕地、林草地和建筑用地呈发展趋势，研究区生态环境逐渐好转；2）人口增长、经济发展和政府政策导致耕地和林草地空间变化呈扩展型，各沙漠化土地呈衰退型；3）耕地和林草地与同期其他土地利用类型转化幅度逐年增长，空间变化率指数逐年增加，各沙化土地空间变化率指数逐年下降，仍需坚持生态环境恢复，沙漠化土地重点治理；4）土地利用程度呈高度空间自相关，在空间上的聚集区域固定，高-高值聚集在南部黄土区，面积逐年减少，低-低值聚集在中部沙区，面积减少幅度较小。     

IGF2基因表达调控及其遗传变异在动物生长发育中的研究进展

胰岛素样生长因子2（insulin-like growth factor 2，IGF2）作为胰岛素类激素家族中重要成员之一，广泛参与机体众多生理代谢过程，在癌症发生、神经调节、糖代谢疾病、骨质疏松、肌肉发育和脂肪沉积等方面具有重要的作用，其功能行使主要通过与受体IGF1R和IGF2R结合或与胰岛素样生长因子结合蛋白IGFBPs和IGF2BPs竞争性结合发挥功能。鉴于IGF2基因在肌肉发育和脂肪沉积中的重要作用，发掘IGF2基因相关分子标记并解析其内在调控机理，在畜牧生产中具有重要的意义。研究发现，众多IGF2基因遗传变异与动物的生长发育之间存在显著相关关系，其可能通过影响IGF2基因印记、甲基化状态、转录因子结合或miRNA靶向结合型转录后调控等方式发挥作用。因此，文章综述了IGF2基因表达调控模式，包括IGF2与其受体的调控关系，基因印记与miRNA参与的表观遗传调控，转录因子对其的调节作用，遗传变异等方面的内容，以期为IGF2基因在动物生长发育调控相关研究中提供相应的借鉴，为分子育种提供有效线索。     

痕量灌溉对棉花花铃期光合性能日变化及产量的影响

【目的】明确痕量灌溉方式在干旱区灌溉棉田的适用性。【方法】本研究以中棉所92为供试材料,系统监测了痕量灌溉不同埋管深度30 cm(D30)、40 cm(D40)和50 cm(D50)和膜下滴灌(CK)4个处理的棉花花铃期光合日变化及产量效应。【结果】①不同处理下净光合速率和气孔导度的日变化均呈双峰曲线变化趋势,且D30处理各时段的净光合速率和气孔导度均高于其他处理。②不同处理下的胞间CO2摩尔分数日变化均呈广口"V"字形双峰曲线变化趋势,蒸腾速率日变化均呈单峰曲线变化趋势,最大值出现在14:00h。③D30处理的2年平均籽棉产量和平均皮棉产量最高,分别为5 734.28和2 454.53 kg/hm^2,其中籽棉产量分别比CK、D40和D50处理高出1.09%、7.63%和11.38%,皮棉产量分别比CK、D40和D50处理高出3.49%、8.32%和1.61%。【结论】综合光合性能日变化和产量分析得出,内蒙古阿拉善地区采用埋管深度为30 cm的痕量灌溉技术为最佳。     

Variation and heritability of morphological and physiological traits among Leymus chinensis genotypes under different environmental conditions

Intraspecific trait variation and heritability in different environmental conditions not only suggest a potential for an evolutionary response but also have important ecological consequences at the population, community, and ecosystem levels. However, the contribution of quantitative trait variation within a grassland species to evolutionary responses or ecological consequences is seldom documented. Leymus chinensis is an important dominant species in semi-arid grasslands of China, which has seriously suffered from drought and high temperature stresses in recent decades. In the present study, we measured variation and heritability of 10 quantitative traits, namely the number of tillers, maximum shoot height, number of rhizomes, maximum rhizome length, rhizome mass, aboveground mass, root mass, maximum net photosynthetic rate(Pmax), specific leaf area(SLA), and leaf length to leaf width ratio(LL/LW), for 10 genotypes of L. chinensis under one non-stress(Ck) condition and three environmental stress conditions(i.e., drought(Dr), high temperature(Ht), and both drought and high temperature(DrHt)). Result indicated that(1) the interaction of genotype and environmental condition(G×E) was significant for 6 traits but not significant for the other 4 traits as shown by two-way analysis of variance(ANOVA), suggesting that different selection forces were placed for different traits on the factors dominating phenotypic responses to different environmental conditions. Moreover, these significant G×E effects on traits indicated significantly different phenotypic adaptive responses among L. chinensis genotypes to different environmental conditions. Additionally, individuals could be grouped according to environmental condition rather than genotype as shown by canonical discriminant analysis, indicating that environmental condition played a more important role in affecting phenotypic variation than genotype;(2) by one-way ANOVA, significant differences among L. chinensis genotypes were found in all 10 traits under Ck and Dr conditions, in 8 traits under Dr Ht condition and only in 4 traits under Ht condition; and(3) all 10 traits showed relatively low or non-measurable broad-sense heritability(H_2) under stress conditions. However, the lowest H_2 value for most traits did not occur under DrHt condition, which supported the hypothesis of 'unfavorable conditions have unpredictable effects' rather than 'unfavorable conditions decrease heritability'. Results from our experiment might aid to improve predictions on the potential impacts of climate changes on L. chinensis and eventually species conservation and ecosystem restoration.     

植保机在线混药系统的设计及混药性能试验

为提高植保机喷雾作业中的农药利用率,设计了一种在线混药系统。混药系统主要包括取水单元、取药单元、混合器和控制单元。系统工作时,控制单元控制取水单元和取药单元抽取水溶液和农药,注入混合器混合,混合液经隔膜泵加压后经过喷头喷施。基于计算流体力学理论,建立内置7块扰流板且注药口和注水口沿边壁垂直分布并正对第1块扰流板的圆柱形静态混合器模型,运用Fluent软件对模型进行数值分析,结果常压(0.1MPa)时,混合器出口处药水混合均匀性变异系数为2.2%,药水混合效果最佳,但注药口有药剂回流现象,故提出药剂加压的模拟方案。药剂加压1MPa时,注药口无药剂回流现象,药水混合均匀性变异系数为2.0%,药水混合效果优于常压。用胭脂红溶液替代农药进行试验,加压状态下,混药系统喷头处混药稳定性最大相对误差为4.301%,药水混合变异系数最大,为3.989%,混药性能优于常压,与仿真结果基本吻合;对在线混药系统进行隔膜泵变工况试验,结果水流量在35～140 L/min时,药水配比为(1∶300)～(1∶3 000)时,在线混药系统混合均匀性系数最大,为4.670%。     

1985—2015年中国县域芝麻生产的时空演变

为阐明我国芝麻生产的时空变化特征，基于1985—2015年的我国县域芝麻生产统计数据，采用集中度、重心迁移、产量贡献率、优势度等指标，对我国芝麻种植面积、产量和单产的时空动态变化进行分析。结果表明:1)1985—2015年，我国芝麻产量和面积的分布基本一致，主要集中在大别山山脉一带和辽宁省西北部；全国芝麻单产水平不断提升，种植面积自2000年起小幅缩减，而产量变化处于明显的波动状态。2)30年间，全国芝麻产量集中度和面积集中度变化波动较小，集中地区分布发生了一定的变化；我国芝麻产量、面积重心同步向南偏西方向迁移，迁移距离分别为252和344 km。3)我国芝麻生产的主导因素一直为面积，占比为40.0%—49.9%；我国芝麻的生产优势区主要在河南、安徽、湖北、江西四省。近30年来，我国芝麻种植变化受其自身特性、病虫害、湿害以及政策等影响，芝麻生产受到一定的限制。因此，优化和调整我国芝麻生产的政策倾向、种植结构、良种研发以及栽培管理等方面尤显关键。     

田园综合体建设初期土地利用效益综合评价——以鲁家村为例

以鲁家村田园综合体项目为例,构建田园综合体土地利用效益评价指标体系,综合运用层次分析法和变异系数法组合确定指标权重,并从社会效益、经济效益、生态效益3方面对其土地利用效益进行综合分析,以期为田园综合体建设提供借鉴。结果显示:鲁家村田园综合体建设初期土地利用效益评价中,社会效益、经济效益、生态效益所占比重依次减小。鲁家村土地利用效益在田园综合体规划实施后有较大提升,社会效益、经济效益于2016—2017年增幅较大,2017—2018年增幅较小;生态效益在2016—2018年总体呈现稳定小幅增长。总的来看,鲁家村田园综合体建设对当地社会发展、经济提升、生态保护等均有正向影响,且在短期内社会效益、经济效益显著,而生态效应提升不明显。     

基质栽培黄瓜叶片水分状况、光合与荧光参数对不同灌水下限的响应

为探明基质栽培黄瓜适宜的灌水下限,实现农艺节水,以黄瓜品种博特209为试材,采用基质盆栽,共设置4个灌水下限处理,即田间持水量的50%、60%、70%、80%,用A、B、C、D表示,灌水上限统一设定为田间持水量的90%,采用TDR350水分速测仪控制基质的水分含量,研究不同灌水下限对基质栽培黄瓜叶片水分状况、光合日变化及荧光参数的影响。结果表明:随着灌水下限的提高,叶片的相对含水量、自由水含量及自由水/束缚水的比值呈逐渐上升的趋势,水分饱和亏、叶片细胞汁液浓度及束缚水含量则呈下降趋势,处理C、D的相对含水量、自由水含量均显著(P<0.05)高于处理A、B,处理A细胞汁液浓度显著高于处理C、D,处理A、B束缚水含量显著(P<0.05)高于处理C、D。叶绿素a、叶绿素b和叶绿素a+b的含量均随灌水下限的升高呈现为先上升后下降的趋势,而类胡萝卜素含量则表现为先下降后上升的趋势,处理C叶绿素a、叶绿素a+b含量显著(P<0.05)高于处理A、B;处理C、D黄瓜叶片的胞间二氧化碳浓度(C_i)的变化趋势基本呈“V”型,而处理A、B的Ci的变化趋势基本呈“W”型;处理A、B、C、D的蒸腾速率(T_r)日变化均呈先上升后下降的趋势,处理B、C、D的Tr在14:00后呈现逐渐下降的趋势,而处理A在12:00后就呈快速下降的趋势;处理B、C、D的气孔导度(G_s)日变化大致呈“M”型的双峰曲线,处理A则呈单峰曲线;处理A、B、C、D叶片净光合速率(P_n)与G_s日变化趋势基本一致,在整个日变化过程中,处理C、D的P_n始终高于处理A、B。F_v/F_m、Φ_PSⅡ、qP随灌水下限的提高呈逐渐上升的趋势,而NPQ呈逐渐下降的趋势。研究结果表明,灌水下限为田间持水量的70%~80%,基质栽培黄瓜叶片的水分状况良好、光合色素含量高、净光合速率大,有利于黄瓜的光合作用,促进黄瓜的生长发育。     

Reducing crude protein variability and maximizing savings when formulating corn-soybean meal-based feeds

Crude protein in corn and soybean meal have been documented to vary, and such inherent variability can result in under- or over-feeding of CP when feeds are formulated, leading to reduced bird growth, added input costs, and increased environmental pollution. The purpose of this study was to compare 2 grain-handling techniques and 2 feed formulation methods (linear vs. stochastic programming) to reduce CP variability in finished feeds and determine resulting costs or savings. The 2 grain-handling techniques were placing all the random batches of each delivered ingredient in to (1) a single bin (1-bin method) or (2) segregating above- and below-average samples into 2 bins (2-bin method). A fast way of estimating the composition of the ingredients is now available (near-infrared reflectance spectroscopy). Microsoft Excel workbooks were constructed to solve broiler starter feed formulation problems. Formulating feeds by linear and stochastic models based on the 2-bin method reduced CP variability by at least 50% compared with the 1-bin method. Formula cost was reduced by ˜20 cents per ton (averages of August 2012 United States ingredient prices) when the 2-bin method was used with the linear model. Formulating feed with a margin of safety increased formula cost by $3.40 per ton. Stochastic feed formulation increased formula cost to meet the specified CP level in feed at any probability of success, and formula cost was reduced substantially with the 2-bin method (up to $6.47 per ton). The magnitude of savings and reduced feed variability suggested that, regardless of the costs associated with building extra bins, the 2-bin method can be economically efficient in the long run. Therefore, it could be possible to split the batches of feed ingredients at a feed mill into above- or below-average bins before feed formulation to reduce CP variability and to maximize savings.