中国稻谷生产率的地域差异和时空分异——基于稻谷主产区的实证分析

农业结构调整的背景下，提高稻谷的生产效率对于保障我国口粮安全具有重要意义。采用1999-2015年全国籼稻和粳稻主产省的数据，利用数据包络分析法对我国各省份各年度稻谷生产效率的DEA-Malmquist指数进行了测算，通过测算得出反映稻谷全要素生产率的Malmqusit指数，并将全要素生产率分解为规模效率变化、纯技术效率变化和技术进步变化。结果表明：①稻谷主产区区域布局方面，水稻产业可以结合地区优势布局。②技术进步在稻谷的投入产出效率的提高中发挥了重要作用。在推广水稻种植中，农业部门应充分重视技术进步的作用。③发展适度规模经营，提高规模效率，提高稻谷生产效率。未来稻谷产业仍以去库存、绿色发展、规模化经营为主要趋势。     

不同磷水平柱花草磷效率及根构型研究

为研究不同磷水平下柱花草磷效率的基因型差异及其与根构型的关系，利用盆栽试验，以磷低效、磷高效、磷敏感3种基因型柱花草品种为材料，研究0、0020、0035、0050、0075、0100、0200 g·kg-1共7个磷水平下，不同基因型柱花草的磷营养特性；并进一步比较两个代表性基因型（磷低效、磷高效）柱花草在对照(0 g·kg-1)、缺磷(0010 g·kg-1)、正常磷（0025 g·kg-1）处理下苗期根系生长状况，从而确定根构型与磷效率的关系。结果表明：不同基因型植株的磷含量、吸磷量随磷浓度的增加而增加，磷利用效率对磷浓度的反应趋势则相反。在不同磷处理下，磷高效基因型的磷利用效率均较高，且随着磷浓度的增加不同基因型品种磷利用效率的变化趋势度表现为：磷高效＜磷低效＜磷敏感。随着磷胁迫的加重，磷高效和磷低效基因型的侧根数、主根长、根体积、根表面积和根活跃吸收面积均增加，根直径减小。磷高效基因型柱花草根体积显著高于磷低效基因型，且在其他根构型指标上优于磷低效基因型。磷高效基因型品种较耐低磷，柱花草根系形态的改变是其适应低磷胁迫的重要机制。研究为柱花草的优质栽培提供理论依据。     

Analysis of the variations in dry matter yield and resource use efficiency of maize under different rates of nitrogen,phosphorous and water supply

Abstract

Increasing resources use efficiency in intensive cultivation systems of maize (Zea mays L.) can play an important role in increasing the production and sustainability of agricultural systems. The objectives of the present study were to evaluate DM yield and the efficiency of inputs uses under different levels of water, nitrogen (N) and phosphorus (P) in maize. Therefore, three levels of irrigation including 80 (ETc₈₀), 100 (ETc₁₀₀) and 120% (ETc₁₂₀) of crop evapotranspiration were considered as the main plots, and the factorial combination of three levels of zero (N₀), 200 (N₂₀₀) and 400 (N₄₀₀) kg N ha^?1 with three levels of zero (P₀), 100(P₁₀₀) and 200 (P₂₀₀) kg P ha^?1 was considered as the sub plots. The results showed that increasing the consumption of water and P was led to the reduction of N and P utilization efficiency, while RUE increased. WUE was also increased in response to application of N and P, but decreased when ET_C increased. DM yield under ETc₈₀ treatment reduced by 11 and 12%, respectively, compared to ETc₁₀₀ and ETc₁₂₀ which was due to reduction of cumulative absorbed radiation (R_abs(cum)) and RUE. Under these conditions, changes of stomatal conductance (gs) had little effect on DM yield. It was also found that N limitation caused 11 and 20% reduction in DM yield compared to N₂₀₀ and N₄₀₀, respectively. This yield reduction was mainly the result of decrease in RUE. By decreasing R_abs(cum), P deficiency also reduced DM yield by 5 and 9%, respectively, relative to P₁₀₀ and P₂₀₀ treatments.     

不同光质组合对生菜生长和能量利用效率的影响

【目的】筛选较优的光质组合,提高人工光植物工厂生菜产量和能量利用效率。【方法】以光强为200μmol/(m~2·s),R/B为4/1的红蓝光(RB)为对照,在光强为150μmol/(m~2·s),R/B为4/1的红蓝背景光基础上,分别添加50μmol/(m~2·s)的绿光(G)、黄光(Y)、橙光(O)和远红光(FR)组成4种不同光质组合处理,分别用RBG、RBY、RBO和RBFR表示,对不同光质组合处理生菜的生长及形态、光合能力、能量利用效率等指标进行比较研究。【结果】RBG、RBO和RBFR处理生菜地上部鲜质量较RB处理分别增加14.5%,14.5%和30.8%,地上部干质量分别增加13.3%,24.1%和29.9%(P0.05)。RBG处理可以增加生菜的株高、总叶面积、净光合速率和能量利用效率。与RB处理相比,RBY处理对生菜的地上部干、鲜质量影响不显著;RBO处理可以提高生菜叶片的光合能力和能量利用效率。RBFR处理可以增加生菜的地上部干、鲜质量,但在实际生产中,生菜叶片较易出现烧尖现象。【结论】RBG和RBO是工光植物工厂生产中较为合适的光质组合。     

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。     

Time‐lapse monitoring of soil water content using electromagnetic conductivity imaging

The volumetric soil water content (θ) is fundamental to agriculture because its spatiotemporal variation in soil affects the growth of plants. Unfortunately, the universally accepted thermogravimetric method for estimating volumetric soil water content is very labour intensive and time‐consuming for use in field‐scale monitoring. Electromagnetic (EM) induction instruments have proven to be useful in mapping the spatiotemporal variation of θ. However, depth‐specific variation in θ, which is important for irrigation management, has been little explored. The objective of this study was to develop a relationship between θ and estimates of true electrical conductivity (σ) and to use this relationship to develop time‐lapse images of soil θ beneath a centre‐pivot irrigated alfalfa (Medicago sativa L.) crop in San Jacinto, California, USA. We first measured the bulk apparent electrical conductivity (EC_a – mS/m) using a DUALEM‐421 over a period of 12 days after an irrigation event (i.e. days 1, 2, 3, 4, 6, 8 and 12). We used EM4Soil to generate EM conductivity images (EMCIs). We used a physical model to estimate θ from σ, accounting for soil tortuosity and pore water salinity, with a cross‐validation RMSE of 0.04 cm³/cm³. Testing the scenario where no soil information is available, we used a three‐parameter exponential model to relate θ to σ and then to map θ along the transect on different days. The results allowed us to monitor the spatiotemporal variations of θ across the surveyed area, over the 12‐day period. In this regard, we were able to map the soil close to field capacity (0.27 cm³/cm³) and approaching permanent wilting point (0.03 cm³/cm³). The time‐lapse θ monitoring approach, developed using EMCI, has implications for soil and water use and management and will potentially allow farmers and consultants to identify inefficiencies in water application rates and use. It can also be used as a research tool to potentially assist precision irrigation practices and to test the efficacy of different methods of irrigation in terms of water delivery and efficiency in water use in near real time.     

父母本不同行距配置对昆虫授粉效率的影响

为探讨昆虫为杂交大豆授粉的行为,提高授粉效率,以大豆细胞质雄性不育系JLCMS34A和保持系JLCMS34B为材料,研究父母本3种行距配置(T1、T2、T3)对昆虫授粉行为及产量构成的影响。结果表明:行距配置T2条件下昆虫授粉效率最高,母本单株粒数最多,为45.98个(2011年),与T1、T3差异达到显著水平,T3配置授粉效率最差,单株粒数最少,为32.06个(2012年),与T1、T2差异达到极显著水平。在吉林省洮南地区适当缩小父母本行距,增加母本间行距可有效促进昆虫授粉效率,提高结实率。     

重庆市荣昌区饮用水源地环境评估与管理对策

为保障城镇居民饮水安全,从水源地环境管理状况和水源地水质评价2个方面对环境状况进行评估。结果表明,虽然高升桥饮用水源地综合评估结果为优秀,水质状况较好,但在水源地管理方面仍存在较多问题。针对监测能力、监管能力不足和群众环保意识薄弱等问题,提出了相关对策。     

Transgenic sorghum with suppressed synthesis of kafirin subclasses: Effects on flour and dough rheological characteristics

Arising from work showing that conventionally bred high protein digestibility sorghum types have improved flour and dough functionality, the flour and dough properties of transgenic biofortified sorghum lines with increased protein digestibility and high lysine content (TG-HD) resulting from suppressed synthesis of several kafirin subclasses, especially the cysteine-rich γ-kafirin, were studied. TG-HD sorghums had higher flour water solubility at 30 °C (p < 0.05) and much higher paste viscosity (41% higher) than their null controls (NC). TG-HD doughs were twice as strong as their NC and dynamic rheological analysis indicated that the TG doughs were somewhat more elastic up to 90 °C. CLSM of doughs and pastes indicated that TG-HD had a less compact endosperm protein matrix surround the starch compared to their NC. The improved flour and dough functional properties of the TG-HD sorghums seem to be caused by reduced endosperm compactness resulting from suppression of synthesis of several kafirin subclasses which modifies protein body and protein matrix structure, and to improved protein-starch interaction through hydrogen bonding specifically caused by reduction in the level of the hydrophobic γ-kafirin. The improved flour functionality of these transgenic biofortified sorghums can increase their commercial utility by complementing their improved nutritional quality.