Effects of best management practices on dry matter production and fruit production efficiency of oil palm

Enhancing dry matter production with higher partitioning to fruit bunches is important for sustainable intensification of oil palm. A series of best management practices including site-specific nutrient management, canopy management, and harvesting has been developed for oil palm plantations. However, the effects of these practices on dry matter production and partitioning, and how the effects vary with climatic and soil conditions of plantation sites, remain largely unknown. We established a four-year field trial including 30 paired commercial blocks across Sumatra and Kalimantan, Indonesia. The paired treatments included site-specific best management practices, and standard estate practices as the control. The annual production of aboveground dry matter was 30.0 ± 0.5 t ha⁻¹ yr⁻¹ (mean ± se) under best management practices, higher than 28.8 ± 0.5 t ha⁻¹ yr⁻¹ under standard estate practices. The bunch index, an indicator of the fruit production efficiency, increased by 12% under best management practices compared to standard estate practices. Partitioning of dry matter to the fronds decreased by 8% under best management practices, compared to standard estate practices. The positive effect of best management practices on the annual production of total aboveground dry matter was stronger in the plantation site with higher annual rainfall. These results are useful for optimizing management practices to improve sustainable intensification of oil palm.     

基于PID的饲料制粒调质温度控制系统设计与试验

为解决颗粒饲料在制粒过程中调质温度依赖人工辅助控制问题，该研究设计了基于PID控制算法的调质温度控制系统。采用开环阶跃响应法建立电动比例调节阀与调质温度之间的控制模型。为了得到最优的PID控制参数(比例系数K_p、积分系数T_i、微分系数T_d)，通过Simulink仿真试验对比了Ziegler-Nichols整定法、衰减曲线法和临界比例度法的PID响应曲线，确定PID最优控制参数为K_p=52.7,T_i=6.4,T_d=1.6。对小型制粒机调质温度控制系统进行试验，选用哺乳母猪配合粉料，调质温度分别设定为75、80和85℃，稳定后的调质温度均能维持在设定范围内；选取调质温度为80℃进行稳定性试验，每1 min记录调质温度，整个试验过程中调质温度基本稳定在(80±1)℃范围内，调质温度平均相对误差小于1%，调质温度变异系数小于0.5%，系统温度控制稳定，可自动采集制粒生产数据，实现了制粒过程中调质温度的快速响应和实时控制。研究结果可为颗粒饲料制粒机的自动化控制提供参...     

干播湿出技术对不同土壤质地棉花生长和产量的影响——以阿拉尔垦区为例

本试验在阿拉尔垦区选取不同质地土壤地块，研究干播湿出技术对棉花生长发育和产量的影响。结果表明：不同土壤质地干播湿出模式下棉花出苗率差异不大，整体出苗情况良好；沙质土棉田株高高于壤质土和黏质土，初期差异明显，后期差异逐渐变小；不同土壤质地棉田果枝薹数差异不明显，生育后期壤质土铃数最多；土壤碱解氮和有效磷的含量为壤质土>黏质土>沙质土，土壤速效钾的含量为黏质土>壤质土>沙质土，土壤含盐量为黏质土>沙质土>壤质土，棉花产量为壤质土>沙质土>黏质土。综合来看，壤质土为干播湿出技术的应用提供了最有利的条件，可促进棉花生长发育和对土壤速效养分的吸收，从而获得较高产量。     

Impact analysis of climate data aggregation at different spatial scales on simulated net primary productivity for croplands

For spatial crop and agro-systems modelling, there is often a discrepancy between the scale of measured driving data and the target resolution. Spatial data aggregation is often necessary, which can introduce additional uncertainty into the simulation results. Previous studies have shown that climate data aggregation has little effect on simulation of phenological stages, but effects on net primary production (NPP) might still be expected through changing the length of the growing season and the period of grain filling. This study investigates the impact of spatial climate data aggregation on NPP simulation results, applying eleven different models for the same study region (∼34,000 km²), situated in Western Germany. To isolate effects of climate, soil data and management were assumed to be constant over the entire study area and over the entire study period of 29 years. Two crops, winter wheat and silage maize, were tested as monocultures. Compared to the impact of climate data aggregation on yield, the effect on NPP is in a similar range, but is slightly lower, with only small impacts on averages over the entire simulation period and study region. Maximum differences between the five scales in the range of 1–100 km grid cells show changes of 0.4–7.8% and 0.0–4.8% for wheat and maize, respectively, whereas the simulated potential NPP averages of the models show a wide range (1.9–4.2 g C m⁻² d⁻¹ and 2.7–6.1 g C m⁻² d⁻¹ for wheat and maize, respectively). The impact of the spatial aggregation was also tested for shorter time periods, to see if impacts over shorter periods attenuate over longer periods. The results show larger impacts for single years (up to 9.4% for wheat and up to 13.6% for maize). An analysis of extreme weather conditions shows an aggregation effect in vulnerability up to 12.8% and 15.5% between the different resolutions for wheat and maize, respectively. Simulations of NPP averages over larger areas (e.g. regional scale) and longer time periods (several years) are relatively insensitive to climate data aggregation. However, the scale of climate data is more relevant for impacts on annual averages of NPP or if the period is strongly affected or dominated by drought stress. There should be an awareness of the greater uncertainty for the NPP values in these situations if data are not available at high resolution. On the other hand, the results suggest that there is no need to simulate at high resolution for long term regional NPP averages based on the simplified assumptions (soil and management constant in time and space) used in this study.     

长白种猪优化选配减少近交畸形的研究

以华南某1 500头规模种猪场2009年到2010年1 502窝长白猪分娩信息进行优化、选配减少近交畸形的研究,结果显示血缘选配优化时将近交系数控制在1%比3%效果明显,平均产活仔数从10.39头/窝提高到10.46头/窝(P＞0.05),畸形率从10.30%下降到4.79%(P＜0.01);对其中402窝出现畸形仔猪...     

铣工安全生产技术的研究

铣工是操纵铣床进行生产的劳动者,在铣床工作时,铣刀、工件、切屑和装夹工作的夹具等,都有可能使铣工受到伤害。本研究用于指导铣工岗位员工对危害因素带来的风险实施有效控制。     

杂交稻新品种泸优637高产制种技术

介绍了杂交稻新品种泸优637高产制种技术：制种基地选择与隔离，合理安排父母本播种差期，构建父母本高产群体，采取综合措施提高异交结实率，严格去杂去劣，做好病虫防治，确保种子质量。     

甘蔗快锄低砍技术增产效应

甘蔗快锄低砍是临沧市近几年来在甘蔗生产中推广的一项新技术,2008/2009年榨季,市甘蔗技术推广站先后在幸福、耿马、华侨和勐永4个蔗区,选择不同田块、不同种植类型、不同熟期和不同茎型的10个甘蔗品种进行对比调查测定,结果显示,应用快锄低砍技术砍收甘蔗,平均每公顷比传统齐地面砍收或略高于地面砍收方法多收甘蔗4010.25kg,扣除额外增加的投入,蔗农可增收822.11元。     

我国芒果标准现状与标准化生产对策分析

介绍我国芒果的标准现状，分析芒果标准化生产存在的问题，并提出如何提高标准化生产的对策。     

Structural and Biometric Characterization of Nothofagus betuloides Production Forests in the Magellan Region,Chile

Summary

This study, in die Chilean Magellan Region, undertook the structural and biométrie characterization of Nothofagus betuloides (Mirb.) Blume (coihue de Magallanes) production forests to provide information for sustainable forest management. Six locations were surveyed, five on the continent and one on Tierra del Fuego Island. A total of 6,102 ha were photointerpreted and then checked and described in the field according to their location, environmental characteristic, and vegetation type. The degree of disturbance, stage of development, status of regeneration, and composition and cover of the understory were also described. From the surveyed locations, a total of 3,807 ha were production forests of which a 76% area had Nothofagus pumilio (lenga) and N. betuloides mixed forests. The remaining areas (24%) were pure N. betuloides forests. Nondisturbed, old-growth forests covered 47% of the surveyed area. The remaining area (53%) had some disturbance. In the nondisturbed forests, mean volume stocks were 438 m³ ha^-1, and in disturbed forests, mean volume stocks were 316 m³ ha^-1.