鲁枣系列枣新品种

山东省果树研究所利用实生选种和地方选优方法，选育出用途多样、熟期配套、优质、早实丰产、抗逆性强的鲁枣系列枣新品种14个，全部通过省级审定，其中11个品种通过国审。鲁枣系列新品种在重要经济性状上有显著改进，既丰富了枣种质资源，又为产业发展提供了技术支撑。     

面向数控加工系统的3D打印切片算法与分区扫描策略

为实现大型农机零部件的快速修复与更换,该文针对3D打印协同数控成形大型零件中的折线拐点金属过堆积、工件翘曲变形、层厚难以实时调整等问题,提出数控系统与电子束成形相结合的3D打印切片算法与分区扫描策略。为提高切片速度,实现成形过程中的层厚实时调整,采用反向光线追踪算法对三维模型渲染切片,通过MS(marching squares)算法提取二值图像的坐标序列,快速获取指定层的轮廓坐标;为避免成形过程中电子枪运行速度不均匀引起的金属过堆积现象,选用B样条基函数对轮廓数据进行曲线插值,结合数控系统的曲线插补命令,实现恒定线速度成形。针对大型零件在成形过程中的变形问题,采用六边形分区与平行线变角度扫描技术,根据各分区图案的形心欧式距离规划扫描顺序,实现变形控制。结果表明:采用非均匀有理B样条曲线和直线分段插值后,拟合曲线对原始多重曲面截线的逼近误差范围与切片数据相比减少了30%。选用网格数量为1 483 132的STL(stereolithography)模型进行效率测试,该算法切片用时90 s,与商用软件Magics15.01切片相比用时减少了34.6%,与开源软件Cura15.06切片相比用时减少了31.4%,研究结果可为大型零件成形过程中的层厚动态调整及变形控制等提供新的思路。     

Human-altered and human-transported (HAHT) soils in the U.S. soil classification system

ABSTRACT

Human-altered and human-transported (HAHT) soils are widespread across the globe and are concentrated near where people live and work. Although some of the HAHT soils are significant because they can be hazardous to human, animal, and plant health, most are not mapped or classified to the same extent as agricultural soils. The purpose of this article is to discuss the occurrence, types, and importance of HAHT soils and to document the historical and proposed classification of HAHT soils in Soil Taxonomy. There are two main forms of materials that define HAHT soils: human-altered soils formed in human-altered materials (HAM) from the soil surface to 50 cm (or to bedrock if shallower) or more and human-transported soils formed in human-transported materials (HTM) from the soil surface to 50 cm (or to bedrock if shallower) or more. The HAHT soils mainly occur in urban areas, transportation corridors, mined lands, landfills, filled shallow water, and agricultural areas on anthropogenic landforms. Hazards include danger from radioactivity, pollution, content of hazardous artifacts, or presence on unstable landforms that may fail during heavy rains or earthquakes. The HAHT soils are extensive, and their extent is growing. In the past, few HAHT soils were described or classified adequately because the U.S. Soil Taxonomy system was established for agricultural and other naturally occurring soils. However, HAHT soils are now being recognized and classified in many soil classification systems at very high levels. A new soil order is proposed for U.S. Soil Taxonomy that would include the most obvious profoundly and intentionally altered HAHT soils. A discussion and justification is given for an unofficial proposal. Input will be collected from international groups of scientists, and modifications of the unofficial proposal are expected. The long-term result of establishing a new soil order will be to enable proper classification, allocation, and mapping of HAHT soils worldwide.     

基于PLSR-BP复合模型的红壤有机质含量反演研究

对红壤地区土壤有机质进行快速预测,以满足智慧农业与精准施肥的需要。以江西省奉新县北部为研究区域,采用1 km×1 km标准格网划分研究区进行采样,共得到红壤样本248个。对土壤光谱进行了包含分数阶导数在内的3种数学变换方法,将经过P=0.01显著性检验的波段用于模型的构建,选用偏最小二乘回归(PLSR)和BP神经网络建立土壤有机质含量预测模型。结果表明:当对红壤光谱数据进行1.5阶导数变换后再使用PLSR-BP复合模型对土壤有机质含量进行预测时的结果为最优,训练集R~2=0.89,RMSE=4.68g·kg~(-1),验证集R~2=0.87,RMSE=5.55g·kg~(-1),RPD=2.75。1.5阶导数对红壤光谱数据的变换能够更好地突出与有机质相关的特征信息,有助于其含量预测。PLSR-BP复合模型预测精度优于单一模型,能够较好地预测红壤有机质含量,为精准农业快速监测红壤有机质含量提供了新的途径。     

‘热引19号’坚尼草选育研究报告

1998年从澳大利亚引入坚尼草TD58(Panicum maximum‘TD58')后,相继完成适应性评价、品种比较试验、区域试验和生产试验,2007年选育而成‘热引19号'坚尼草(P.maximum'Reyin NO.19')。结果表明:该品种年均干草产量达21753.02 kg·hm~(-2),种子年均产量为800.05 kg·hm~(-2),营养价值适中,且耐低温、耐荫、耐旱、花期晚,综合性状均优于对照品种,是适合于我国南方热带亚热带地区推广种植的牧草新品种。     

蓝桉、直干桉重要材性性状的遗传参数和预期增益

在种子园育种区4个区组内,从蓝按和直干按中各抽30个家系对它们的纤维长度、木材密度的遗传力、遗传相关和遗传增益作了估算.蓝按纤维长度和木材密度的单株遗传力分别为,0.6745±0.0746和0.3546±0.1010;直干按两性状的遗传力分别为0.3416±0.1011和0.0670±0.0850.两树种的纤维长度与木材密度、树高和胸径的遗传相关系数均为正值,而木材密度与树高和胸径的遗传相关系数都是负数.为这两树种提出了选择的主要性状、选择方法和标准,还为高世代育种应注意的事项作了建议.     

南昌观赏树种的选择与应用

从南昌市的自然概况、植被类型、生态环境等角度论述了绿化树种选择的原则和方法。并把园林绿化树种分为骨干树种、高档树种和基调树种3种不同的类型，为城乡园林绿化树种选择提供借鉴和参考。     

长白落叶松生长性状早晚相关及早期选择的研究

本文对３０年生９０株人工长白落叶松树干解析生长变异及早期预测进行了研究，结果表明，树高、胸径、材积的变异随着年龄增大而减小，１４～１８龄是生长变异由剧烈分化到趋向稳定的转折年龄，此时树高、胸径、材积等的幼龄至成熟龄相关达极显著水平，选择效率也处在较高水平，确定长白落叶松早期选择年龄为１４年。     

Tree planting in Tigray, Ethiopia: the importance of human disease and water microdams

We examine the decision to plant trees and level of tree planting for two sites, public microdam areas and household agricultural land, and two species groups in Tigray, Ethiopia. Both sites are not perfect substitutes, as they vary with respect to distance from the household and tenure security. The role of permanent pooled water irrigation microdams to tree planting is important but unknown, because water borne diseases, which may influence household income and productivity, are thought to be enhanced by the dams. We find both disease and microdams to be important predictors to tree planting. Disease seems more important in determining whether households plant at all, and less important in the level of planting for those that do plant. For example, disease increases the probability of planting both eucalyptus and other species groups on household-own land, but households suffering from malaria plant higher-cost eucalyptus trees with lower probability at both sites, while planting of other lower-cost species increases at dam sites where other villagers can monitor the trees. We also establish a connection between planting and agricultural residues, finding a strong substitution effect on own-land. Microdam access and age are also important. Households living nearer to dam sites will plant both species groups there with higher probabilities, but the decision to plant on agricultural own-land is not affected. For older dams with more developed irrigation, households are more likely to grow crops rather than plant trees on their own land, but they plant more trees at the dam sites. This revised version was published online in June 2006 with corrections to the Cover Date.