滩羊土——草——畜系统中的微量元素及其意义

甘肃景泰滩羊典型产区草地土壤中含有Ｂｅ、Ｐｂ、Ｔｉ、Ｂａ、Ｍｎ、Ｇａ、Ｃｒ、Ｎｉ、Ｖ、Ｃｕ、Ｚｒ、Ｃｏ、Ｓｒ、Ｙ、Ｙｂ等１５种微量元素。草地混合牧草吸其中的１３种,其中Ｙｂ显著减少,缺少了Ｂｅ和Ｃｏ。羊毛中微量元素的种类和含量变化很大并且复杂。滩羊成年母羊毛中只含Ｐｂ、Ｔｉ、Ｍｎ、Ｃｕ等４种元素,而二毛期即１月龄羔羊毛中含有Ｂａ、Ｐｂ、Ｔｉ、Ｍｎ、Ｃｒ、Ｎｉ、Ｃｕ、Ｚｒ、Ａｇ、Ｚｎ、Ｓｒ、Ｍｏ和Ｙ     

高水肥密植条件下大豆地上部干物重变化动态

在高施有机肥、地下亚表层灌水、窄行密植栽培模式下,对大豆合农60及对照品种垦丰16地上部干物质变化动态进行分析。结果表明:合农60荚干重增加明显,后期干物重积累迅速。在高水肥和小垄密植栽培条件下,窄行密植品种间存在差异,合农60为抗倒伏,适合于窄行密植的高产品种。     

再生稻空间直取大偏移轮系宽窄行分插机构设计与试验

为了解决再生稻生产过程中,收获机履带碾压头季稻稻桩的问题,本文从机械栽植角度入手,在单位种植面积有效株数一定的条件下,通过合理增大栽植行距以增大履带行走行距。提出一种可实现大偏移、直取秧和小侧向穴口移栽轨迹的空间行星轮系分插机构。首先,结合栽植农艺规划宽窄行移栽轨迹并确定其上若干关键位置与姿态,建立了空间2R开链机构3精确位姿空间几何约束设计方程,采用同伦算法进行求解;然后,基于求解参数拟合、优化得到开链机构输入轴与输出轴相对角位移曲线,确定机构传动比与非圆齿轮节曲线,复演得到满足移栽要求的空间轨迹;最后,通过依附非圆齿轮副将开链机构两转轴运动耦合,设计得到一种由平面非圆齿轮与斜齿轮组合传动的轮系式再生稻宽窄行分插机构,并进行虚拟仿真与样机试验,结果表明样机实际运动轨迹姿态与理论设计基本一致;取苗至推苗横向偏移量ΔS1为65.59mm、侧向推苗角γ1为16.13°、侧向穴口宽度ΔS3为23.69mm,满足再生稻宽窄行移栽要求,验证了轮系式宽窄行分插机构设计的可行性。     

季节性干旱丘区稻田麦秸覆盖的节水效应研究

2004~2005在季节性干旱的丘陵地区对麦秸覆盖稻作的节水效应进行了研究。结果表明:在该生态区采用旱育秧技术,培育多蘖壮秧,旋耕后采用宽窄行移栽,田间苗数达到225×104.hm-2时用等面积的小麦秸秆全量覆盖宽行的技术模式,可节水30.04%,增产5.88%,水分生产率提高0.52 kg.m-3,灌溉水的水分生产率提高1.24 kg.m-3;全程节本增效1129.70元.hm-2。稻田麦秸覆盖的节水效果与秧苗栽插方式有关,与麦秸还田量成正相关;翻耕比免耕节水、高产高效。     

Eleven years of integrated weed management: long‐term impacts of row spacing and harvest weed seed destruction on Lolium rigidum control

Long‐term research aimed to determine whether narrow row spacing and harvest weed seed destruction, in combination with herbicide use, would be sufficient to drive a Lolium rigidum population to extinction. A trial was run from 1987 to 2013, with treatments including crop row spacings of 9, 18, 27 or 36 cm and crop residue burning or retention. Herbicides were applied to reflect regional practices. The initial trial design was randomised, but treatments were maintained in each plot over the following years. Lolium rigidum seed production at harvest was assessed from 2003 to 2013. Average crop yield was higher in the unburnt plots (1638 kg ha^?1) than the burnt plots (1530 kg ha^?1) and greater at narrow row spacing, with an average yield of 1658, 1637, 1548 and 1492 kg ha^?1 in the 9‐, 18‐, 27‐ and 36‐cm spacings. Lolium rigidum seed at harvest was reduced in the burnt plots (57 seeds m^?2) compared with the unburnt plots (297 seeds m^?2) and was reduced at narrow row spacing, with an average of 58, 78, 223 and 333 seeds m^?2 in the 9‐, 18‐, 27‐ and 36‐cm row spacings. By 2013, L. rigidum seed production was reduced to an average of 0 seeds m^?2 in the narrow row spacing, burnt plots.     

挪威云杉种源及家系种子播种品质的研究

通过对引进的芬兰挪威云杉5个种源和窄冠垂枝挪威云杉10个家系种子播种品质的方差分析和聚类分析研究表明,挪威云杉种源和窄冠垂枝挪威云杉家系种子净度达98％以上。种子的播种品质与地理分布和起源有关。由北向南种子的千粒重增加、发芽率提高、死亡率下降。另外,天然起源的种子播种品质低于种子园的种子。窄冠垂枝挪威云杉因天然分布区域极为狭窄、种群规模过小,导致由其它因素造成的未萌发百分率高。     

Heritability of, and genetic correlations among, forage and seed yield traits in Ladino white clover

Sixteen white clover genotypes and their half-sib progenies were grown in pure stand. Each clover progeny was also grown in a mixed stand that also included three grass varieties of different species. Dry matter (DM) yield was measured over 2 years and seed yield at the second year. Competitive ability of clover families was defined as the ratio between mixed stand and pure stand for clover DM yield. Narrow-sense heritability from parent-offspring regression of pure stand data was high to moderate (h²0.50) for DM yield, seed yield and most of their components. Persistence as predicted by stolon density showed negative genetic correlations with seed yield (r_g= -0.70) and DM yield (r₂= -0.60), whereas seed yield and DM yield tended towards a negative correlation (r₂=0.45). Sizes of different vegetative or reproductive organs were generally correlated positively. Evidence was provided that the set of parent genotypes represents well the genetic variation available within the Ladino gene pool. The results highlighted the difficulty of combining relatively short-term DM yield, persistence and seed yield into a unique plant type. Differences in competitive ability emerged only in the second year, better ability being related mainly to petiole length among the traits assessed in pure stand.     

等壳碾压混凝土重力坝层间抗滑稳定可靠度分析

针对以有限元为基础分析碾压混凝土重力坝层间可靠度其功能函数不能显式表达的特点,采用响应面法、JC法、窄界限法原理相结合的可靠度计算方法。由三维非线性有限元对等壳水电站碾压混凝土重力坝各随机变量分位点值的计算结果,采用抗剪断公式构建该电站非溢流坝段层面的功能函数,求得响应面方程,并应用JC法和窄界限法计算层间单元可靠度指标及层间体系可靠度指标,进一步分析材料的变异系数对体系可靠度的影响。结果表明,φ是影响体系可靠度指标的最敏感因子,碾压各层β值一般为4.16～5.70,层间体系可靠度β'为4.12,满足工程要求。该方法计算效率高,实用性强,用于碾压混凝土重力坝层间抗滑稳定可靠度分析是可行的,值得推广。     

端部效应修正螺旋窄槽理论应用于液膜机械密封的解析法

针对螺旋槽上游泵送机械密封的研究和设计过程中,利用未考虑修正因素的近似解析法所得结果与试验结果偏差进行比较,为准确、高效地解析计算螺旋槽上游泵送机械密封的性能,考虑液体进入螺旋槽时会产生压力损失的“端部效应”,对螺旋槽根处的压力进行了修正,获得了修正后的液膜压力分布近似解析表达式和密封的开启力.并将开启力与未修正的近似解析计算结果、数值模拟结果和试验结果进行了比较.结果表明:修正后的近似解析计算结果与数值模拟结果和试验结果基本吻合,当密封处于低压差工况时,与数值模拟结果的平均相对误差为19％,最大相对误差为62％,与试验结果的平均相对误差为86％,最大相对误差为155％;当密封处于高压差工况时,与数值模拟结果的平均相对误差为19％,最大相对误差为25％.研究结果可为上游泵送机械密封等液膜润滑机械密封的研究、设计和应用提供参考.     

不同栽培方式对大豆产量及构成因子的影响

为了提高大豆产量,试验设置2种配套栽培模式处理,研究45cm窄行密植栽培模式和65cm垄作栽培模式对大豆产量及其构成因子的影响,并对经济效益进行分析。结果表明:垄作栽培下,黑河36的株荚数、株粒数、荚粒数均高于窄行密植栽培模式下的合农60。合农60窄行密植栽培模式产量为3 615kg·hm-2,黑河36垄作栽培模式产量为2 865kg·hm-2,2种栽培模式下产量差异达到极显著水平。窄行密植栽培模式较垄作栽培模式增产750kg·hm-2,增产率达到26.18%,增收效益为3 000元·hm-2。