蔬菜移栽钵苗检测与缺苗补偿系统设计与试验

为解决蔬菜穴盘苗全自动移栽机因穴盘缺苗、取投苗失败等因素导致的漏栽现象，设计了基于多传感器的钵苗检测及缺苗补偿系统(补苗系统)。补苗系统作为独立功能模块，包括补苗装置、钵苗检测单元和控制系统，使用反射型光纤传感器和激光传感器联合检测的方法，对分行苗杯定位和苗杯内钵苗进行识别。利用光纤传感器分别对辣椒、番茄、甘蓝钵苗进行多高度检测试验，以获取光纤传感器最佳检测高度和最佳缺苗判定阈值。设计了自动补苗装置，并对补苗过程进行运动学分析。使用触摸屏、PLC、EM253位置模块等控制元件设计了控制系统，实现整机及补苗系统的控制。对补苗系统进行不同移栽频率下的性能对比试验，试验结果表明：在单行栽植频率分别为60、70、80 株/min时，补苗系统识别成功率分别为98.15%、98.15%、97.69%，移栽机平均漏栽率分别为1.85%、2.31%、2.31%，比未启用补苗系统时漏栽率分别降低了14.59、14.36、15.52个百分点，为进一步提高蔬菜移栽作业品质提供参考。     

Site of leaf origin affects how mixed litter decomposes

Recent studies have demonstrated that mass loss, nutrient dynamics, and decomposer associations in leaf litter from a given plant species can differ when leaves of that species decay alone compared to when they decay mixed with other species’ leaves. Results of litter-mix experiments have been variable, however, making predictions of decomposition in mixtures difficult. It is not known, for example, whether interactions among litter types in litter mixes are similar across sites, even for litter mixtures containing the same plant species. To address this issue, we used reciprocal transplants of litter in compartmentalized litterbags to study decomposition of equal-mass litter mixtures of sugar maple (Acer saccharum Marshall) and red oak (Quercus rubra L.) at four forest sites in northwestern Connecticut. These species differ significantly in litter quality. Red oak always has higher lignin concentrations than maple, and here C:N is lower in oak leaves and litter, a pattern often observed when oak coexists with maple. Overall, we observed less mass loss and lower N accumulation in sugar maple and red oak litter mixtures than we predicted from observed dynamics in single-species litterbags. Whether these differences were significant or not depended on the site of origin of the leaves (P<0.02), but there was no significant interaction between sites of decay and the differences in observed and predicted decomposition (P>0.2) . Mixing of leaf litter types could have significant impacts on nutrient cycling in forests, but the extent of the impacts can vary among sites and depends on the origin of mixed leaves even when the species composition of mixes is constant.     

棉花移栽机旋转式取苗机构的运动学分析及虚拟试验

为了实现棉花移栽自动取苗,针对棉花基质苗茎秆抗拉力远大于取苗力的特点,该文提出高阶混合变性椭圆齿轮行星系夹苗式取苗机构,并建立该机构的运动学数学模型,分析夹苗式取苗工作的运动目标,编写机构优化分析软件,确定一组机构参数:啮合齿轮中心距58 mm,第1级基椭圆的偏心率为0.2,二阶变形椭圆齿轮的主变形系数0.9,第2级基椭圆的偏心率为0.14,一阶变形椭圆齿轮的主变形系数0.18,初始时刻太阳轮标线的安装角为13π/18、行星架OA边与太阳轮标线的夹角为π/2、中间轴A上安装的第2中间轮与第1中间轮标线的夹角为7π/18、行星架AB边相对与第2中间轮标线夹角为35π/36、取苗爪BE边相对于第1行星轮标线夹角π/6、取苗爪BE边与BT边夹角7π/18、取苗爪BT边长度150 mm,工作轨迹的取苗段与苗箱夹角91°、取苗过程行星架转角36°、取苗过程苗与钵盘不干涉、取苗过程取苗爪摆角5°、入苗段与取苗段轨迹夹角为85°、投苗角76°、两取苗爪之间最小距离49 mm。机构的虚拟试验表明,该型取苗机构的工作轨迹和理论计算吻合,满足夹苗式取苗工作要求,取苗爪在取苗段速度较大利于快速取苗,周期速度曲线平滑,该研究结果为棉花基质育苗移栽自动取苗提供了参考。     

吊杯式栽植器的优化设计及试验

针对目前吊杯式移栽机在移栽过程中出现的膜上穴口尺寸过大、栽植器容易撕膜、刮膜等问题,从栽植器的结构参数和分析特征系数入手,对于膜上穴口尺寸进行了研究。通过Pro/E建立栽植器的三维模型并进行优化设计与制造,对8 cm×8 cm和6 cm×6 cm口径的2种栽植器进行了田间对比试验,分析了其对膜上穴口尺寸的影响程度。然后通过变换传动比改变运动特征系数来研究运动特征系数对膜上穴口尺寸的影响规律。试验表明通过改进栽植器的结构,膜上横向尺寸较改进前平均降低了约45.3%;膜上纵向尺寸较改进前平均降低了17.9%。当运动特征系数从小变大时,膜上穴口平均值表现为先减小后增大,在运动特征系数为1.238时膜上穴口尺寸最小,说明运动特征系数存在最优值。改进栽植器机构后的试验结果为:株距的平均值维持在40 cm左右,漏苗率为1.07%,伤苗率为0.71%,直立度合格率为92.6%。当运动特征系数为1.238时,穴口纵向尺寸平均值为71 mm,横向尺寸平均值为18.5 mm,均为最小值。故对于2ZP型移栽机,运动特征系数取1.238为宜。该研究为吊杯式移栽机改进设计和性能优化提供参考。     

水稻超稀植栽培丛插基数与插秧密度的研究

试验研究了稻作超稀植栽培下 ,丛插基数和插秧密度对产量诸构成因素的影响。结果表明 :超稀植时 ,插秧密度对分蘖率、结实率的影响不显著 ,而插秧基数成为增产的限制性因子 ;丛插基数和插秧密度具有密切的互补性 ,插秧密度 2 9 7cm× 19 8cm ,丛插基数为 1株 /穴的处理更有利于产量的增加 ;插秧密度相同而行株距有差异的两组处理相比 ,宽行距的处理更能协调群体的光能利用和改善通风能力 ,从而提高产量。     

哺乳动物胚胎分割发展现状及展望

本文系统综述了国内外哺乳动物胚胎分割的当前水平和今后发展趋势。对影响分割胚存活率的若干因素、分割胚的冷冻、人工嵌合体的制作、胚胎性别鉴定及卵核移植等方面的研究进展也作了简要介绍。     

穴盘苗移栽机自动取喂系统的设计与试验

该文针对新疆地区吊篮式移栽机手工喂入效率低的问题,设计了穴盘苗移栽自动取喂系统。该系统采用穴盘步进移位机构提供穴盘的横向和纵向移位,由翻转摆位式取苗机械手进行取苗和穴盘苗的转移,利用柔性链输送喂入机构对穴盘苗逐个投放,能够对穴高45 mm、上边宽31.75 mm、下边宽13 mm的吸塑成型的软穴盘苗进行自动取苗并向两个栽植器投苗。整个系统由PLC（programmable logic controller）程序控制,采用气压驱动,工作气压0.5～0.8 MPa,耗气量60.65 L/min,单组取喂系统结构独立,质量小于110 kg,不增加原有移栽机地轮负荷,即能与新移栽机配套生产,也能对现有移栽机进行自动化改造。系统中穴盘步进移位机构在柔性链输送喂入机构的侧上方倾斜放置,使穴盘上表面与水平面的夹角105°,缩小了机器水平占用空间。采用苗龄58 d的"红安6号"辣椒苗进行室内取苗试验,试验结果显示,系统取喂苗总可靠率达98.92%,平均基质损失质量9.26%,取喂速度达70株/min,未见明显伤苗,能够满足设计要求。     

定植孔密封方式对土壤水热盐及番茄苗存活率的影响

为了提高河套灌区盐碱地番茄移栽成活率,以番茄定植孔采用土封孔为对照,监测了沙封孔、不封孔株间和根际的土壤水分、土壤盐分、土壤温度及番茄幼苗的生长状况。结果表明,不同处理株间土壤水分、土壤盐分、土壤温度无显著差异。沙封孔、不封孔与土封孔相比,根际0～10cm土层土壤水分降低了11.73%和14.80%,≥10～20cm土层降低了9.60%和13.64%;根际5cm土层最高温度降低了1.2和3.6℃,日均温降低了1.6和2.2℃;根际0～10cm土层土壤盐分降低了19.11%和24.84%,≥10～20cm土层降低了11.48%和19.67%。沙封孔、不封孔番茄幼苗移栽成活率较土封孔提高了20.57%和19.40%。河套灌区盐碱地地膜覆盖栽培番茄,定植时采用沙封孔或不封孔,可降低根际土壤水分及土壤温度,阻碍盐分表聚于根际土壤,提高了番茄幼苗的移栽成活率,该研究为河套灌区盐碱地种植番茄提供指导。     

The effect of nitrogen,volume of media,plant density and module shape on the growth of asparagus seedlings

There were three experiments in which the seedlings were raised in media contained in plastic cells. In Experiment 1, 150 or 200 mg l^?1 N were applied in factorial combination with cell volumes of 20, 32 or 50 cm³, There were 6 successional harvests. All cells were 7.5 cm deep and cylindrical in shape. Experiment 2 compared these 3 cell volumes at densities of 983, 1532 or 2440 plants per m². Cell diameters restricted the 50-cm³ cell to the 983, and the 32-cm³ cell to the 983 and 1532 plants per m² densities. 200 mg l^?1 N increased shoot growth, but not root growth. This increase in shoot growth was not considered advantageous. Seedling growth increased with increases in cell volume, but there were no responses to changes in plant density. Experiment 3 compared a cell having an inverted pyramid shape with a cylinder. The cylinder, despite holding 20% less media, produced the larger seedlings.     

Suitability of wood fiber substrates for production of vegetable transplants II.: The effect of wood fiber substrates and their volume weights on the growth of tomato transplants

The influence of wood fiber substrates (WFS) and their volume weights (VW) on the growth of tomato transplants (Lycopersicon lycopersicum (L.) Karst. ex Farw.) were examined. No significant differences were observed for the absolute and relative growth rate of tomato transplants cultivated in WFS as compared to white peat (WP). Particularly in WFS plants showed a well developed root system. When the tomato transplants were cultivated in spring increases of VW led to a reduction of root growth, but no significant differences were observed for other plant parameters. In summer differences between weakly and strongly compacted substrate treatments for fresh mass of leaf and stem for both WFS were found. The coarse WFS also showed a significant difference in leaf area for these two treatments. Weakly compressed substrate had a faster decrease of matric potential in summer.WFS are suitable for cultivation of vegetable transplants and are a good alternative for peat-based substrates. When filling containers, moderate compression of WFS is recommended.