船式拖拉机气层减阻研究

为预估不同含水率的水田土壤气层减阻所需通气量,通过流变仪测得相应的水田土壤参数,并构建仿真模型进行了相应仿真试验.在试验过程中,分析了不同通气量下的船底气层覆盖情况以及不同通气量下的阻力变化,解释了其减阻机理,并采用公式的形式拟合了含水率与最优通气量的关系.研究发现:含水率为80％的水田土壤减阻率可以高达21.9％,对...     

土壤消毒机蒸汽输送装置的设计与数值模拟

土传病虫害严重制约了设施栽培的发展。蒸汽消毒相比于其他土壤消毒方法,具有诸多优点,其利用高温杀死土壤中的病虫草害,提高了土壤的通透性和排水性,且对环境无任何污染。为此,基于脉冲式土壤蒸汽消毒机的总体结构,重点对蒸汽输送装置的注射针头以及蒸汽罩盖、针头间距、针头数目等蒸汽盘关键结构参数进行了设计。利用Fluent软件对土壤传热模型进行了数值模拟,分析了注射针头周围土壤的温度分布云图。结果表明:持续施加蒸汽7min、停止通蒸汽35min后,在半径10cm内、深度21cm范围内,土壤的温度能保持在90℃以上,验证了蒸汽输送装置结构的合理性。     

基于dsPIC30F5015的苗盘自动输送机构控制系统

针对目前移栽机中苗盘输送机构定位精度低、冲击大、调整不便、智能化程度低等问题,设计了一种基于ds PIC30F5015和Lab VIEW的苗盘自动输送机构控制系统。采用伺服电机作为动力源,并用光电编码器采集伺服电机转速,设计了以高性能微控制器ds PIC30F5015为核心的硬件系统。采用模块化程序设计思想,在MAPLAB IDE开发环境下,开发了下位机软件;采用Lab VIEW平台开发了上位机控制软件。在苗盘自动输送试验台上进行了位置控制性能试验,结果表明:苗盘定位误差小于0. 32mm,相对误差小于0. 5%。该系统运行稳定,响应速度快,控制精度高,能够满足苗盘自动输送和精确定位的实际需求。     

切-双纵流脱分装置试验研究与分析

阐述了切-双纵轴流脱粒分离装置的结构组成及工作原理,基于切-双纵流联合收获机,以喂入量、切流滚筒间隙及滚筒转速为影响因子,脱粒破碎率及脱粒损失率为指标,进行田间性能试验,并利用极差分析分别对破碎率、脱粒损失率单影响因子进行分析。结果表明:对脱粒破碎率影响的主次因素为BCA,即切流滚筒转速纵轴流滚筒转速喂入量,最佳组合为切流滚筒间隙25/30mm、滚筒转速907/1 043r/min、喂入量10.2 kg/s;对脱粒损失率影响的主次因素为BAC,即切流滚筒间隙喂入量滚筒转速,最佳组合为切流滚筒间隙25/30mm、喂入量10.2kg/s、滚筒转速953/1 096r/min。     

我国坡耕地农业机械化发展现状

随着经济的发展,用于农业用途的平耕地逐渐减少,为保证粮食出产总量,必须寻找未开发或开发程度低的耕地,坡耕地即为这种耕地。坡耕地分布在开阔地区,也有分布在丘陵山区,本文通过分析各个地区的农机使用情况,论述坡耕地农业机械化发展现状,旨在为发展坡耕地农机化提供参考。     

不同播期和灌水条件下冬小麦生物量变化与产量模拟

为了阐明播期和灌水对冬小麦生物量积累动态特征的影响并实现不同播期与灌水条件下的产量模拟,在吴桥实验站2年（2017—2019年）播期水分大田试验基础上,结合2011—2017年播期水分文献资料,采用“小麦钟”模型发育指数来定量模拟冬小麦的发育期,以Logistic模型定量模拟不同播期和水分处理对地上部生物量积累动态的影响,并建立冬小麦生物量模型,进而构建冬小麦产量模型。结果表明,播期通过影响冬小麦生长旺盛期来影响生物量积累;播期推迟,冬小麦生长旺盛期缩短而使生物量减小。不同水分处理造成的地上部最大生物量的差异主要由生物量的最大积累速率决定,生物量最大积累速率随灌水量的增大呈先增加后下降趋势。基于冬前积温和生长季供水量建立冬小麦生物量与产量模型,冬小麦地上部生物量实测值和模拟值的均方根误差（RMSE）和归一化均方根误差（NRMSE）分别为1980.2kg/hm2和15.7%,产量实测值和模拟值的RMSE和NRMSE分别为839.7kg/hm2和10.6%。基于发育指数的Logistic模型能较好地模拟冬小麦的生物量积累,对不同播期与灌水条件下的产量具有较好的预测效果。足墒播种条件下,冬小麦适宜冬前积温为200~600℃·d,生长季适宜供水量为200~450mm。该研究为华北地区合理调控播期灌水措施提供了科学依据,为不同播期与灌水条件下冬小麦产量预测提供了思路。     

一些重要作物拟茎点霉属病原生物学及致病机制研究概况

拟茎点霉属(Phomopsis)是腔孢纲球壳孢科真菌中的一个大属,含有100多个不同的种,可寄生于70多种不同科的植物。该属病原菌地域分布广泛,引起植物的叶枯、枝枯、烂茎、溃疡及果腐等严重病害,造成重大的经济损失。综述了一些主要作物的拟茎点霉属真菌病害在发生特点、致病症状及特性、生活周期循环、病害生化防控及病菌生物学特性等方面的研究进展,并展望了其今后研究热点及发展趋势,认为今后应加强从组织细胞学和分子生物学方面明确其致病机制,鉴定该属的致病特异性,并构建抗病分子育种技术体系等为病害安全、高效防控提供基因基础。     

储藏物冷却机在高温高湿区高大平房仓的应用

选用功率较小的储藏物冷却机与负压通风相结合,对福建漳州地区的粮面压盖稻谷仓进行降温冷却,通过改变粮面压盖方式实现冷却的均匀性和彻底性.累计运行时间112.7 h,降温3.3℃,水分变化为0.1％,达到了保水降温的效果.运行期间的降温单位能耗为0.47 kW·h/℃·t,符合《谷物冷却机低温储粮技术规程》的规定,结束降温后粮面压盖延缓了粮温复温.     

Cotton Chemical Topping by Applying DPC in Different Cotton-Growing Regions

[Objective] The objective of this study was to investigate the stability and universality of cotton chemical topping by applying mepiquat chloride (1,1-dimethyl-piperidinium chloride, DPC) in different cotton-growing regions. [Method] Field experiments were conducted in 2018 at 10 locations in the Yellow River basin (Hejian and Handan, Hebei province; Dezhou and Wudi, Shandong province), the Yangtze River basin (Dafeng, Jiangsu province; Huanggang, Hubei province), and Xinjiang area (Shihezi location I and loacation II, northern Xinjiang and Luntai and Shaya, southern Xinjiang). Local cultivars/lines were used, and the experiments were performed using a randomized complete block design with three or four replicates. Accompanied with typical DPC multi-application in each location, chemical topping was conducted at 10 days before manual topping (T1) or at the same time with manual topping (T2) by applying four dosages of DPC (0, 90, 180, 270 g·hm^－2), manual topping was used as the first control and non-topping as the second control. [Result] The time of chemical topping significantly affected cotton plant height (except for the results in Handan, Dezhou and Wudi) and the number of fruit branches (except for the results in Dafeng and Huanggang). It was observed that earlier chemical topping would result in lower cotton plant height and a fewer fruit branches. In Hejian and Shihezi location I, the average plant height across DPC chemical topping at T1 stage was not only lower than that of T2 stage but also 3.3 cm and 4.6 cm lower than that of manual topping, respectively. In most locations, chemical topping at T1 stage increased around two fruit branches per plant compared with manual topping, while in T2 stage the increased fruit branches per plant ranged from 2.3 to 7.7. Also, we found that a higher dosage of DPC resulted in shorter plant height (except for that in Huanggang). In some locations, plant heights of chemical topping with 180 g·hm^－2 or 270 g·hm^－2 DPC were even shorter than that of manual topping. The number of fruit branches per plant of 0 g·hm^－2 DPC increased by 2.4-8.3 compared with manual topping. However, chemical topping with 90-270 g·hm^－2 DPC significantly reduced the number of fruit branches compared with 0 g·hm^－2 DPC. There were no significant differences in the number of fruit branches among three DPC dosages (90, 180, and 270 g·hm^－2). In Handan, seed cotton yield of chemical topping at T2 stage was significantly lower than that of manual topping due to the decreased boll number, which is possibly associated with the high temperature and drought weather after chemical topping. While at other locations, most treatments of chemical topping by using DPC did not produce significant effects on yield. In addition, chemical topping by using DPC did not delay cotton maturity, characterized by their similar boll-opening rate and the first harvest rate to those of manual topping before spraying harvest aids. [Conclusion] Cotton chemical topping with DPC is more stable and universal across different cotton-growing regions. We suggest that 90-180 g·hm^－2 DPC could be used at the same time with manual topping for cotton chemical topping.     

农村居民点整理潜力与景观特征关系研究

为更好地研究农村居民点整理潜力与其景观特征之间的关系,以2012年临夏县土地利用数据为基础,测算南塬乡各行政村农村居民点整理的可实现潜力,并采用景观生态学方法分别计算各村居民点形状、规模和分布3个方向的景观指数,运用主成分分析各景观指数贡献率的基础上引入综合景观特征值,探讨了农村居民点类型尺度上农村居民点整理潜力与综合景观特征值之间的关系。研究表明：（1）农村居民点整理潜力受自然、社会、经济等因素影响,可实现潜力仅为理论潜力的一半;（2）受地形影响,南塬乡各村居民点斑块分布差异较大,综合景观特征值能够全面地反映出各景观指数对整体格局的影响;（3）综合景观特征值和可实现潜力有很强的相关性,综合景观特征值越高说明居民点斑块越规则,其整理潜力越小,例如江家寨村综合景观特征值最高为1.409,但其可实现潜力仅为2.23 hm²。