杨梅简易气调保鲜过程中气体成分变化及保鲜效果     

戚行江  郑锡良  梁森苗  柴雪芹  周利秋  李伯钧 《果树学报》2005,22(5):496-499

以东魁杨梅为试材,研究简易自发气调贮藏(MA)和充氮气调贮藏(NA)条件下,杨梅贮藏小环境中气体成分的变化和对贮藏效果的影响。结果表明:在MA中,乙烯浓度在2d达到高峰;O2前4d浓度急剧下降,后维持在2.48%至1.78%;CO2一直呈上升趋势,试验过程浓度提高了124.3%。在NA中,乙烯高峰出现时间明显推迟、峰高降低;O2浓度维持在2.28%-1.82%,CO2变化与MA相似,浓度提高了131.3%。MA和NA均有效延缓杨梅鲜果的软化变质,减缓果实硬度和总糖的下降速率。贮藏至16d,NA和MA中果实变质率分别比对照下降31.6%和22.5%,硬度比对照增加25.93%和21.98%,总糖含量处理与对照无明显差异。  相似文献   

Impact on soil physical properties of using large-grain legumes for catch crop cultivation under different tillage conditions     

《European Journal of Agronomy》2016

In Central Europe, various plant species including large-grain legumes and their mixtures are grown as catch crops, particularly between grains harvested early and subsequent summer crops. This article investigates the question of how soil structure in the topsoil is influenced when catch cropping with large-grain legumes (experimental factor A: without catch crop, with catch crop) under different ploughless tillage conditions during catch crop seeding (experimental factor B: deep tillage/25–30 cm, shallow tillage/8–10 cm). Five one-year trials were performed using standard machinery at various sites in Germany. Soil core samples extracted from the topsoil in the spring after catch crop cultivation served to identify air capacity, saturated hydraulic conductivity and precompression stress. The above-ground and below-ground biomass yields of the catch crops were also determined at most of the sites. In addition, the soil compaction risk for the working steps in the experiments was calculated using the REPRO model.The dry matter yield of the catch crops varied considerably between the individual trial sites and years. In particular, high levels of dry matter were able to form in the case of early seeding and a sufficient supply of precipitation. The soil structure was only rarely affected positively by catch crop cultivation, and catch crops did not contribute in the short term to loosening already compacted topsoils. In contrast, mechanical soil stresses caused by driving over the ground and additional working steps used in cultivating catch crops often led to lower air capacity in these treatments. This is consistent with the soil compaction risks calculated using the REPRO model, which were higher in the treatments with catch cropping. Catch crop cultivation also only resulted in improved mechanical stability at one location. The positive effect of deep ploughless tillage on air capacity and saturated hydraulic conductivity, however, became more clearly evident regardless of catch crop cultivation. In order for catch crop cultivation with large-grain legumes to be able to have a favourable impact on soil structure, it is therefore important that cultivating them does not result in any new soil compaction. In the conditions evaluated, deep tillage was more effective at loosening compacted topsoil than growing catch crops.  相似文献   

Efficient reduction of biomass,seed and season long pollen production of common ragweed (Ambrosia artemisiifolia L.)     

《Urban Forestry & Urban Greening》2017

Ragweed (Ambrosia artemisiifolia L.) is a noxious plant that not only is a troublesome agronomic weed that causes economic damage to agricultural crops but also − and even more importantly − causes severe health problems due to its severe allergenicity. The pollen of invasive ragweed has become a major allergenic risk factor in urban areas in newly occupied regions. Many urban areas prohibit herbicide application; thus, mowing is the most widely used control measure. Counting pollen is labour intensive; therefore, pollen production data are mainly based on estimations. Field experiments were conducted to determine the effects of different mowing scenarios, plant density and cutting height on the biomass, pollen production and seed production of common ragweed plants. Ragweed plants were mown twice: just before the flowering of terminal racemes (BBCH 59) and when the flowers of the re-sprouting lateral shoots reached BBCH 59. A 1- to 3-cm cutting height produced the greatest pollen reduction compared to that of intact control plants (94%) based on a season-long pollen collection. The number of female flowers also significantly decreased (97%). Compared to the control, the onset of pollen discharge was delayed by 5 weeks and the length of the pollen discharge period decreased from 9 to 4 weeks. The season-long unique and reproducible pollen production data can be integrated with airborne pollen modelling and population management strategies.  相似文献   

CNG发动机燃烧室形状对气流运动和燃烧特性的影响     

江冰  武昭晖  何云堂 《农业机械学报》2015,46(1):338-344

为提高天然气发动机的燃烧品质,基于6105型涡轮增压CNG发动机,通过建模分析法,对发动机不同燃烧室形状对缸内气流运动和燃烧特性的影响进行了三维数值模拟研究。研究结果表明,燃烧室形状对挤流的形成和燃烧过程有着重要影响。缩口型燃烧室具有较大的挤流强度和较长的涡流持续期,火焰传播速度快,燃烧性能好,但其火花塞附近的热负荷较大,NOx的含量高。敞口型燃烧室挤流强度较弱,火焰传播速度较慢,燃烧性能最差。直口型燃烧室则介于两者之间,既能保证较快的火焰传播速度和较好的燃烧性能,又降低了其火花塞附近的热负荷和NOx的排放量,是较适合天然气发动机采用的燃烧室。  相似文献   

基于SHAW模型的冬小麦近地面层气温模拟     

刘峻明  汪念  王鹏新  胡新  黄健熙 《农业机械学报》2015,46(S1):274-282

利用一维多层水热耦合SHAW（The simultaneous heat and water）模型,在田间实验的基础上,模拟河南省商丘地区2015年冬小麦拔节后近地面层0~40 cm垂直方向上的每小时气温变化特征。结果表明,冬小麦近地面层气温模拟整体效果较好,其中48%模拟的绝对误差低于1℃,75%模拟的绝对误差低于2℃,不同高度上模型效率ME均大于0.94;夜晚气温的模拟效果优于白天的模拟效果,白天11:00—14:00气温被过低估计,并随着近地面层高度的增加,模拟值误差越大;近地面层内3种气温特征值模拟效果的优劣依次为：日平均气温、日最低气温、日最高气温,其中,日平均气温模拟值与实测值基本吻合,日最低气温被略微高估,日最高气温被过低估计。此外,SHAW模型在冬小麦拔节后6个生育期的模拟效果均存在差异,拔节期、灌浆期和乳熟期模拟效果较好,孕穗期和开花期次之,抽穗期模拟效果相对较差。  相似文献   

基于冠层温度和土壤墒情的实时监测与灌溉决策系统   总被引：4，自引：0，他引：4  

蔡甲冰  许迪  司南  魏征 《农业机械学报》2015,46(12):133-139

设计了一个可以在线连续监测田间作物冠层温度、环境信息和土壤墒情的实时灌溉决策系统,并将其安装于农田进行了1 a实际运行和观测。系统采用太阳能供电和微处理器进行数据采集和管理,为野外的实际应用提供了保障。系统配置了红外温度、空气温/湿度、土壤水分/水势等传感器,能够及时采集田间全面的同步数据,排除了异地观测所形成的数据误差。采用悬臂式多点采集下垫面红外温度检测方法,可以快速采集更多和更高精度的数据,避免单点测量的人为误差。系统配备的快速锁紧装置,能够根据下垫面作物的生长情况进行传感器位置高度调节,使检测数据更符合田间实际情况。通过运行管理和监测数据分析可见,所监测数据能够很精细的刻画田间作物实际生长状况,可以用于灌区综合灌溉决策,实现田间精量灌溉管理和控制,为灌溉管理的精量化和智能化提供数据支持。  相似文献   

静压式平面空气轴承压力场的有限元分析   总被引：1，自引：0，他引：1  

马明建  辛世界 《农业机械学报》1994,25(4):91-97

采用有限元理论分析了静压式平面空气轴承的压力场，并讨论了空气轴承压力场边界条件的处理。分析结果表明，空气轴承的压力场呈现尖峰状分布。分析结果已应用于三坐标测量机的空气轴承设计中，取得了令人满意的效果。  相似文献   

奔驰W220型空气悬架系统分析     

刘跃明  林志丰 《拖拉机与农用运输车》2010,37(5)

对奔驰W 220型空气悬架系统的结构、功能、工作原理进行分析,阐述了该悬架通过电脑接受传感器的信号并经处理后,由电脑控制执行机构以实现对气体、液体的控制,从而改变悬架刚度和阻尼,以满足车辆在不同道路状况下行驶对舒适性、操控性和通过性的要求。  相似文献   

畜果结合生态养殖模式的研究     

赵芙蓉  王占彬  李保明  王朝元  梁臣 《家畜生态》2006,(4)

本研究系统探讨了果园和畜禽养殖的种养结合型生态模式,分析研究了“猪-沼-果”、“草-鸡-果”两种生态模式下的猪、鸡生产性能,畜舍空气质量以及苹果的产量和质量。研究结果表明:生态养殖模式下生长肥育猪和鸡的增重显著高于庭院养殖(P<0.05),分别提高了17.46%和29.28%;猪舍、鸡舍空气中的CO2和NH3比庭院猪舍、鸡舍显著降低(P<0.05);苹果产量比单纯果园平均分别提高28.97%和21.15%,含糖量分别相对提高6.79%和6.36%。  相似文献   

Enhancement of photosynthesis and growth of tomato seedlings by forced ventilation within the canopy   总被引：1，自引：0，他引：1  

Toshio Shibuya  Johshin TsuruyamaYoshiaki Kitaya  Makoto Kiyota 《Scientia Horticulturae》2006

A forced ventilation system that directs airflow upward or downward within a canopy was developed for plant culture in order to enhance photosynthesis and growth of the plant canopy. Tomato seedling canopies including the seedlings, growing medium, and a plastic tray were used for the experiments. In the upward and downward ventilation systems, air flows upward and downward, respectively, within the plant canopy; this is achieved by blowing and drawing air from holes (Ø 6 mm) made in plastic pipes positioned on the surface of the growing medium. A horizontal airflow system was used as a conventional system to compare the performance of the experimental ventilation systems. Using the upward and downward ventilation systems, the effects of air directions and air velocities on the CO₂ exchange rate of the tomato seedling canopy and the growth of the seedlings were compared with those observed using the conventional horizontal airflow system. The forced ventilation within the plant canopy enhanced the CO₂ exchange rate of the canopy and the dry masses of the seedlings by 1.4–1.5 and 1.2–1.3 times, respectively, as compared to the conventional horizontal airflow. When the leaf area index (LAI) increased from 1.2 to 2.4, there was only a 5% decrease in the CO₂ exchange rate per unit leaf area in the downward ventilation system, whereas there was a 20% decrease in the CO₂ exchange rate per leaf area in the horizontal airflow system. The coefficient of variation for the dry mass of the seedlings was higher in the downward system than in the other systems. These results demonstrate that forced ventilation within the canopy is an effective technique to enhance the gas exchange of the plant canopy and the consequent plant growth.  相似文献