日光温室内太阳辐射估算模型的构建

日光温室内不同位置的太阳辐射量是作物光合和蒸腾模拟模型的重要参数,也是研究温室内墙体能量收支平衡方程的重要因子。该文研究了温室围护结构对太阳辐射的遮蔽,建立了可蔽视角的计算公式,在此基础上估算了晴天温室内任一位置的太阳直接辐射、散射辐射和太阳总辐射,并以辽沈Ⅱ型日光温室为例,将模拟结果与实测结果进行了比较,对造成模拟误差的可能原因进行了分析。研究结果表明:日光温室内模拟的散射辐射和总辐射的日变化与实测值趋势较为一致,模拟值要略高于实测值,平均偏高6.4%和8.8%,误差的可能来源有大气透明系数、棚膜透光率的估算误差、承重骨架的遮蔽及人为观测的误差。研究结果可为日光温室内不同位置作物光合蒸腾模拟、群体光分布模拟、围护结构能量平衡等模拟模型提供参考。     

日光温室太阳辐射模型构建及应用

太阳辐射是影响日光温室光、热环境的重要参数,准确获得温室内部墙体与地面的太阳辐射照度变化规律可对温室设计建造、温室内环境调控与作物生产起到重要的指导意义。该文在总结已有日光温室太阳辐射模型的基础上,通过气象数据,地球、太阳的运动规律以及太阳光线与日光温室前屋面入射角的关系,建立了较为完善的日光温室太阳辐射模型,并利用该模型对温室内部辐射规律进行分析。采用典型晴天数据对模型进行检验,结果显示计算值与实测值平均偏差最大为63.46 W/m~2,平均绝对误差最大为63.48 W/m~2,均方根误差最大为79.18 W/m~2,决定系数在0.95～0.99范围内。利用该模型分析温室内部辐射规律发现,相比不同位置屋面角度的影响而言,透光率受时间即太阳方位与太阳高度角的影响更大。温室墙体表面与地面太阳辐射照度随季节不断变化,春秋分是一年中墙体与地面接受太阳辐射时间最长的节气,该日墙体表面与地面太阳辐射照度大致相当。春分到秋分期间,地面辐射照度高于墙体表面;从秋分到春分期间,墙体表面太阳辐射照度大于地面。不同区域温室内太阳辐射日积累量主要受纬度影响,低纬度地区较高纬度地区而言,冬季太阳辐射日积累量大,夏季太阳辐射日积累量小。研究结果可为日光温室内墙体蓄热、屋面优化、作物种植、围护结构能量平衡等研究提供理论参考与相关数据。     

基于GA的果树仿形喷雾神经网络混合模型研究

基于BP神经网络研究果树施药仿形喷雾参数之间的关系发现,BP神经网络无法避免不稳定性和局部极小的局限性,为此,该文利用遗传算法优化BP神经网络的权系数,构建遗传算法和BP的果树仿形喷雾神经网络混合模型。研究结果表明：混合模型的计算精度比BP模型要高,其平均相对误差由0.05减为0.019,均方误差由0.005减为0.002。在预测应用中,不仅绝对误差减少,而且合格率从原来的60%提高到80%,较好地解决了单纯神经网络模型的不稳定性,避免局部极小的缺点。     

果树施药仿形喷雾神经网络模型及其应用

在试验的基础上,建立了反映果树施药仿形喷雾过程参量与分布质量系数之间映射关系的BP神经网络模型,在建模中运用了正交试验设计、交叉评价网络训练法、样本标准化处理和主元分析等技术,对网络结构及其参数进行了优选。结果显示,网络模型输出同试验结果相关系数R达到0.99,表明具有广泛的适应性。同时,该网络可以实现各种定量分析计算,例如：预测在特定过程参量下的分布质量系数,或者根据指定的效果目标,确定合适的喷雾参量等。     

Plant water relations in lychee: Effects of solar radiation interception on leaf conductance and leaf water potential

The effect of radiation interception on leaf conductance and leaf water potential in six-years old lychee trees (Litchi chinensis Sonn. cv. Bengal) was investigated during the dry season in subtropical Queensland, Australia. A high degree of exposure of leaves to direct radiation raised leaf-air water vapour concentration gradient (Δw) and resulted in lower leaf conductance and leaf water potential. Interior leaves of the south side of trees were less sensitive to atmospheric and radiation effects and are the best indicator of drought stress in lychee. Completely random or stratified sampling is necessary to estimate a true mean value for calculation of canopy transpiration or photosynthesis.     

用于振动采收的有果有叶果树振动模型构建

现有的果树振动有限元模型仅对果树的枝杆部分进行重建,忽略了果树的果实与树叶对果树固有频率的影响。该研究提出了一种将激光扫描技术与有限元法相结合,用空间6自由度梁单元构建果树空间振动模型。基于研究果实和树叶在树枝上的位置和质量分布规律,构建果树有果有叶、无果有叶、无果无叶振动模型。并对一棵小型实体银杏树分别处于有果有叶、无果有叶和无果无叶3种状态的频谱特性进行测试,并与构建的理论振动模型计算的各阶固有频率进行比对分析。结果表明,计算固有频率数量要多于实测所体现出来的固有频率数量,但实测固有频率均可在仿真频率中找到十分相近的值,且仿真模型的果树各枝振型幅值与实测的各枝加速度响应幅值相互的对应关系基本吻合;计算模型的最大相对误差为5.76%。该研究所述建模方法能够较准确有效地获取果树固有频率。     

Winter chilling trends for deciduous fruit trees in Australia

Deciduous fruit trees require exposure to cold winter temperatures to fulfil chilling requirements allowing production of normal harvests. Trends in chill accumulation over the last 100 years were investigated at a number of important horticultural locations in Australia. Historical analysis is a necessary first step when considering potential impacts of climate change. Chill was examined using four chill models; the 0-7.2 °C, Modified Utah, Positive Utah and Dynamic models. Differences between locations were found with notable recent declines at Orange, Lenswood, Tatura, Yarra Valley and Bacchus Marsh. Other locations have remained stable with no location exhibiting a consensus increase in chill across all models. Trends in chill were shown to differ between models with results indicating that the 0-7.2 °C model frequently behaved differently to the other three chill models. These results highlight the need for multi-model analysis for chill trends, especially in a climate change context, to avoid maladaptation.     

果树施药仿形喷雾的位置控制系统

按照仿形喷雾的原理，研制了一种以单片机为核心的非接触式仿形喷雾位置控制系统，即采用超声波位置传感器检测果树的位置和实际形状，由系统控制步进电机带动喷头组运动，使喷头在理想的喷雾距离下工作。为了适应喷雾对象和环境的不确定性，设计了自适应模糊控制程序，带动喷头的步进电机则采用数字脉宽调制方式(DPWM)控制。试验结果表明，该控制系统满足仿形喷雾的技术要求。     

Radiocesium transfer into the fruit of deciduous fruit trees contaminated during dormancy

Following the accident at the Tokyo Electric Power Company, Fukushima Daiichi Nuclear Power Plant (FDNPP), radiocesium (¹³⁴Cs + ¹³⁷Cs) concentrations in deciduous mature fruits were determined in orchards in the northern area of Fukushima Prefecture. At the time of the nuclear accident, most deciduous fruit trees were in the dormant stage prior to bud burst. To evaluate the relationship between radiocesium deposition in the soil and fruit contamination, radiocesium concentrations were measured from the 5-cm topsoil and from six fruit species across 17 orchards in 2011. The vertical distribution of radiocesium in the topsoil (0–30 cm in depth) and its spatial distribution in the 5-cm topsoil underlying the tree canopy of a peach, Prunus persica (L.) Batsh, orchard (“Akatsuki” cultivar) were also investigated. Significant correlations between the radiocesium concentration in the mature fruit and that in the 5-cm topsoil layer were observed for the 17 orchards as well as for the trees of the peach orchard. However, 93% of the ¹³⁷Cs found in the 30-cm soil core was retained within the top 3 cm of the soil in the peach orchard. Considering the profile of the root of this deciduous fruit tree, we assumed a negligible level of radiocesium uptake via the roots. However, the possibility of inward migration via the bark was undeniable, because some radiocesium adhered to the tree canopy before bud burst while depositing on the soil surface. Additionally, transfer factors for peach and grape, hybrid of Vitis labrusca L. and Vitis vinifera L., from young, uncontaminated trees cultivated with contaminated soil were lower than those previously reported.     

半日光间歇弥雾果树育苗系统及其应用

为解决某些果树树种繁育困难的问题,研制了半日光间歇弥雾果树育苗系统,用于甜樱桃矮化砧木吉塞拉6号嫩梢扦插育苗。通过对育苗环境主要因子的宽范围高精度调控,45 d育成新苗,生根率93.66%以上,每株平均生根7.29条,新苗移栽成活率95%以上。与传统扦插育苗和组培繁育相比,育苗周期和成本均显著降低。     

Crop productivity in relation to interception of photosynthetically active radiation

The attenuation of photosynthetic photon flux density (PPFD) in maize, sorghum, pigeonpea, and a maize/pigeonpea intercrop in the operational research watersheds at ICRISAT Center in India was measured on a weekly basis throughout the growing season. A 2-m high frame covering an area of 3 m² was designed to accommodate four manually-operated traversing quantum sensors for the measurement of PPFD. The interception of PPFD by the crop canopies was found to be closely related to the leaf area index. The plots of the regression relationship between dry matter for different crops and cumulative intercepted PPFD (grams of dry matter/einstein intercepted) were used to define the efficiency of light interception by crops. The maize/pigeonpea intercrop proved to be most efficient, followed by maize, sorghum, and pigeonpea. The Bouguer—Lambert Law was used to compute the extinction coefficient of PPFD of plant canopies. The interception of PPFD could be accurately predicted for sorghum and maize using this law, but in the case of pigeonpea the law was not satisfactory for accurate prediction of PPFD interception.     

果树仿形喷雾的虚拟研究

鉴于很多研究者只通过试验来定性地研究各种过程参量对喷雾质量的影响,为此作者基于已有的实际试验数据,提出了从理论上对喷雾进行虚拟研究,构建三维空间中的喷雾数学模型,实现了虚拟系统,并对虚拟的结果与实际数据进行分析和对比。结果表明,喷雾过程是一个非常复杂而且难以描述的过程。模型能虚拟实际中雾滴在果树中的飞行情况,能够反映实际喷雾的关键元素,可以仿真喷雾沉积分布的趋势。虚拟喷雾模型中设置不同的喷嘴高度,得到的沉积率的趋势一样,说明喷雾高度的变化对结果没有太大的影响。喷雾模型可对开发果树仿形喷雾预测系统或产品提供一定的理论支持。     

AWRA-L模型估算区域林冠降雨截留量

目前模拟林冠截留的Gash模型的应用多是针对某一特定点或特定林分开展,而在区域范围内的应用国内尚无报道,在国外也仅见其在澳大利亚水资源评价系统AWRA.L模型中的应用。该研究介绍了AWRA-L(Australian water resources assessment-landscape)模型,并利用GI_。ASS LAI遥感数据结合浸水法获得的林冠持水量,使用该模型对试验点白桦(Betula platyphylla Suk.)天然次生林2013年的林冠截留进行模拟。结果显示,基于Van等改进过的Gash模型的AWRA.L模型和基于Gash(1979)模型的AWRA—L(1979)模型,对累积林冠截留模拟的绝对误差分别为-4.4和1.5 mm,相对误差分别为-8.7%和3.0%;对于单场降雨林冠截留的模拟结果显示,2模型的模拟误差值分别为(-0.15±1.64)和(-0.03±1.39)mm,模拟值与实测值之间无显著差异。研究结果说明结合GLASS LAI遥感数据,AWRA-L模型可以应用于区域范围林冠截留的模拟,模拟结果较好。     

基于器官尺度虚拟玉米冠层直射光分布的快速计算模型

为了给精确农业研究中所需的植物冠层光分布快速计算提供解决方法,提出了一个基于虚拟相机的玉米冠层直射辐射分布快速计算模型。该模型主要包括一个能代表田间玉米植株群体空间结构特征的虚拟冠层和一个虚拟相机,采用虚拟相机从太阳入射方向拍摄冠层图像,通过图像判读计算出植株各器官的太阳直射辐射分布。从模拟精度与模拟时间两方面评估了该模型的有效性。结果表明,该模型能很好地模拟器官尺度的植株光分布,并且比现有模型明显地缩短了计算时间。在引入计算虚拟冠层最小复制植株数的算法后,该模型的计算时间还能进一步缩短。另外,还探讨了虚拟冠层的植株器官形态简化描述的可行性,结果表明过度简化会导致模拟误差的明显增加。     

山区太阳直接辐射的空间高分辨率分布模型

该文以山区的高空间分辨率DEM数据为主要数据源,从中分别提取经度、纬度、坡度、坡向等相应的地形要素栅格数据,再结合多年平均的实际日照百分率资料,利用GIS技术建立山区实际太阳直接辐射的高空间分辨率分布模型,实现太阳直接辐射空间分布规律的可视化表达,分析了山区各月太阳直接辐射的空间分布特征,对于山区的农业、林业和生态环境等方面的研究具有重要的指导意义。     

调亏灌溉在果树上应用的研究进展

我国果树具有栽培面积大、经济效益高等特点,但其耗水量较大,同时我国又是水资源缺乏的国家,在果树上实行节水灌溉势在必行.本文综述了调亏灌溉的定义、发展及其在果树上的应用和对果树产量、品质等的影响,探讨了调亏灌溉研究中存在的问题,并提出展望.     

Using analogies from soil science for estimating solar radiation

Using analogies from soil science a new global radiation estimation method was developed and tested on a large North-American meteorological database. The newly developed procedure was compared to the well-known, Donatelli-Campbell method. Both the overall indicators and the more detailed analysis of the model performance confirmed that the new method is more efficient than the Donatelli-Campbell method. The improved performance is due to the greater number of parameters, as well as to the more adequate function type it uses during the calculation. Results suggest that it is sufficient to have 2 year-long data series for parameterizing the new method to provide at least as accurate radiation estimates as provided by the Donatelli-Campbell method. The new method can be efficiently used for locations with no radiation measurement by combining it with a simple spatial interpolation technique.     

The response of fruit trees in Michigan to trickle irrigation

Abstract

Trickle irrigation was evaluated in 2 seasons on sour cherry, plum, peach, and apple. Rates of water applied were 0, 1.9, 3.8, and 7.6 liters per hour (LPH) in 1975, and 0, 3.8, 7.6, and 15.2 LPH in 1976. Peach yields were increased both years. Apple yields were increased in 1976. Leaf content of Na, Ca, Mg, Mn, and Al in sour cherry; P, Cu, B, and Al in peach; and P, Na, Fe, Cu, and Al in plum was increased by irrigation.     

数字果树及其技术体系研究进展

果树是重要的农林植物.在万物智联时代,利用数字化、智能化、网络化技术建立数字果树技术体系,实现对果树生命、生产和生态复杂系统的高效感知、认知和智慧管控,对于果业实现数字化转型具有重要意义.该研究在数字植物技术范畴下,系统论述了数字果树的概念和内涵,提出了数字果树技术体系框架.重点在果树表型信息获取、环境数据获取、三维模...