基于温差电池的温室地埋供热金属管道阴极保护改进

北方温室为种植反季节植物以及南方植物,普遍采用地埋供热金属管道供热。阴极保护技术可以有效控制土壤对管道的电化学腐蚀,但常规的外接电流阴极保护方式成本高、占地大,牺牲阳极方式的保护寿命过短。为了给温室地埋供热金属管道提供可靠的阴极保护,该文利用地埋供热金属管道表面余热,基于温差电池,对地埋供热金属管道提供外接电流方式的阴极保护。通过现场试验发现,该装置温差电池正常工作时冷热两端温差为33.2℃,当该装置提供的保护电位为–1 100 m V时,管道保护度达到了92.79%。该研究为温室地埋供热金属管道的保护提供了一种较为可行的方案,同时也对外接电流方式的短距离管道保护技术进行了初步探索。     

连栋温室地中热交换系统贮热加温的试验

为解决连栋温室冬季能耗大、费用高的问题,进行了采用地中热交换系统部分代替燃煤的贮热加温试验。测定了空气和管道周围土壤贮、放热前后的温度等参数变化,系统在夜间加温能力可达加温热流量６０Ｗ／ｍ^２,可有效保证夜间室内气温高于室外１１℃以上。     

长江中下游地区Venlo型温室空气温湿度以及黄瓜蒸腾速率模拟研究

根据温室能量和质量平衡的物理学原理,建立了一个以温室外气候条件(太阳辐射、温度、湿度、风速等)为驱动变量,以温室结构、温室覆盖材料、温室内作物(高度、叶面积指数)为参数的温室小气候模拟模型,并利用上海Venlo型温室的三季试验数据对模型进行了检验。结果表明：模型能较好地预测中国长江中下游地区Venlo型温室内夏季和冬季空气温度、湿度以及作物蒸腾速率。模型对该地区夏干季节(2001年8月,三伏天)、夏湿季节(2002年6月下旬至7月中旬,梅雨季节)和冬季(2002年1月27日~2月5日)温室内空气温度、湿度以及作物蒸腾速率预测值与实际观测值的决定系数(R²)和标准误(SE)分别为：0.89,0.75,0.52;1.1℃,4.4%,0.040 g·m^-2·s^-1;0.80,0.84,0.77;1.5℃,4.4%,0.018 g·m^-2·s^-1;0.84,0.59,0.73;1.6℃,6.0%,0.012 g·m^-2·s^-1。该研究为进一步探讨温室环境的优化调控提供了理论依据和决策支持。     

空间电场对植物吸收CO2和生长速度的影响

为研究空间电场对植物吸收CO₂和生长速度的影响，首先采用同位素示踪法，分析了不同空间电场调控营养液栽培的番茄秧吸收CO₂气体和HCO^-₃阴离子的能力，证实了 ¹⁴C—HCO^-₃是一种受控于空间电场变化的阴离子，且空间电场强度的变化方向调控着 ¹⁴C—HCO^-₃阴离子流的流动方向。在此基础上以蕹菜(空心菜)为试验材料，采取空间电场与增施CO₂浓度的参数组合，做对比生长试验，通过红外线CO₂分析法揭示了空间电场的极性对植物吸收CO₂的速度有显著影响，且正向空间电场能显著促进植物对CO₂的吸收，并得到正向空间电场与足量的CO₂浓度相配合能大幅度提高温室蔬菜生长速度，使作物产量倍增的结论，为建立空间电场促进植物生长技术提供理论依据。     

铜对伴矿景天生长及锌镉吸收性的影响

利用植物生长室水培试验和温室土培盆栽试验相结合,研究了Cu对Zn、Cd超积累植物伴矿景天生长及Zn、Cd吸收性的影响。水培试验结果显示,0.31～50μmol/L Cu处理14天对伴矿景天生长及对Zn、Cd吸收性没有显著影响;但100μmol/L Cu处理显著抑制植物生长,降低地上部Zn、Cd及根中Cd浓度,对根中Zn浓度变化没有显著影响。盆栽试验结果发现,在土壤Cu仅为3.61 mg/kg时伴矿景天生长不良,外加Cu显著促进其生长并随Cu浓度升高效应增加;但施用3 mmol/kgEDDS和再次外加250 mg/kg Cu处理使伴矿景天因体内Cu积累量过高而导致明显毒害,地上部Cu最高达1 068 mg/kg。可见低量Cu处理可促进伴矿景天生长,利于植物对土壤Zn、Cd的吸取修复,但土壤中Cu浓度过高将抑制Zn、Cd超积累植物的生长,降低其Zn、Cd吸收能力,在利用该Zn、Cd超积累植物修复高Cu的Zn和Cd污染土壤时应采取适当措施降低Cu毒害效应。     

塔里木沙漠腹地日光温室温度效益

塔克拉玛干沙漠腹地日光温室在冬季未加热时,温室内气温比室外高14℃,地温高15℃以上,可确保抗寒力较强的蔬菜正常生产;苇草草帘增温0.9℃,中棚增温3.7℃;当与温室被、中棚联合使用时,可确保绝大部分蔬菜正常生产。加热可使内外温差达30℃,可提供如西红柿、黄瓜、辣椒等对温度要求较高的蔬菜品种获得高产所需的最佳温度环境。沙漠地区直射光可使温室内温度迅速上升达3.5℃/h,散射光也可确保温度不迅速下降。通风效率：温度上升减慢为0.33℃/h·m²～2.44℃/h·m²,温度下降增快3.7℃/h·m²。温室内温度不均,其规律为两端高、中间低;北面高、南面低。加热炉间距离应在25m左右,以使温室内温度分布更均匀。     

温室黄瓜干物质分配与产量预测模拟模型初步研究

依据温室黄瓜(Cucumis sativus)器官生长与温度和辐射的关系,建立了基于分配指数和采收指数的温室黄瓜干物质分配与产量预测模拟模型,并利用不同品种和基质的试验资料对模型进行了检验。结果表明,模型对黄瓜地上部分干重、根干重、茎干重、叶干重、果实干重的预测结果与1∶1直线之间的R²分别为0.98,0.73,0.83,0.92,0.94;RMSE分别为232,6.8,157.6,173.9,196.8 kg/hm²。模型对黄瓜产量的预测结果与1∶1直线之间的R²为0.80,RMSE为7526.4 kg/hm²。本模型对不同基质、品种的黄瓜干物质分配和产量的预测值与实测值符合度均较高,说明本模型的普适性较好。模型不仅能较好地预测中国现有生产水平下温室黄瓜的干物质分配及产量,而且可以为实现中国温室黄瓜生产环境优化调控和模式化栽培管理提供决策支持。     

紫茎泽兰和黄顶菊入侵对土壤微生物群落结构和旱稻生长的影响

为比较入侵植物与本地植物对土壤微生态影响的差异, 探索外来植物入侵的土壤微生物学机制, 本研究通过同质园试验, 比较分析了2种入侵菊科植物(紫茎泽兰、黄顶菊)和2种本地植物(马唐、猪毛菜)对土壤肥力和微生物群落的影响, 并通过盆栽反馈试验验证入侵植物改变后的土壤微生物对本地植物旱稻生长的反馈作用。同质园试验结果表明: 2种入侵植物和2种本地植物分别对土壤微生态产生了不同的影响, 尤其是紫茎泽兰显著提高了土壤有效氮、有效磷和有效钾含量,紫茎泽兰根际土壤中有效氮含量为39.80 mg·kg^-1,有效磷含量为48.52 mg·kg^-1。磷脂脂肪酸指纹图谱结果表明, 2种入侵植物与2种本地植物相比, 较显著增加了土壤中放线菌数量, 而紫茎泽兰比其他3种植物显著增加了细菌和真菌数量。盆栽结果表明: 黄顶菊生长过的土壤灭菌后比灭菌前旱稻株高增加113%, 紫茎泽兰也使旱稻的株高增加17%。由以上结果可知, 紫茎泽兰和黄顶菊可能通过改变入侵地土壤的微环境, 形成利于其自身生长扩散的微生态环境从而实现其成功入侵。     

基于鱼类保护目标的椒江环境流量研究

以鱼类为保护目标, 通过建立概念模型将鱼类保护目标与流量之间的关系相联系, 识别了与椒江鱼类保护目标相关的环境流量组成要素。采用FLOWS 方法, 计算了椒江2 个断面的环境流量, 柏枝岙断面的低流量为6.8~17.3 m³·s^-1、高流量为22.2 m³·s^-1, 低流量脉冲为74 m³·s^-1, 高流量脉冲为110 m³·s^-1, 齐岸流量为948 m³·s^-1; 灵海断面的低流量为16.0~31.8 m³·s^-1, 高流量为46.0 m³·s^-1, 齐岸流量为2 488~3 184 m³·s^-1。并得出每组环境流量出现时间、持续时间和出现频率等的推荐结果。与Tennant 方法的计算结果比较, 采用FLOWS 计算方法能够反映环境流量的季节性变化特点, 同时体现了环境流量与自然流量过程的一致性。此研究结果可为椒江的水资源合理利用与河流生态系统保护提供理论依据。     

不同改良剂对镉污染土壤中小白菜吸收镉的影响

采用盆栽试验, 研究了施用石灰、钙镁磷肥、泥炭、碱渣4种土壤改良剂对外加镉污染的赤红壤上小白菜产量、镉吸收量、土壤有效态镉及pH的影响。结果表明: 外加1 mg·kg^-1和5 mg·kg^-1镉对小白菜生物量无显著影响, 且1 mg·kg^-1镉对小白菜生长有一定的促进作用; 施用改良剂对镉污染土壤上小白菜无显著增产效果。施用4种改良剂均能降低小白菜地上部镉含量, 作用效果为石灰≈泥炭>碱渣>钙镁磷肥。不同改良剂对小白菜根部镉含量影响不同, 泥炭和石灰在所有镉浓度下、钙镁磷肥在0和1 mg·kg^-1镉浓度下可显著降低根部镉含量, 而碱渣无明显作用, 种植两茬规律一致。土壤有效态镉含量与pH呈显著负相关; 施用石灰、碱渣、钙镁磷肥使土壤pH显著升高, 有效态镉含量显著降低, 从而降低小白菜对镉的吸收; 泥炭可显著提高土壤pH, 虽降低土壤有效态镉作用效果不显著, 但显著降低小白菜体内镉含量, 这可能与土壤中形成难以被植物吸收的镉有机结合物有关。两茬蔬菜种植结果显示, 施用后期改良剂对镉污染的抑制效果也较明显。     

型钢拱架日光温室结构稳定性能及参数分析

型钢拱架日光温室结构的主要受力构件长细比大,暴雪等极端灾害天气下易引发结构失稳灾变。针对此问题,该研究利用弹塑性力学理论和非线性有限单元法,建立型钢拱架日光温室结构精细化有限元模型,开展雪荷载下日光温室稳定性能分析;通过对型钢截面类型（平椭圆形截面、箱形截面和几字形截面）、温室跨度（8、10和12 m）、雪荷载分布形态（分布厚度不均匀和分布区域不对称）等参数下进行日光温室失稳全过程分析,分别确定日光温室稳定承载力,揭示雪荷载分布对日光温室稳定承载力的量化影响;结合日光温室的荷载系数-位移全过程曲线和不同加载时刻点的变形图、应力图、轴力图与弯矩图,从直观现象和内在本质两个层面深入探明日光温室的静力失稳机理。分析结果表明：在保证不发生平面外整体失稳的前提下,当型钢截面面积和翼缘宽度相同时,相较于箱形截面型钢、几字形截面型钢,采用平椭圆形截面型钢拱架的日光温室稳定承载力分别提高了19.2%和44.2%;跨度对日光温室稳定承载力的影响较大,与8 m跨度相比,10、12 m跨度的日光温室的荷载系数分别下降了27.1%和57.9%;相较于均匀分布雪荷载,在非均匀分布雪荷载下日光温室的稳定承载力最大下降63.8%;相较于不设置拉杆和撑杆的情况,单独设置拉杆的日光温室稳定承载力最大可提高9.0%,单独设置撑杆的日光温室稳定承载力最大可提高66.8%。该研究得出的结果和给出的建议可为型钢拱架日光温室结构抗雪设计、稳定性研究和防灾分析提供技术指导和理论参考。     

雪荷载作用下几字型钢日光温室极限承载力分析

雪灾是导致日光温室倒塌的主要原因之一。为探明几字型钢日光温室在雪荷载作用下的失稳机理,该研究采用有限单元法,以8 m跨日光温室为研究对象,模拟其在雪荷载（均匀分布雪荷载和非均匀分布雪荷载）作用下的失稳破坏过程,计算其极限承载力,并探究纵向系杆、初始几何缺陷、截面参数对极限承载力的影响。结果表明：对于净截面面积、上翼缘宽度、腹板高度和壁厚均相同的几字型钢和空心矩形钢管,几字型钢日光温室极限承载力稍高于空心矩形钢管日光温室极限承载力;相较于均匀分布雪荷载,日光温室拱架对非均匀分布雪荷载更为敏感,非均匀分布雪荷载作用下的极限承载力约是均匀分布雪荷载作用下的28%,在日光温室结构设计中,应重点考虑非均匀分布雪荷载工况;在非均匀分布雪荷载作用下,屋脊和后屋面支座处为危险截面,最先进入全截面屈服状态;纵向系杆的设置可有效抑制结构平面外变形,进而提高结构极限承载力,有纵向系杆约束条件下的结构极限承载力约是无纵向系杆约束条件下的1.25倍;该日光温室拱架对初始几何缺陷敏感度较低,当最大初始几何缺陷幅值从5 mm增加到20 mm时,极限承载力降低约2%;在几字型钢截面选取时,在满足规范要求宽厚比前提下,建议上翼缘宽度与翻边宽度之比控制在4.17左右,腹板高度与翻边宽度之比不大于9.25,下翼缘宽度与翻边宽度之比不大于1.7,上翼缘宽度与下翼缘宽度之比控制在3.33左右,腹板高度与下翼缘宽度之比控制在4.67左右。该研究结果可为开口冷弯薄壁型钢日光温室拱架抗雪设计提供参考。     

The influence of compost and zeolite co‐addition on the nutrients status and plant growth in intensively cultivated Mediterranean soils

The main objective of the study was to test the benefits of compost and zeolite co‐addition on the fertility of organic‐rich Mediterranean soils. Previous pot study in greenhouse found that zeolites mixed with compost significantly improved potassium availability as well as exchangeable potassium capacity in the soils. To further test this finding, a field experiment was conducted using potato – Solanum tuberosum L., desiree cultivar in peat soils of the Hula Valley, Israel. Adhering to the protocol of the greenhouse experiments, the treatments included 5% compost addition with no zeolites, 2% zeolite addition without compost, co‐addition of 5% compost mixed with 2% zeolites and control. We found that compost addition increased significantly the potatoes yield and the number of large tubers; however, the zeolite addition had no impact on yield. Co‐addition of compost and zeolites did not improve total crop yield or number of large tubers compared with compost addition only. The results are consistent with nutrients availability (N, P, K) across the treatments. In a commercialized field using the experiment conditions, the 2% zeolite addition would amount to 18 ton of zeolites per hectare. Hence, we conclude that soil amendment with the tested zeolite might be beneficial to improve soil retention for cationic nutrients (e.g. K⁺) under high leaching systems such as plant culture in pots, but in the field with high loads of compost, its effect is minor.     

Evaluation of potting mix composition on potato plantlet tuber production under greenhouse conditions 1 1

Abstract

Tissue culture is currently used by many seed potato (Solanum tuberosum L.) programs enabling the production of high quality, disease free seed potatoes. Potato plantlets produced by micropropagation are planted in greenhouses to produce tubers for further multiplication in the field. The objective of this study was to develop a potting medium that would maximize potato tuber production under greenhouse conditions. Two studies were conducted evaluating different combinations of vermiculite, sand and perlite. In each study where nutrient solutions were applied weekly, vegetative weight, number of stems and potato tuber weight were evaluated. Potting media had significant effects on vegetative plant weight, number of tubers and tuber weight. Significant positive relationships between percent vermiculite in the potting mixture and number of stems (R² = 0.33? and 0.44 ) and tuber weight (R² = 0.63?? and 0.52??) were observed. In the final analysis, a potting mix containing 80% vermiculite and 20% sand provided optimum tuber production in the greenhouse. The vermiculite provided an adequate cation exchange capacity for holding nutrients and high water holding capacity while the sand provided adequate aeration.     

Windrow Composting Of Biodegradable Packaging Materials

The disintegration of Biopol-coated cardboard, polylactide fabric and film was studied using three different procedures: adding the samples directly to the compost pile, and placing them in the pile in nylon bags as well as in steel frames. Cellulose-based sausage casing, polyethylene and Mater-Bi ZF03U were also tested in steel frames as reference samples. Direct addition of the samples to the compost pile had no detrimental effect on the decomposition of compost biowaste. The use of steel frames proved to be good a method for testing samples like packaging materials. Both polylactide samples and Biopol-coated cardboard degraded completely in the steel frames. The results showed that composting activity parameters should be followed during composting before any conclusions can be made about the compostability of the samples. The compost produced from the polymer samples showed no toxicity in the plant growth test with barley and radish seeds performed at the end of the experiment.     

商陆(Phytolacca acinosa Roxb.)的锰耐性和超积累

超积累植物的确证对成功实施重金属污染环境植物修复是必不可少的。通过野外调查和营养液培养试验 ,研究超积累植物商陆 (PhytolaccaacinosaRoxb )的锰富集特性 ,结果表明 ,商陆对生长介质中的Mn具有很强的耐性和累积能力。商陆在锰含量高达 114× 10 3 mgkg-1的尾矿废弃地上依然生长良好 ,叶锰含量最高达 19 3× 10 3 mgkg-1。温室培养条件下 ,当生长介质中Mn浓度为 8 0 0 0mmolL-1时 ,虽然其生物量与对照相比有所降低 ,但植株仍能生长。随着生长介质中Mn浓度的升高 ,商陆叶和茎的Mn含量逐渐增加 ,生物富集系数则逐渐降低 ,但是地上部分锰积累量则先增加后减少。当Mn浓度为 5 0 0 0mmolL-1时 ,商陆地上部分锰积累量达到最大值 2 5 8 2mgplant-1;当Mn浓度为 12 0 0 0mmolL-1时 ,商陆仍能完成整个生命周期 ,叶锰含量达到最大值 36 4× 10 3 mgkg-1,生物富集系数为 5 5。不同锰供应水平下 ,商陆吸收的锰有87%～ 95 %被转移到地上部分。这进一步验证商陆的锰超积累特性 ,为利用超积累植物对大面积污染土壤实施植物修复提供了有力证据 ,对锰污染土壤和水体实施植物修复具有很大的应用前景     

Effects of coalbed methane‐produced water on sorghum‐sudangrass growth and soil chemical properties

Abstract

Production of methane gas from coal seams generates well water that is slightly to moderately saline. Since land application is a potential method of disposal for this water, a greenhouse study was conducted to evaluate plant response and changes in soil chemical properties resulting from irrigation with coalbed methane‐produced water. The soil was a Montevallo (Typic Dystrochrepts)‐Nauvoo (Typic Hapludults) association located in northern Alabama. Two irrigation methods used in the initial greenhouse test were 1) continuous, irrigation 24 h d^‐1 and 2) intermittent, irrigation for 12 h and off for 24 h. In a second greenhouse test, three irrigation methods were used: 1) continuous, irrigation for 24 h d^‐1, 2) intermittent, irrigation for 12 h and off for 48 h, and 3) irrigation to maintain field capacity, by daily additions of the respective irrigation water. The flow rate for continuous and intermittent irrigation treatments was 3.75 mm h^‐1. In each greenhouse test, 5 levels of salinity were generated by mixing well‐produced water with deionized water to give solutions containing 0, 10, 20, 40, and 100% well‐produced water (specific conductance (second greenhouse test) of 0.2, 1.4, 2.2, 4.4, and 9.3 dS m^‐1, respectively). Corresponding sodium adsorption ratios were 0.1, 27, 36, 55, and 81, respectively. Sorghum‐sudangrass [Sorghum bicolor (L.) Monech] was harvested for forage yields and chemical analysis at 14–30 days after initiation of irrigation treatments. Results from these preliminary short term, greenhouse studies show that coalbed methane produced water that is typical for Alabama (total dissolved solids ≤2000 mg L^‐1) can be applied to highly weathered soils. The results indicate that plant growth of summer annual grasses will be optimized if an irrigation system is used to apply produced water at a rate to maintain soil moisture at or near field capacity.     

连栋温室钢结构框架稳定设计方法

在生产性连栋温室的结构设计中,稳定性分析是设计的关键,中国目前主要采用工业与民用建筑中传统的钢结构稳定性设计理论进行结构分析,既不能真实反映出温室这种薄壁小截面结构的真实力学反应特征,也增加了温室用钢量。该文利用当前钢结构稳定设计的最新理论研究和实践成果,在详细分析传统的计算长度系数法和修正计算长度系数法利弊的基础上,针对生产性连栋温室钢结构所具有的等高、有侧移失稳时具有整体失稳的特性,通过理论分析和大量的有限元计算比较,提出了一种能够考虑柱与柱相互作用的修正计算长度系数法和层稳定系数法。在当前温室中柱和边柱普遍采用不同截面的情况下,利用该文的方法对温室钢结构框架进行设计,可以取得较好的技术和经济效果。     

基于改进最小化SNAP的植保无人机作业轨迹优化算法

轨迹优化是实现植保无人机自主作业路径规划的重要环节，合理高效的轨迹优化算法能使植保无人机安全快速地跟踪轨迹作业，提升作业稳定性与精准性。针对传统最小化SNAP算法偏移误差较大、时间分配不合理的问题，该研究提出一种针对植保作业场景的改进最小化SNAP轨迹优化算法。首先，运用机载载波相位差分(real-time kinematic,RTK)模块采集作业地块地形数据并搭建三维空间地图，基于空间地图采用牛耕法规划初始作业路径；其次，通过改进最小化SNAP算法优化作业路径，结合初始轨迹状态参量构建时间分配函数，解算得到当前最优时间分配；然后，重构最小化SNAP轨迹约束函数，添加位置偏移量梯度惩罚因子，采用最优化方法求解轨迹多项式系数；最后，联合无人机位置控制周期与轨迹多项式实例化航迹点，作为无人机运动的位置期望。试验结果表明，相较于传统最小化SNAP算法，本文算法在同等作业时间前提下，平均加速度减小7.82%，平均偏移误差减小45.56%，对轨迹偏移的抑制效果明显，并降低了加速度在地头转向处的超调，作业轨迹更加精准，作业速度更加平稳，可为植保无人机的轨迹优化策略提供参考。     

Minimal exchangeable potassium status of fifteen smectitic soils in relation to potassium uptake and plant mobilization rate of soil reserve potassium

Abstract

A greenhouse experiment was conducted to study the minimal exchangeable potassium (minimal K) status of fifteen smectite dominant soils and its relationship with K uptake and plant mobilization rate of soil reserve K. Exchangeable K reached minimal level decreasing about 35% from initial K status after 350 days of continuous cropping. Soils with high clay content and initial K status showed higher minimal exchangeable K. Cumulative K uptake by six successive crops varied from 160 mg kg^‐1 to 823 mg kg^‐1 and plant mobilization of soil reserve K varied from 0.151 mg kg^‐1 day^‐1 to 1.880 mg kg^‐1 day^‐1 among soils. Minimal K explained well the variation in total K uptake (r=0.85) and plant mobilization rate (r=0.83) as compared to initial exchangeable K status of soils (r=0.67 and 0.59, respectively) suggesting that the former is a better index of K supplying capacity of soils than the later.