黄土丘陵植被恢复区不同植被类型对土壤物理性质的影响

通过对比研究了山西吴起县植被恢复区不同植被类型的林草地和农田的土壤物理性质,包括土壤容重、土壤孔隙度、土壤水稳性团粒结构。结果表明:不同植被类型的土壤容重为1.17~1.21 g/cm3,差异较小,但均比农田(1.31 g/cm3)低约11%,不同植被类型地各层土壤不同粒径的土壤团粒结构百分含量高于相应的天然草地和农田。实施植被修复后,与农田相比,林地土壤物理性质得到明显改善,混交林的土壤物理性质好于纯林林,天然草地和农田较差,天然草地略好于农田。     

基于L-系统的虚拟植物生长模型设计

现代农业发展需要植物生长模拟技术的支持,而迅速发展起来的虚拟植物模拟也成为研究作物生长领域的一个热点。为此,研究了L-系统方法用于描述虚拟植物生长的表达机制。基于植物形态的分形特征,采用L-系统方法,在虚拟植物生长方面,结合计算机图形学技术的有力支持,对植物生长过程进行了模拟研究。     

我国航空植保技术的发展前景

介绍了国际上先进的、具有代表性的农业航空及航空植保技术的现状,以及我国目前植保机械及航空植保使用现状,提出了我国航空植保技术发展的一些想法。     

大豆蚜为害损失估计数学模型研究

根据前人提出的为害量、为害当量观点,提出连续种群下为害当量的含义,给出为害当量的理论模型,修正了累计蚜量的偏差,提出产量损失估计的数学表达式,讨论了模型参数的田间设计方法。     

电容式植物含水监测传感器的数学建模及电路设计

国内目前的农业灌溉过程中,主要利用土壤和环境湿度来判断作物缺水状况。在研究平行板电容传感器工作原理的基础上,提出了用电容传感器测量植物含水情况,并提出在测量中将电容极板间被测物质和间隙空气抽象为固、液、气三相的方法,理论上分别建立了用于植物水分测量的三相介质的并联、串联数学建模,并做了数值模拟分析。分析认为在一定的激励信号作用下,平板电容的电容值与极板间被测介质含水率呈对应关系,得出了平行板电容传感器可以实现直接针对植物含水情况测量的结论,解决了间接测量的滞后性和准确性差的问题,确定了三相介质并联的建模方法可以作为传感器系统理论分析的最佳方案。在理论分析可行的基础上对传感器电路结构设计做了初步分析、介绍。     

我国厌氧发酵处理城市污水剩余污泥研究进展

城市污水处理剩余污泥已经成为一个严重的环境包袱,厌氧发酵减量化是目前常用的处理途径。厌氧发酵获得能源被看成未来非常有前途的领域,但目前存在效率低和仍然存留大量残渣问题。本文对国内厌氧发酵处理城市污水剩余污泥方面的研究进行了综述。包括：1．控制发酵条件和工艺提高发酵产能效率;2．对剩余污泥作前期预处理（主要有酸、碱处理,热处理,超声波处理等）,促进污泥中难降解有机物的利用;3．发酵后剩余残渣用于农田施肥的效应;4．发酵后剩余残渣用于建材（砖或陶瓷）生产原料等。     

排水工程对三江平原湿地流域的影响分析

在三江平原别拉洪河流域地形图、土地利用图和排水工程建设资料的基础上,利用地理信息系统进行流域景观制图,并根据排水工程建设量将该流域划分出4个排水分区。利用景观结构分析软件FRAGSTATS分别计算了各分区2个时期(1967年和2005年)的多种景观结构指标。结果表明:排水工程之前,除了旱地无排区的其它3个排水区域,自然湿地覆盖率均达到90%以上,且呈大块连续状分布,结构比较简单,自然状态保存完好;排水渠大量修建之后,沼泽地因排水基本消失,草甸及其它沼泽类型也大片被排干,取而代之的是以大面积的旱地和水田为基质,湿地以小的斑块体镶嵌其中的流域景观,景观结构破碎化严重并趋于复杂化。最后提出下一步的研究工作。     

机器视觉技术在精细农业中的研究进展

精细农业以节约投入、增加产出、提高投入物利用率、减少环境污染为目的.快速、准确地采集各种农田信息,有效地监测农业对象是实施精细农业的重要基础.机器视觉技术由于其非破坏性、精度高、成本效率高、信息量大、灵活等特点,在精细农业中得到了广泛的应用.为此,通过对大量参考文献进行分析,发现机器视觉在精细农业中的主要研究方向集中在农业机械自动导航、作物生长信息检测、变量控制等方面.同时,对机器视觉技术在上述领域中的研究情况进行分析和总结,并讨论了未来机器视觉技术在精细农业中应用存在的问题以及发展前景.     

烟气脱硫泵在我国农村小火电厂应用探讨

通过对目前我国农村现有的小火电厂现状进行分析,找出其落后原因以及对环境造成污染的因素.结合目前国家相关政策,对火电厂进行烟气脱硫改造,并通过对烟气脱硫泵发展和结构的研究,指出烟气脱硫泵在农村小火电厂技术改造中占有重要作用.     

Deficit irrigation based on drought tolerance and root signalling in potatoes and tomatoes

Agriculture is a big consumer of fresh water in competition with other sectors of the society. Within the EU-project SAFIR new water-saving irrigation strategies were developed based on pot, semi-field and field experiments with potatoes (Solanum tuberosum L.), fresh tomatoes (Lycopersicon esculentum Mill.) and processing tomatoes as model plants. From the pot and semi-field experiments an ABA production model was developed for potatoes to optimize the ABA signalling; this was obtained by modelling the optimal level of soil drying for ABA production before re-irrigation in a crop growth model. The field irrigation guidelines were developed under temperate (Denmark), Mediterranean (Greece, Italy) and continental (Serbia, China) climatic conditions during summer. The field investigations on processing tomatoes were undertaken only in the Po valley (North Italy) on fine, textured soil. The investigations from several studies showed that gradual soil drying imposed by deficit irrigation (DI) or partial root zone drying irrigation (PRD) induced hydraulic and chemical signals from the root system resulting in partial stomatal closure, an increase in photosynthetic water use efficiency, and a slight reduction in top vegetative growth. Further PRD increased N-mineralization significantly beyond that from DI, causing a stay-green effect late in the growing season. In field potato and tomato experiments the water-saving irrigation strategies DI and PRD were able to save about 20-30% of the water used in fully irrigated plants. PRD increased marketable yield in potatoes significantly by 15% due to improved tuber size distribution. PRD increased antioxidant content significantly by approximately 10% in both potatoes and fresh tomatoes. Under a high temperature regime, full irrigation (FI) should be undertaken, as was clear from field observations in tomatoes. For tomatoes full irrigation should be undertaken for cooling effects when the night/day average temperature >26.5 °C or when air temperature >40 °C to avoid flower-dropping. The temperature threshold for potatoes is not clear. From three-year field drip irrigation experiments we found that under the establishment phase, both potatoes and tomatoes should be fully irrigated; however, during the later phases deficit irrigation might be applied as outlined below without causing significant yield reduction:

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Potatoes

°

After the end of tuber initiation, DI or PRD is applied at 70% of FI. During the last 14 days of the growth period, DI or PRD is applied at 50% of FI.

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Fresh tomatoes

°

From the moment the 1st truce is developed, DI is applied at 85-80% of FI for two weeks. In the middle period, DI or PRD is applied at 70% of FI. During the last 14 days of the growth period, DI or PRD is applied at 50% of FI.

•

Processing tomatoes

°

From transplanting to fruit setting at 4th-5th cluster, the PRD and DI threshold for re-irrigation is when the plant-available soil water content (ASWC) equals 0.7 (soil water potential, Ψ_soil = −90 kPa). During the late fruit development/ripening stage, 10% of red fruits, the threshold for re-irrigation for DI is when ASWC = 0.5 (Ψ_soil = −185 kPa) and for PRD when ASWC (dry side) = 0.4 (Ψ_{soil, dry side} = −270 kPa).

The findings during the SAFIR project might be used as a framework for implementing water-saving deficit irrigation under different local soil and climatic conditions.