泰安市茶树种植气候条件分析

利用泰安市5个气象台站1970-2004年的气候资料,结合茶树的生态学特性,探讨了泰安市气候条件对茶树生长发育和茶叶品质的影响,系统分析了有利和不利的气候因素,由此提出了泰安市茶园栽培管理技术措施和对茶叶产业发展的建议.     

陇东黄土高原春播紫花苜蓿生态气候特征及适生种植区划

根据对春播两年生紫花苜蓿生长状况和相应气象观测资料的分析，探讨了陇东黄土高原地区春播紫花苜蓿的生长发育与平均气温、积温及降水量等生态气侯条件的定量关系，据此得出陇东地区紫花苜蓿的适生种植区划和气侯风险区划。综合区划结果提出开发利用气侯资源的途径和生产紫花苜蓿的对策，为陇东地区进一步调整农业生产结构，发展畜牧业生产和改善生态环境提供依据。     

浙江省严重干旱发生年份的GM（1，1）预测模型

传统灰色GM（1，1）模型对稳定序列的中长期预测效果较好，对变化幅度较大的严重干旱年序列的中长期预测效果较差。本文采用中心逼近式灰色GM（1，1）模型，通过调整m值，使模型精度达到要求，从而建立浙江省严重干旱发生年份的GM（1，1）预测模型。拟合结果表明，该方法对预测浙江省下一个严重干旱发生年有一定的参考价值。     

Simulating management effects on crop production, tile drainage, and water quality using RZWQM-DSSAT

The objective of this study was to explore if more crop-specific plant growth modules can improve simulations of crop yields, and N in tile flow under different management practices compared with a generic plant growth module. We calibrated and evaluated the Root Zone Water Quality Model (RZWQM) with the Decision Support for Agrotechnology Transfer (DSSAT v3.5) plant growth modules (RZWQM-DSSAT) for simulating tillage (NT — no till, RT — ridge till, CP — chisel plow, and MP — moldboard plow), crop rotation {CC — continuous corn, and CS — corn (Zea mays L.)-soybean [Glycine max (L.) Merr.]}, and nitrogen (N) (SA — single application at preplant, and LSNT — late spring soil N test based application) and manure (SM — fall injected swine manure) management effects on crop production and water quality. Data from 1978 to 2003 from a water quality experiment near Nashua (Nashua experiments), Iowa, USA, were used. The model was calibrated using data from one treatment plot and validated for the rest of the plots. Simulated management effects on annual N loading in tile flow were agreeable with measured effects in 85%, 99%, 88%, and 78% of the cases for tillage, crop rotation (CS vs. CC), N application timing (SA vs. LSNT), and swine manure applications (SM vs. SA), respectively. On average, the LSNT plots were simulated to have 359 kg ha^− 1 higher corn yield compared to SA, when the observed increase was 812 kg ha^− 1. Grain yield simulations were not sensitive to differences between RT and NT, between SM and SA treatments, and between CS and CC. We conclude that considering the uncertainties of basic input data, processes in the field, and lack of site specific weather data, the results obtained with this RZWQM-DSSAT hybrid model were not much better than the results obtained earlier with the generic crop growth module.     

Fluxes of nitrous oxide and nitric oxide from experimental excreta patches in boreal agricultural soil

Nitric oxide (NO) and nitrous oxide (N₂O) emissions were measured from experimental dung and urine patches placed on boreal pasture soil during two growing seasons and one autumn period until soil freezing. N₂O emissions in situ were studied by a static chamber method. NO was measured with a dynamic chamber method using a NO analyser in situ. Mean emissions from the control plots were 47.6±4.5 μg N₂ON m⁻² h⁻¹ and 12.6±1.6 μg NON m⁻² h⁻¹. N₂O and NO emissions from urine plots (132±21.2 μg N₂ON m⁻² h⁻¹ and 51.9±7.6 μg NON m⁻² h⁻¹) were higher than those from dung plots (110.0±20.1 μg N₂ON m⁻² h⁻¹ and 14.7±2.1 μg NON m⁻² h⁻¹). There was a large temporal variation in N₂O and NO emissions. Maximum N₂O emissions were measured a few weeks after dung or urine application, whereas the maximum NO emissions were detected the following year. NO was responsible on average 14% (autumn) and 34% (summer) of total (NO+N₂O)N emissions from the pasture soil. NO emissions increased with increasing soil temperature and with decreasing soil moisture. N₂O emissions increased with increasing soil moisture, but did not correlate with soil temperature. Therefore we propose that N₂O and NO were produced mainly during different microbial processes, i.e., nitrification and denitrification, respectively. The results show that the overall conditions and mechanism especially for emissions of NO are still poorly understood but that there are differences in the mechanisms regulating N₂O and NO production.     

Using arbuscular mycorrhiza to reduce the stressful effects of soil compaction on corn (Zea mays L.) growth

Soil compaction is of great importance in agriculture, because its high levels may adversely affect plant growth and the environment. Since mechanical methods are not very efficient and economical, using biological methods to alleviate the stress of soil compaction on plant growth may be beneficial. The objectives of this study were to: (1) evaluate the effects of soil compaction on corn (Zea mays L.) growth, and (2) test the hypothesis that applying arbuscular mycorrhiza (AM) with different origins can partially or completely overcome the stressful effects of soil compaction on corn growth under unsterilized and sterilized conditions. Corn was planted in unsterilized and sterilized compacted soils, while treated with three species of AM including, Iranian Glomus mosseae, Iranian Glomus etunicatum, and Canadian Glomus mosseae, received from GINCO (Glomales in vitro Collection), Canada. Plant growth variables and soil resistance parameters were determined. AM significantly increased root fresh (maximum of 94% increase) and dry (maximum of 100% increase) weights in the compacted soil. AM with different origins may improve corn growth in compacted soils, though its effectiveness is related to the level of compaction and also to the interaction with other soil microorganisms.     

Soil compaction and forest floor removal reduced microbial biomass and enzyme activities in a boreal aspen forest soil

Soil enzymes are linked to microbial functions and nutrient cycling in forest ecosystems and are considered sensitive to soil disturbances. We investigated the effects of severe soil compaction and whole-tree harvesting plus forest floor removal (referred to as FFR below, compared with stem-only harvesting) on available N, microbial biomass C (MBC), microbial biomass N (MBN), and microbial biomass P (MBP), and dehydrogenase, protease, and phosphatase activities in the forest floor and 0–10 cm mineral soil in a boreal aspen (Populus tremuloides Michx.) forest soil near Dawson Creek, British Columbia, Canada. In the forest floor, no soil compaction effects were observed for any of the soil microbial or enzyme activity parameters measured. In the mineral soil, compaction reduced available N, MBP, and acid phosphatase by 53, 47, and 48%, respectively, when forest floor was intact, and protease and alkaline phosphatase activities by 28 and 27%, respectively, regardless of FFR. Forest floor removal reduced available P, MBC, MBN, and protease and alkaline phosphatase activities by 38, 46, 49, 25, and 45%, respectively, regardless of soil compaction, and available N, MBP, and acid phosphatase activity by 52, 50, and 39%, respectively, in the noncompacted soil. Neither soil compaction nor FFR affected dehydrogenase activities. Reductions in microbial biomass and protease and phosphatase activities after compaction and FFR likely led to the reduced N and P availabilities in the soil. Our results indicate that microbial biomass and enzyme activities were sensitive to soil compaction and FFR and that such disturbances had negative consequences for forest soil N and P cycling and fertility.     

上向流曝气生物滤池中有机氮沿程转化规律与生物特性研究

为揭示上向流曝气生物滤池中有机氮沿程转化规律及其微生物特性,优化滤池的设计与运行,以有机氮废水为处理对象,在水力负荷0.329～0.50 5m3/(m2.h)、气水比4-5:1、沿程DO 3.0～5.85 mg/L、不加任何有机碳源的情况下,研究氮元素沿程转化规律.结果表明:曝气生物滤池内有机氮氨化与硝化同步进行,90%以上的溶解性有机氮(DON)转化为NO3-N;滤池沿程各段对于TKN的降解进程(TKN→NH3-N)与NH3-N的硝化进程(NH3-N→NO2-N→NO3-N)一致:微生物总量沿水流方向呈逐渐递减趋势;生物耗氰速率(OUR)沿程逐渐减小,OUR 数量级为101mg/(g·h).该研究可为硝化滤池的设计提供理论依据以及滤池运行参数的优化提供技术支持.     

遥感及CA模型支持下的吉隆坡及其周边地区城市扩展分析与预测

利用长时间序列高分辨率Landsat TM影像,对吉隆坡及其周边地区城市扩展模式特征及驱动机制进行了分析,确定了其影响因子和限制因素,并基于CA模型原理对该研究区的城市扩展进行了模拟与预测.结果表明.吉隆坡及其周边地区城市扩展一直处于多经济核心支持下的中高速扩展阶段.吉隆坡内部的填充式扩展模式在整个城市扩展期间受周边的集中式扩展影响较大.在地形、经济及行政政策的交互影响下,研究区的扩展方向主要为西北、南、东南方向,其中以南部的城市扩展在各个时期最为突出.     

不同化感潜力水稻秧苗响应低钾的光合生理特性

本研究以化感水稻"PI312777"和非化感水稻"Lemont"为材料,采用水培方法研究低钾(5 mg K.L-1)和正常钾(40 mg K.L-1)条件下,两水稻品种的光合生理及其响应机制。结果表明,低钾条件对非化感水稻"Lemont"的根长、株高、干重有显著的抑制作用;而对化感水稻"PI312777"的根长有促进作用,对其他指标的影响较小。低钾条件下,两种水稻光合作用参数——净光合速率、胞间CO2浓度、蒸腾速率、气孔导度、气孔限制值、叶绿素含量等均下降,但非化感水稻"Lemont"下降的幅度较大,且与化感水稻"PI312777"差异显著。水稻光合作用相关酶的分析结果表明,低钾条件下核酮糖-1,5-二磷酸羧化酶、磷酸烯醇式丙酮酸羧化酶和乙醇酸氧化酶的活性及其基因表达强度均降低,但化感水稻"PI312777"的下降幅度显著小于非化感水稻"Lemont"。可见低钾条件下,化感水稻"PI312777"比非化感水稻"Lemont"具有更强的光合作用能力及耐营养匮乏能力。