增硝营养对水稻不同生育时期生长及氮素吸收同化的影响

The effect of nitrate （NO3^-） on rice （Oryza sativa L.） growth as well as N absorption and assimilation during different growth stages was examined using three typical rice cultivars. Dry weight, yield, N uptake, nitrate reductase activity （NRA） in leaves, and glutamine synthetase activity （GSA） in roots and leaves during their entire growth periods, as well as the kinetic parameters of ammonium （NH4^＋） uptake at the seedling stage, were measured with solution culture experiments. Results indicated that addition of NH4^＋-N and NO3^-N at a ratio of 75：25 （NH4^＋＋NO3^- treatment） when compared with that of NH4^＋-N alone （NH4^＋ treatment） increased the dry weight of ‘Nanguang＇ cultivar by 30% and ‘Yunjing 38＇ cultivar by 31%, and also increased their grain yield by 21% and 17%, respectively. For the four growth stages, the total N accumulation in plants increased by an average of 36% for ‘Nanguang＇ and 31% for ‘Yunjing 38＇, whereas the increasing effect of NO3^- in the ‘4007＇ cultivar was only found at the seedling stage, in the NH4^＋＋NO3^- treatment compared to the NH4^＋ treatment, NRA in the leaves increased by 2.09 folds, and GSA increased by 92% in the roots and 52% in the leaves of the three cultivars. NO3^- supply increased the maximum uptake rate （Vmax） in the ‘Nanguang＇ and ‘Yunjing 38＇ cultivars, reflecting that the NO3^- itself, not the increasing N concentration, increased the uptake rate of NH4^＋ by rice. There was no effect on the apparent Michaelis-Menten constant （Kin） of the three cultivars. Thus, some replacement of NH4^＋ with NO3^-could greatly improve the growth of rice plants, mainly on account of the increased uptake of NH4^＋ promoted by NO3^-, and future studies should focus on the molecular mechanism of the increased uptake of NH4^＋ by NO3^-.     

转基因棉花对土壤生态环境的影响

总结了转基因棉花在生态安全性方面的研究进展,重点介绍了转基因棉花对土壤生态环境的影响,包括：外源基因表达产物在土壤中的富集;外源基因表达产物对土壤生物的影响：外源基因在土壤生态系统中的水平转移。认为目前对转基因棉花的土壤生态学过程的研究较少,尚难以确定转基因棉花对土壤生态环境的影响程度。并由此介绍了Biolog系统和DNA指纹技术在土壤生态安全性研究中的应用。     

液体培养研究不同土壤中硝化活性

A red soil, a fluvo-aquic soil and a permeable paddy soil were used in a long-term investigation to study changes in nitrification with treatments: 1) soil incubation, 2) liquid incubation inoculated with soil samples, and 3) liquid incubation inoculated with ammonia-oxidizing bacteria (AOB) from the soils. There were significant differences (P < 0.001) in nitrification rates among the three soils when measured for 28 days by adding (NH4)2SO4 at the rate of 154 mg N kg-1 dry soil to fresh soil. However, the amounts of nitrifying bacteria in the three soils were not related to soil nitrification capacity. When the soil samples or the isolates of AOB enriched from the corresponding soil were incubated in liquid with pH 5.8, 7.0 and 8.0 buffers and 10 mmol L-1 ammonium nitrogen, there were no significant nitrification differences in the same soil type at each pH. The ability to oxidize ammonia through AOB from different types of soils in a homogeneous culture medium was similar, and the soil nitrification capacity could reflect the inherent properties of a soil. Altering the culture medium pH of individual soil type also showed that acidification of an alkaline fluvo-aquic soil decreased nitrification capacity, whereas alkalinization of the acidic red soil and permeable paddy soil increased their nitrification. For a better insight into factors influencing soil nitrification processes, soil properties including texture and clay composition should be considered.     

土壤有机污染生物修复技术影响因素的研究进展

土壤有机污染的生物修复技术的论述很多,本文则从对影响这些技术实施的因素进行综合评述,例如污染物的性质、微生物自身特性等。     

Neural network ensemble residual kriging application for spatial variability of soil properties

High quality, agricultural nutrient distribution maps are necessary for precision management, but depend on initial soil sample analyses and interpolation techniques. To examine the methodologies for and explore the capability of interpolating soil properties based on neural network ensemble residual kriging, a silage field at Hayes, Northern Ireland, UK, was selected for this study with all samples being split into independent training and validation data sets. The training data set, comprised of five soil properties: soil pH, soil available P, soil available K, soil available Mg and soil available S,was modeled for spatial variability using 1) neural network ensemble residual kriging, 2) neural network ensemble and 3) kriging with their accuracies being estimated by means of the validation data sets. Ordinary kriging of the residuals provided accurate local estimates, while final estimates were produced as a sum of the artificial neural network (ANN) ensemble estimates and the ordinary kriging estimates of the residuals. Compared to kriging and neural network ensemble,the neural network ensemble residual kriging achieved better or similar accuracy for predicting and estimating contour maps. Thus, the results demonstrated that ANN ensemble residual kriging was an efficient alternative to the conventional geo-statistical models that were usually used for interpolation of a data set in the soil science area.     

基于燃烧室外预热的柴油发动机性能分析

能源匮乏和环境污染已成为当今世界各国所面临的两大难题,柴油机凭借高热效率和高可靠性得到越来越广泛的应用。利用自制的电控恒温燃油预热装置,对柴油发动机进行燃油室外预热,分别进行柴油机的负荷特性实验、速度特性实验和排气烟度实验。实验结果表明,能够改善柴油机工作性能的最佳预热温度范围为60—90℃。     

余姚地区松幽天牛发生情况及其在枯死马尾松根部分布规律的初步研究

调查了松幽天牛(Asemum amurense)在余姚地区的发生情况及其幼虫在枯死松树根内的分布规律。结果表明,松幽天牛在余姚地区1年发生1代,以幼虫在松树根内越冬。4月中旬开始化蛹,5月中旬成虫开始羽化,6月上旬成虫开始产卵,7月下旬卵开始孵化。松幽天牛在余姚地区的平均危害率达42.9%,其发生与土壤理化性质密切相关。松幽天牛幼虫在主、侧根内的分布数量差异显著,主根内的幼虫数显著多于侧根内。还依据松幽天牛的生活学特性提出了松幽天牛的防治措施     

岩木瓜根皮化学成分研究

应用柱色谱技术对岩木瓜根皮的化学成分进行了分离纯化,并对分离所得的化合物采用核磁共振及质谱鉴定了化舍物结构.从岩木瓜根皮中分离、鉴定了9个化合物,根据化合物的理化常数和波谱数据鉴定其结构,分别鉴定为β-香树脂醇乙酸酯(1)、蒲公英赛酮(2)、蒲公英赛醇(3)、2α-羟基齐墩果酸(4)、齐墩果酸(5)、β-谷甾醇(6)、...     

白发藓和大灰藓提取液对作物种子的影响

测定3种浓度梯度的白发藓、大灰藓的配子体水提液对绿豆、萝卜、甜椒、油菜、玉米5种作物种子的发芽率、胚根长、胚根重、幼苗鲜重等指标的影响。结果显示:3种不同浓度的白发藓提取液对作物种子的胚根长、胚根鲜重和幼苗鲜重均呈抑制作用;而大灰藓提取液对作物种子的胚根长、胚根鲜重和幼苗鲜重在高浓度下呈抑制作用,在低浓度下呈促进作用。2种苔藓提取液对作物种子萌发指标的影响力大小依次为:胚根长>胚根鲜重>幼苗鲜重>发芽率,胚根长是较好的生物测定指标,发芽率则是不敏感的生物测定指标。绿豆、萝卜和油菜是测定2种苔藓提取液对种子萌发影响力较好的实验材料。     

工业园区绿地系统规划浅析——以淮安工业园区绿地系统规划为例

介绍了当前我国工业园区绿地系统规划的概念及意义,并以淮安工业园区为代表,探讨了工业园区绿地系统规划的相关内容,可为我国工业园区绿地系统规划提供一定的借鉴。