大气CO2和O3升高对菜地土壤酶活性和微生物量的影响

利用OTC平台和青菜盆栽实验,探索[CO2]、[O3]或[CO2+O3]升高条件下,土壤理化性质、微生物量和土壤酶活性的变化,以期获得未来大气CO2或/和O3升高对土壤微生态系统的风险性。结果表明,[CO2]升高不同程度地提高了土壤的可溶性有机碳（DOC）、可溶性有机氮（DON）、总磷（TP）、总碳（TC）、铵态氮（AN）、硝态氮（NN）含量和含水量（SWC）,进而不同程度地提高了土壤微生物量碳（MBC）、微生物量氮（MBN）含量以及土壤蛋白酶（PRA）、蔗糖酶（SA）、脲酶（UA）、多酚氧化酶（POA）、酸性磷酸酶（APA）和中性磷酸酶（NPA）活性。相反,[O3]升高不同程度降低了土壤DOC、TP、TK、TC、TN、AN、NN、SWC、MBC和MBN含量,提高了MBC/MBN比值,在不同程度上降低了土壤PRA、SA、UA、POA、APA和NPA酶活性。而[CO2+O3]在一定程度上消减了[O3]对土壤微生物量和酶活性的抑制作用,也降低了[CO2]升高对土壤微生物量和酶活性的刺激效应。因此,土壤微生物量和土壤酶活性的变化可用于评价未来大气CO2或/和O3升高对菜地土壤微生态环境的影响。     

Effects of ambient gaseous pollutants on photosynthesis,growth, yield and grain quality of selected crops grown at different sites varying in pollution levels

In recent decades, ambient gaseous pollution has increased due to anthropogenic activities worldwide. The studies to evaluate the adverse effects of ambient pollutants on commonly grown food crops are still limited, especially in Asian countries like Pakistan. The present study was conducted to measure the ambient pollutants in different sites of Faisalabad and their impact on growth and yield of wheat, mung bean and peas. Plants were grown in pots and placed at three sites named as control (Wire house of Government College University, Faisalabad), low pollution (LP) (Farm Area of Ayub Agricultural Research Institute) and high pollution (HP) (GT Chowk, Faisalabad) sites. Results showed that ambient ozone (O₃) concentration was highest at HP site followed by LP site and was below AOT40 in control site. Ambient pollutants caused foliar injury in crops and decreased plant height, leaf area, biomass and grain yield. Pollutants caused a reduction in photosynthetic pigments, stomatal conductance and net photosynthetic rate and grain protein contents in all three crops. In conclusion, the ambient O₃ level was highest at HP site, this current O₃ level and other pollutants decreased the growth and yield of important food crops.     

水稻拔节期根系呼吸对臭氧污染和厌氧—有氧环境变化的响应

依托O3FACE(Free-Air O3 Enrichment)研究平台,研究了大气臭氧(O3)浓度增加对拔节期水稻根系呼吸和生物量积累分配的影响,利用特制集气装置分析了厌氧—有氧条件对根系呼吸的影响。结果表明,O3浓度升高水稻冠层和总生物量略有降低,而根干物重和根/冠比分别显著降低14.7%和10.4%。9∶1和9.5∶0.5的纯N2∶O2配比利于根系呼吸,纯N2或空气、CO2饱和蒸馏水条件不同程度降低了根系呼吸速率;高臭氧处理、对照处理的水稻根系呼吸速率分别在CO2饱和蒸馏水、纯N2条件下最小,表明尽管不同根系测定条件影响根系呼吸速率,但影响程度也受植物生长的大气环境制约。臭氧污染处理水稻根系的呼吸速率在气态测定条件下显著高于正常大气处理23.6%～52.7%,在CO2饱和蒸馏水测定条件下未达到显著水平,臭氧污染效应明显降低。两个环境生长的水稻根系呼吸均随测定根系气态环境供氧量的增加呈凸二次函数变化,5%～10%比例的氧气供应促进了根系呼吸,较强的厌氧环境(纯N2)和有氧环境(Air)均不利于水稻根系呼吸。     

地表臭氧胁迫对冬小麦籽粒品质的影响研究

为深入探讨地表臭氧（O3）对冬小麦品质的影响,采用开顶式气室（OTC）,设置3个处理组：CK（对照组）、CF100（O3浓度为100 nL·L-1）、CF150（O3浓度为150 nL·L-1）,通过大田试验和实验室分析,开展了O3浓度增加对冬小麦蛋白质及其组分、氨基酸及其组成、淀粉含量等营养品质和加工品质的影响研究。结果表明：①籽粒氨基酸总量依次为CF100〉CF150〉CK,而人体所需的必需氨基酸总量为CF150〉CF100〉CK,处理间均差异显著（P〈0.05）。②粗蛋白含量随O3浓度的升高而增加,但各组分间变化趋势不同：清蛋白、球蛋白的含量为CF150〉CF100〉CK,醇溶蛋白、谷蛋白的含量则为CF100〉CF150〉CK。③淀粉含量随着O3浓度的升高而降低,两者呈显著负相关（P〈0.05）,与CK相比,CF100、CF150冬小麦淀粉含量分别下降了4.06%和16.61％。可见,O3胁迫能促进籽粒营养品质和加工品质的合成。     

Tundra plants protect the soil surface from UV

In the Arctic, seasonal ozone depletion is resulting in periods of enhanced UV-B radiation at ground level while regional climate change is associated with increasing temperatures. These changes are likely to alter plant distribution, biodiversity and morphology, which may have knock-on effects for microbially driven biogeochemical cycling and other soil processes. Our study examined the transmission of solar UV radiation through arctic tundra plants using a portable UV radiometer and the DLR-biofilm biological UV dosimeter. A strong negative correlation was found between vegetation cover and UV transmission to the soil surface. Penetration of UV to the soil beneath tundra plants varied depending upon plant morphology, being greater through low creeping plants than cushion plants, grasses or mosses. UV transmission to the soil surface beyond the foliage edge also varied with plant morphology and the presence of flowers.     

对臭氧在温室蔬菜生产上应用的质疑

该文综合分析国内外有关近地面臭氧伤害作物,臭氧污染呈上升趋势的资料,以及对温室臭氧状况做尝试性监测后认为,因光化学反应,温室环境会存在臭氧污染,其浓度有可能达到伤害作物的程度.温室臭氧规律有待深入调查.温室中使用臭氧气体防治病虫害是个错误.     

有机基质臭氧消毒设备设计与试验

为实现有机基质的绿色、高效消毒,设计了有机基质臭氧消毒设备。基于离散元软件EDEM建立了有机基质颗粒模型,根据有机质物料输送及抛撒动力学特性与臭氧消毒工艺流程,利用Solid Works软件构建了有机基质臭氧消毒设备结构模型,并对两种模型进行接触参数标定。以有机基质倾尽角为评价指标,以抄板弯折角、转筒转速、填充率为试验因素,进行了三因素五水平正交旋转组合仿真试验。根据仿真结果,利用Design-Expert软件回归分析法建立倾尽角回归数学模型,对有机基质臭氧消毒设备模型中的抄板弯折角、转筒转速、填充率进行了参数优化与试验验证。结果表明,在各因素取值范围内,抄板弯折角对有机基质倾尽角影响极显著,转筒转速对倾尽角影响显著,填充率对倾尽角影响不显著;有机基质臭氧消毒装置最优作业参数组合为:抄板弯折角124.23°、转筒转速6.29 r/min,此时物料倾尽角仿真值为89.3°。臭氧消毒灭菌性能试验验证结果为:臭氧初始质量浓度64.2 mg/m~3,消毒60 min后,细菌灭菌率88.9%,真菌灭菌率97.9%,能够满足有机基质消毒生产要求。     

Nitrogen and phosphorus use in maize sole cropping and maize/cowpea mixed cropping systems on an Alfisol in the northern Guinea Savanna of Ghana

Summary The use of N and P by mixed and by sole cropping (crop rotation) of maize and cowpeas were compared in a field experiment on an Alfisol at the Nyankpala Agricultural Experiment Station in the northern Guinea Savanna of Ghana, using two levels of N (0 and 80 kg N ha^-1 year^-1 as urea) and P application (0 and 60 kg P ha^-1 year^-1 as Volta phosphate rock). Maize grain yields were significantly reduced in the mixed cropping system. This yield difference became smaller with the application of N and P fertilizer. The N and P concentrations in maize ear leaves at silking indicated that a deficiency in N and P contributed to the maize yield depression in mixed cropping. Competition for soil and fertilizer N between maize and cowpeas was suggested by: (1) A similarity in total N uptake between the two cropping systems; (2) efficient use of soil nitrate by the cowpeas; and (3) low N₂ fixation by the cowpeas, calculated with the aid of an extended-difference method. In general, N₂ fixation was low, with the highest values in the sole cropping (53 kg ha^-1) and a substantial reduction in the mixed cropping system. The application of N fertilizer further reduced N₂ fixation. This was substantiated by nodule counts. The lower N₂ fixation in the mixed cropping system was only partly explained by the lower density of cowpeas in this system. In addition, dry spells during the cropping season and shading by the maize component could have reduced the nodulation efficiency. No N transfer from the legume/rhizobium to the non-legume crop was observed. Impaired P nutrition in the mixed compared with the sole-cropped maize might have been due to less P mobility in the soil. This was indicated by lower soil moisture contents in the topsoil under mixed cropping, especially during the dry year of 1986. The results show that mixed cropping of maize and cowpeas did not lead to improved use of soil and fertilizer N and P or to an enhanced N₂ fixation. On the contrary, an annual rotation of maize and cowpeas was clearly superior.     

基于土壤消退指数的田间土壤水分预报方法的研究

在分析现有的土壤水分预报方法的基础上,研究了不同深度的大田土壤水分消退指数随作物生长时间的变化规律,探讨了冬小麦生育期土壤墒情预报的经验递推方法,通过研究表明:利用土壤水分消退法来进行田间土壤水分预报,具有方法简单,所需参数较少且容易获取,预报结果可靠,精度较高的优点,可以满足灌溉预报的要求。     

总可捕量制度在我国的可行性分析

本文在论述总可捕量制度的定义、实施总可捕量制度需要具备的必要条件等内容的基础上，指出我国实施总可捕量制度的必然趋势及存在的困难。并提出了我国实施总可捕量制度的四点建议和设想：（1）大力实施减船措施，（2）加强渔业资源的调查与研究，（3）加强渔政执法，重视监督管理，（4）由点到面逐步实施TAC制度。