Can Non-fumigant Nematicides Be an Alternative to Fumigation on Carrot Fields?

ABSTRACT

Root-knot nematodes (RKN; Meloidogyne spp.) cause enormous yield reductions in vegetable crops. While nematicides are the most effective method for controlling RKN in carrot (Dacatus carota), the efficacy of non-fumigant nematicides, compared to fumigants, is still not fully understood. The objective of this study was to evaluate the effect of 1,3-dichloropropene, a fumigant nematicide, and fluensulfone, a non-fumigant nematicide, on RKN control and yield of fresh market and processing carrot. Field experiments were conducted in a commercial farm in Lenox, GA. A randomized complete block design (r = 4) was used in a factorial arrangement of 3 nematicide treatments and 2 carrot cultivars. Nematicide treatments were the application of 1,3-dichloropropene, fluensulfone, and untreated control. Carrot cultivars were Baltimore (fresh marketing) and Belgrado (processing). In general, RKN population was low early season, averaging 0.8 RKN 100 cm^?3 of soil. RKN populations increased with crop development and there were significant differences among nematicide treatments. At harvest, RKN populations were lower for fluensulfone (1.1 RKN 100 cm^?3 of soil) and 1,3-dichloropropene (3.2 RKN 100 cm^?3 of soil) compared to Control (26.4 RKN 100 cm^?3 of soil); however, fluensulfone (91,278 kg ha^?1) had higher yield than 1,3-dichloropropene (64,154 kg ha^?1) and Control (61,908 kg ha^?1). Carrot cultivars were similar for RKN population and yield. Overall, the non-fumigant nematicide was more beneficial for carrot production than the fumigant nematicide.     

玉米/蒜苗套作系统中土壤微生物和土壤酶状况分析

对玉米蒜苗套作根区进行隔膜、隔网和无隔处理以及各自单作处理,通过处理间的相互比较,分析影响套作产量的主要土壤因素。结果表明:套作蒜苗土壤微生物上升其主要原因是根系间的非接触物质交换;套作玉米除此外,地上部环境的改变也使根部土壤微生物数量上升。根系间的非接触效应还使蒜苗、玉米土壤过氧化氢酶、蔗糖酶活性提高,而环境因素的改变也使玉米过氧化氢酶,蒜苗脲酶活性提高。相关性分析表明:微生物对蒜苗根际土壤酶活性的影响大于对玉米土壤酶的影响。     

省级水土保持补偿费征收使用管理办法及收费标准制定浅析

随着社会建设进程的加快,在生态文明逐步成为现阶段社会建设新主题的背景下,如何兼顾经济、社会快速发展和生态文明建设将是我国长期面临的局面。水土保持作为生态文明建设的重要组成部分,依法依规征收、使用水土保持补偿费是做好水土保持工作的一项基础内容,在促进水土流失预防和治理、改善生态环境方面显得尤为重要。本文就如何制定省级水土保持补偿费征收使用管理办法及收费标准(以下简称“办法”及“标准”)进行浅析,将对后续相关管理办法和收费标准的出台起到一定的指导作用,以更好地服务水土保持工作及生态文明建设。     

Essential oils from plants and in vitro shoots of Hypericum androsaemum L

The essential oil yields obtained by hydrodistillation of the aerial parts of Hypericum androsaemum cultivated plants varied from 0.94 to 4.09 mg/g of biomass dry weight, depending of the harvest time. The respective analyses performed by gas chromatography and gas chromatography-mass spectrometry revealed more than 80 compounds, 72 of which were identified. Most of the compounds were sesquiterpene hydrocarbons, which, depending of the harvest time, corresponded to 43-78% of the total essential oil. The other compounds were distributed as monoterpene hydrocarbons, oxygen-containing sesquiterpenes, n-alkanes, 1-alkenes, and oxygen-containing monoterpenes, these being a minor group. In H. androsaemum in vitro shoots, sesquiterpene hydrocarbons represented >80% of the respective essential oil. Differences in the essential oil composition were found depending on the harvest time and origin, in vivo versus in vitro, of the plant material. The essential oil sampled in November was characterized by the highest levels of sesquiterpene hydrocarbons and a high number of n-alkanes and 1-alkenes, from C(18) to C(28), whereas that sampled in June of the following year showed the highest levels of n-nonane and 1-octene as well as monoterpene hydrocarbons, the second most representative group.     

噻虫嗪在农田土壤中环境行为的研究进展

噻虫嗪是当前全球销售量最大的新烟碱类农药之一，随着噻虫嗪的广泛使用，噻虫嗪在土壤环境中的迁移转化和归宿问题成为研究热点。本文总结了噻虫嗪对陆生生物（蜜蜂、蚕、蚯蚓、鹌鹑）、水生生物（藻类、大型溞、斑马鱼等）以及土壤微生物的影响，系统综述了噻虫嗪在农田土壤中的残留、降解、吸附解析以及迁移与淋溶等环境行为及主要影响因素，并指出了噻虫嗪在农田土壤中环境行为相关研究存在的不足以及未来研究应该关注的重点和方向，以期为噻虫嗪的科学安全使用以及保障农田土壤生态环境健康提供科学依据。     

Phosphatase activity, microbial phosphorus, and fine root growth in forest soils in the Sierra de Gata, western central Spain

Acid phosphatase activity (APA), labile P fractions and fine root growth were studied in an oak (Quercus pyrenaica Willd.) forest in the Sierra de Gata, in western central Spain. Soils in the region are acid and rich in organic matter, with low levels of extractable inorganic P but with a high proportion of organic P. In such soils, the activity of phosphatase enzymes is likely to be important for the control of P mineralization and P cycling and, consequently, can affect the availability of P for plant uptake. The biomass of fine roots was about 25-fold that of leaf litter, demonstrating a high allocation of C resources to the root system in order to compensate for a low availability of soil nutrients. The study compared plots fertilized with triple superphosphate (100 kg P ha^-1) to control (unfertilized) plots. Fertilizer application had no significant effect on APA and fine root density; however, there were significant differences in available and microbial P. Spatial and seasonal variations in the APA were related to plant root density and biotic demand. Seasonal differences in the APA may also be the consequence of changes in the amount of hydrolysable organic substrates at different times of the year.     

区域土地资源安全评价初探——以重庆市为例

针对土地资源利用过程中出现的粮食安全问题、土地生态质量问题及土地经济、社会安全问题,参照压力一状态一响应(PRS)评价模式,构建评价指标体系。采用层次分析法确定权重,运用二次函数综合的方法对区域土地资源安全程度作了评价。研究表明,重庆市土地资源处于初步安全状态,从1999年和2004年土地综合安全值来看,土地资源安全整体状况处于好转之中。     

国外开发和保护水资源的经验

合理开发、利用和管理水资源，已成为世界各国所普遍关注的问题。为了缓解日益突出的水资源供求矛盾，各国进行了长期不懈的探索，在实践中总结出许多很有成效的经验。归纳起来主要有：加强立法保护水文生态环境，提高民众节水意识，实行适度开发需求管理的用水体制，推广先进的节水灌溉技术，蓄积利用雨水以及控制水体污染等，这些做法值得我国在加强水资源的开发利用和保护方面参考借鉴。     

玉米秸秆厌氧产氢工艺参数优化

为解决玉米秸秆结构致密导致秸秆发酵难于直接降解的问题,首先分别采用0.2%、0.4%、0.6%、0.8%的HCl溶液对其进行预处理,以厌氧活性污泥为接种物进行中温(38℃)发酵产氢试验。结果表明,玉米秸秆的累积产氢量和产氢速率随着盐酸质量分数的增大先增加后降低,0.6%HCl处理效果最佳,单位累积产氢量和产氢速率分别为87.90 m L/g和3.05 m L/(g·h)。再以0.6%HCl溶液预处理的玉米秸秆为底物进行发酵产氢的单因素和正交试验,研究了秸秆粒径、底物浓度、初始p H值对玉米秸秆厌氧发酵产氢过程的影响。结果表明:玉米秸秆粒径越小越利于发酵产氢;适度增加底物浓度可增加产氢量;适宜的发酵初始p H值有利于产氢细菌的生长繁殖;得到较佳的工艺参数组合为秸秆粒径150μm、底物浓度15 g/L、初始p H值为7,此时累积产氢量为112.87 m L/g。     

H5N1亚型禽流感病毒血凝素在昆虫杆状病毒系统中表达与活性鉴定

摘要：本实验从质粒pGEM-HA中扩增H5N1亚型禽流感病毒HA基因，构建转移载体pFastBacHT-HA并与E.coliDH10Bac中的Bacmid质粒重组，构建重组转座质粒rBacmid-HA。在脂质体介导下将rBacmid-HA转染sf9昆虫细胞获得重组杆状病毒。在sf9昆虫细胞中表达HA蛋白，通过SDS-PAGE、Western blot和血细胞吸附实验鉴定重组蛋白。结果显示重组HA蛋白分子量约为66kDa，该蛋白与AIV H5亚型鸡血清发生特异性反应，与H7、H9亚型鸡血清不反应，转染重组杆状病毒后的细胞能吸附鸡的红血球，证明HA基因在sf9昆虫细胞中获得了正确表达，不仅具有型特异性，而且有良好的生物反应性。