Herbicides and plant hormesis

Herbicide hormesis is commonly observed at subtoxic doses of herbicides and other phytotoxins. The occurrence and magnitude of this phenomenon are influenced by plant growth stage and physiological status, environmental factors, the endpoint measured and the timing between treatment and endpoint measurement. The mechanism in some cases of herbicide hormesis appears to be related to the target site of the herbicide, whereas in other examples hormesis may be by overcompensation to moderate stress induced by the herbicides or a response to disturbed homeostasis. Theoretically, herbicide hormesis could be used in crop production, but this has been practical only in the case of the use of herbicides as sugar cane ‘ripeners’ to enhance sucrose accumulation. The many factors that can influence the occurrence, the magnitude and the dose range of hormetic increases in yield for most crops make it too unpredictable and risky as a production practice with the currently available knowledge. Herbicide hormesis can cause undesired effects in situations in which weeds are unintentionally exposed to hormetic doses (e.g. in adjacent fields, when shielded by crop vegetation). Some weeds that have evolved herbicide resistance may have hormetic responses to recommended herbicide application rates. Little is known about such effects under field conditions. A more complete understanding of herbicide hormesis is needed to exploit its potential benefits and to minimize its potential harmful effects in crop production. © 2014 Society of Chemical Industry     

Analysis on Dredger Fill Electrical Response Under Additive Electrical Field

With the purpose of the study on change rule of internal charge in soil specimens under differing circumstances, dredger fill, which was collected from Guangxi Beibu Gulf Economic Zone, was studied in various parameters, including the absence/presence of the applied DC electric field, different levels of field strength, soil water content, soil compactness, and degree of desalination. Moreover, through tentatively simulating the electrical response between thundercloud and earth mass, the triggered lightning mechanism of rock soil mass was explored. The results show that both additive electrical field and atmospheric electric field had influence over charge variation of soil, the impact of which would become more significant with the increasing field strength. Higher soil water content and lower degree of desalination could enhance the charge variation and conductivity of soil, whilst this action effect would remain stable when soil water content reached a certain degree. Although soil compactness make some effect for the charge distribution, its regularity is undefined so far.     

微生物菌剂对农业废弃物腐熟进程影响研究

以蔬菜秸秆、西红柿蔓和牛粪为原料,添加自制速腐菌剂,并用未添加菌剂的常规处理做对照组,定期通气和搅拌,研究接种菌剂对腐熟进程的影响。结果表明,接种菌剂的组温度较高,高温持续时间较长;实验组高温期CO2释放量较对照组高,pH值和电导率变化趋势大,其中的微生物活动强烈;NH3释放量较对照组低,有利于减少氮损失;实验组有机质的减少幅度较对照组大,添加菌剂能够提高腐熟过程消解废弃物的能力,加快蔬菜秸秆和牛粪的腐熟进程。     

混合动力车用汽油机效率模型研究

混合动力车用汽油机效率模型能够解决因不确定的油耗特性导致其发动机控制准确性难以保证的难题。通过理论分析和对LJ491QE1型、DA4G18-AA型汽油机的大量试验研究,提出换气当量损失和换气经验当量损失作为通用效率模型,用于确定混合动力车用自然吸气、进气道喷射式汽油机动态变化的高效工作区理论;换气经验当量损失仅利用进气压力、排气压力两个参数,就能准确地确定自然吸气、进气道喷射式汽油机动态变化的高效工作区,并且较换气当量损失具有更好的响应性。     

时域反射仪测定高含盐土壤盐分研究

采用室内试验的方法,通过使用时域反射仪(TDR100)测定不同含盐量及不同含水率土样的电导值,与采用电导率仪测定的土壤溶液电导值及烘干法测得的含水率值进行比较。结果表明,它们之间存在显著的线性关系。并根据测定结果得到标定公式,提出使用TDR测定高含盐量土壤含盐量的方法。试验结果可为河套灌区野外测定土壤含盐量提供参考。     

220kV降压变电所电气部分初步设计

变电所是电力系统极其重要的组成部分,其合理设计与建设可以保证供电的可靠性和满足远期负荷的要求。设计一个220kV地区性降压变电所,主要向地方负荷供电。介绍该变电所的原始资料,阐述其电气部分主变压器的选择和电气主接线的拟定设计,为此类变电所的设计提供理论参考。     

Effects of dietary levan on growth performance,nonspecific immunity,pathogen resistance and body composition of orange‐spotted grouper (Epinephelus coioides H.)

This study investigated the effects of levan produced by Bacillus licheniformis FRI MY‐55 on growth performance, intestinal count of viable bacteria, immune status, pathogen resistance and body composition of orange‐spotted grouper (Epinephelus coioides). Orange‐spotted grouper were fed diets supplemented with levan at concentrations of 0 (control), 5.0, 10.0, 25.0 and 50.0 g kg^?1 for 12 weeks. The final weight and per cent weight gain were significantly higher in the 25.0 g kg^?1 levan‐supplemented group than in the control group (p < 0.05). All levan‐supplemented diets significantly decreased the count of total viable aerobic bacteria and Vibrio spp. in the intestines of groupers (p < 0.05). Serum total protein levels, globulin levels, lysozyme activity and survival rate of orange‐spotted grouper after challenge with V. harveyi were significantly higher in the 25.0 g kg^?1 levan‐supplemented group than in the control group (p < 0.05). This study also found that the 10.0, 25.0 and 50.0 g kg^?1 levan‐supplemented diets significantly increased the crude protein level in the body composition of orange‐spotted grouper. Overall, the results of this study indicate that dietary levan (25.0 g kg^?1) could be an effective method for enhancing the growth performance and disease resistance in orange‐spotted grouper.     

高酸海棠苗木抗寒性生理指标的分析

为了研究高酸海棠栽种适宜区域,用高酸海棠新品种‘冰心1 号’、‘红勋1 号’与现有品种‘新苹1号’进行抗寒性比较,以枝条作为试验材料进行低温处理,并根据外渗电导法、脯氨酸及丙二醛(MDA)含量的变化,研究了各样品的抗寒性能。通过试验测定结果可判定3 个样本的相对电导率大小依次为‘新苹1 号’＞‘红勋1 号’＞‘冰心1 号’,脯氨酸含量由高到低的顺序依次为‘冰心1 号’＞‘红勋1 号’＞‘新苹1 号’,MDA含量大小的总体趋势依次为‘红勋1 号’＞‘新苹1 号’＞‘冰心1 号’。总体而言,‘冰心1号’的抗寒性最强,3 个品种的抗寒顺序依次为‘冰心1 号’＞‘红勋1 号’＞‘新苹1 号’。其中‘冰心1 号’与‘红勋1号’都具有较强的耐寒能力,适宜栽种于新疆天山以北及其他寒冷区域。     

高职电工技术教学模式改革的探索

高职院校现已将电工技术这门课程为基础专业课程。掌握好这门课程的基础知识和实践技能,对于高职学生以后进一步学习和以后的发展,将起到非常重要的作用。因此根据当前电工技术这门课程发现比较普遍和严重的问题,结合现实的课程教学内容,笔者将从课程的内容和教学方法、以及教学实践这几方面考虑做出比较符合现在需求的研究和探索。