The Effect of Detopping the Field Bean Plants (Vicia faba L. minor) and Lack of the Pod Setting on the Symbiosis with Root Nodule Bacteria

The plants of field bean var. Nadwiślaνski were detopped after about 1 month since the beginning of flowering and after that all flower buds were removed from some plants. The effect of a change in the trophic balance on the setting and subsequent growth of root nodules was studied.
The removal of pods had the greater effect on the increase in the weight of the remaining organs than the detopping of plants. Detopping retarded the ageing of the plants and delayed the phase of the greatest reduction of the number of pods. The detopping of plants revealed their considerable compensative possibilities in terms of production of the pod weight and the potential of leaves for biomass production. The data obtained indicate that plant detopping may disturb the root–bacteria exchange of signals, necessary to initiate the nodule development, while the further growth of nodules depends, above all, on the amount of available photosynthates.
A very high correlation between the dry weight of the whole plant to the dry weight of leaves ratio and the weight of nodules was observed. It proves the importance of the trophic balance of the plant for the root nodule weight production.     

亚麻细菌病发生及防治技术研究

从亚麻细菌病的发生、发展、危害及病原茵特性到病害综合防治，进行了系统研究，明确了该病的发生与品种抗性、耕作栽培等诸方面的关系，为病害防治提供了理论依据；明确了种子带茵是该病害主要侵染源和传播途径，同时建立综合防病体系。     

一株克氏原螯虾病原——霍乱弧菌的分离鉴定

从尾扇边缘溃烂的克氏原螯虾中分离到一株优势菌LK-18,并对该菌株进行种属鉴定和致病性分析。通过菌落形态观察、16S rRNA测序、血清型分析及基因特性鉴定对细菌的类别进行初步判断,并采用浸泡感染、肌肉注射和腹腔注射等方式进行人工感染实验对细菌的致病性进行评估。经16S rRNA测序分析和4个管家基因（atpA、pyrH、recA、gyrB）串联分析,该菌株最终被鉴定并命名为Vibrio cholerae LK-18。V. cholerae LK-18经PCR鉴定不属于O1和O139血清型,但含hly毒力基因和几丁质分解相关的几丁质酶（chitinase,Chi）基因。人工感染实验虽未能重现烂尾症状,但从克氏原螯虾烂尾组织中分离的V. cholerae LK-18具有致病性,能够引起克氏原螯虾的死亡。研究结果表明霍乱弧菌LK-18是一种致病菌,不仅扩大了非O1/O139群霍乱弧菌的感染宿主范围,同时预警霍乱弧菌有导致克氏原螯虾养殖业暴发疾病的可能,因此要提前做好该疾病的预防工作,从而避免霍乱弧菌感染带来的损失。     

Continuous Production of Biogenic Magnetite Nanoparticles by the Marine Bacterium Magnetovibrio blakemorei Strain MV-1T with a Nitrous Oxide Injection Strategy

Magnetotactic bacteria (MTB) produce magnetosomes, which are membrane-embedded magnetic nanoparticles. Despite their technological applicability, the production of magnetite magnetosomes depends on the cultivation of MTB, which results in low yields. Thus, strategies for the large-scale cultivation of MTB need to be improved. Here, we describe a new approach for bioreactor cultivation of Magnetovibrio blakemorei strain MV-1^T. Firstly, a fed-batch with a supplementation of iron source and N₂O injection in 24-h pulses was established. After 120 h of cultivation, the production of magnetite reached 24.5 mg∙L⁻¹. The maximum productivity (16.8 mg∙L⁻¹∙day⁻¹) was reached between 48 and 72 h. However, the productivity and mean number of magnetosomes per cell decreased after 72 h. Therefore, continuous culture in the chemostat was established. In the continuous process, magnetite production and productivity were 27.1 mg∙L⁻¹ and 22.7 mg∙L⁻¹∙day⁻¹, respectively, at 120 h. This new approach prevented a decrease in magnetite production in comparison to the fed-batch strategy.     

土壤质地定名法及吸湿水与土壤粒级含量关系的研究

利用卡庆斯基制、美国制、中国制3种土粒分级标准对张家口葡萄产区的30个采样点进行土壤质地命名,并通过对比分析得出中国制是该区最适的土壤质地分类方法。现对吸湿水含量与土壤各粒级微粒百分含量的关系做了探测性研究,得出吸湿水和土壤中小于0.01 mm的粒径含量之间拟合曲线方程为:Y=20.272e0.207x,可根据此方程应用卡庆斯基制确定土壤质地;吸湿水和土壤中1~0.05 mm0、.05~0.002 mm粒径含量的拟合曲线方程分别为:y=22.018x2-105.323x+156.381,y=-18.304x2+86.495x-49.536,又可根据这2个方程利用美国制确定土壤质地名称。这些为用简易方法鉴定土壤质地类型提供科学依据。