利用EPS-98软件进行药剂毒力分析

利用 EPS- 98软件进行药剂毒力分析 ,具有快捷、方便、功能多 ,提示式问答输入、可检查纠错、结果输出方式多样、输出结果直观易懂等优点 ,可直接获取优化毒力回归式及相关系数、L D5 0及其标准误和置信限、LD95及其标准误等结果     

Amelioration of Aluminum Toxicity by Pretreatment with Phosphate in Aluminum‐Tolerant Rice Cultivar

Abstract

The phytotoxicity of aluminum (Al) in relation to preculture with phosphates was examined in the rice cultivar Arkansas fortuna. In plants precultured with phosphates, Al did not inhibit shoot growth, while Al retarded shoot growth in plants precultured without phosphates. In contrast, Al inhibited root elongation, irrespective of the presence of phosphates in the preculture solution. A large proportion of the Al in roots was in unknown, insoluble forms. In phosphate‐precultured plants, Al deposition was slightly increased, presumably due to the formation of aluminum phosphates in the roots, and phosphorus levels in shoots were markedly increased. Binding with phosphates may ameliorate the toxicity of Al when it enters the shoots and account for the uninhibited shoot growth in the presence of Al in plants precultured with phosphates.     

棉花药害的原因分析及对策

调查分析了棉花药害的症状和产生原因 ,提出了药害预防及补救措施 ,对保证棉花安全生产具有重要指导意义。     

特种稻种资源的利用及其系列产品的开发

这是一篇科研成果的综合报告，该项目发表系列研究论文１３篇，选育了特种稻品种２个，研制出３个黑系列产品，取得了较显著的经济与社会效益。     

Phosphorus and potassium depletion by roots of field-grown slash pine: Aerobic and hypoxic conditions

Slash pine (Pinus elliottii Engelm. var. elliottii) is planted extensively on flatwood and coastal savanna soils of the southeastern USA. Pine roots growing in these soils encounter shallow water tables. Although the fine-root system of pine trees growing in the surface 20–26 cm of those soils will not be continuously submerged, they will encounter short-term reduced soil conditions, with a severely reduced O₂ supply which might affect their ability for ion uptake from the soil solution. The objectives were: (i) to compare P and K depletion by lateral root systems of slash pine roots subjected to a short-term hypoxic treatment, and (ii) to document K and P depletion patterns by lateral root systems of slash pine roots following the removal of the hypoxic treatment. Our purpose was to evaluate the uptake ability of these roots of changing aeration. For the experiment, 17 intact lateral roots from twelve-year-old slash pine trees were inserted into nutrient-uptake root chambers. The chambers were filled with a nutrient solution containing 6.25 μM P (phosphate), and 25.66 μM K. P and K depletion rates were monitored in six consecutive treatments, each lasting five days. Treatments of aerobic and hypoxic conditions were sequentially applied in the following order: aerobic–hypoxic–aerobic. This sequence was repeated twice. Uptake of P and K by slash pine roots was affected by oxygen availability, but the degree of response differed. Under hypoxic nutrient solution conditions, K depletion from solution by pine roots was totally inhibited, resulting in net efflux of K. In contrast, P depletion was not inhibited under hypoxic nutrient solution conditions. Results suggest that pine roots grown in aerobic soil conditions of surface horizons are capable of P depletion when reduced soil conditions are present.     

Structure of silver fir (Abies alba Mill.) natural regeneration in the ‘Jata'' reserve in Poland

Over the last 20 years, investigations have been carried out to determine the influence of various ecological factors on silver fir natural regeneration in highlands and mountains. However, there has been little research on the structure and development of fir regeneration in lowlands. Results of this study indicate that three main stand characteristics play a very important part in the structure of fir regeneration in the lowland. The results revealed that the quantity, frequency and growth rate of fir regeneration were affected by site conditions. One of the most important ecological factors differentiating quantity and quality of fir regeneration was the proportion of fir in a stand. It was found that, with an increase in the percentage of fir in a stand, the quantity and the sum of heights and the sum of height increments of fir regeneration tends to increase. Results of this study showed that the number and development of fir regeneration were influenced by species composition of a stand; fir regenerated not only in pure fir stands but also in mixed forests. A positive influence of pine and birch canopy on initiation and development of fir regeneration was confirmed. Optimal conditions for the growth and development of fir with respect to species composition were found in mixed fir stands with an admixture of hornbeam. In contrast, results of the study suggest that the worst conditions for fir regeneration were found in the stands composed of species, such as ash, alder, oak, aspen, lime and spruce.     

Evaluation of Joint Toxicity of Enrofloxacin and Three Antimicrobials on MRC-5 Cells

The aim of this study was to evaluate the combined toxicity of enrofloxacin with each of three antimicrobials (ciprofloxacin,florfenicol and sulfamethazine).MRC-5 cells were used as a cell model to simulate the damage of lung cells caused by mixed contamination of antimicrobials.Multiple concentration gradients and mixing ratios were set.CCK-8 method was used to determine the inhibition rate of cell growth caused by four antimicrobials and the inhibition rate of cell growth caused by enofloxacin mixed with three antimicrobials,respectively.Then Chou-Talalay method was used to fit the median effect plot and to calculate the combination index (CI) value.The results showed that the growth inhibition rates of MCR-5 cells caused by four single drugs went up in a step-like manner with the increase of drug concentration in the tested concentration range,among them,the growth inhibitory rate of MCR-5 cells by florfenicol was low (<4.5%).The combined toxicity of the three binary combinations showed a concentration-dependent and mixing-ratio dependence.Mixing enrofloxacin and ciprofloxacin showed synergistic toxicity (CI<1) on MRC-5 cells at high and middle concentration groups,and antagonistic toxicity (CI>1) at the very-low-concentration groups.Mixing ciprofloxacin and florfenicol mainly showed an inhibited toxicity (CI>1).Binary combination enrofloxacin and sulfamethazine might present either a synergistic joint toxicity (CI<1) or an antagonistic joint toxicity (CI>1) as the concentration and mixing ratio changing.This study showed that it was necessary to assess the combined toxicity of antimicrobials in the toxicity evaluation of antimicrobials.Using Chou-Talalay method,the joint toxicity of multiple antimicrobials could be quickly and efficiently determined at cellular level.     

网络环境下专业图书馆工作的转变

本文论述了网络环境下专业图书馆转变业务工作的措施及需要注意的问题。     

Some nutrient dynamics associated with litterfall and litter decomposition in hoop pine plantations of southeast Queensland, Australia

Litterfall was collected over a 12-month period with littertraps in hoop pine (Araucaria cunninghamii) plantations aged 10, 14 and 62 years in southeast Queensland, Australia. The bulk of litterfall occurred during spring, mainly as hoop pine foliage with the annual litterfall ranging between 6.0 and 10.9 t ha⁻¹, respectively, for the younger stands (10 and 14 years) and the mature 62-year old stand. The amount of nitrogen (N) and phosphorous (P) recycled annually through litterfall was lower in the younger stands (28–37 kg N ha⁻¹ and 4.4–5.3 kg P ha⁻¹) compared with that of the mature stand (85 N ha⁻¹ and 6.2 kg P ha⁻¹). The N and P retranslocated during senescence varied across the three stands studied with a trend for N and P retranslocation to increase as availability of soil mineral-N decreased.

Decomposition of the hoop pine foliage component of litter was also studied in the same stands using a litterbag technique and mass-balance analysis. The estimated half-life of hoop pine foliage mass ranged between 1.5 and 1.8 years. Litter-mass loss was strongly correlated with litter substrate quality indicators of N, C, P, C/N ratio, lignin, lignin/N ratio and polyphenols. During the course of the study, there was no difference in litter-mass loss between the stands of different ages. During the 15-month period, the order of element release from the hoop pine litter was K>Na>C>Mg>P, with N, Ca and Mn generally demonstrating varying degrees of net accumulation. During the course of the study, the lignin/C ratio of the hoop pine litter increased from 0.61 to 0.96. This suggested that the litter-C was predominantly in a recalcitrant form and, therefore, the associated N was unlikely to be rapidly released in the hoop pine litter layer.