Differences in common bean rhizobial populations associated with soil tillage management in southern Brazil

Progressive adoption of no-tillage (NT) agriculture in the tropics is finally reversing physical, chemical, and biological erosion of soil and in Brazil, an estimated 19 Mha are now devoted to NT. Common bean (Phaseolus vulgaris L.) is a main component of Brazilian agriculture, and enhancement of yields has been achieved under NT as a result of mitigation of environmental stresses, resulting in higher N₂ fixation. However, the effects of NT on rhizobial diversity are poorly understood. This study evaluated rhizobial diversity in soils planted to common bean under NT or conventional tillage (CT) systems that were compared with natural grassland used for grazing, in the State of Santa Catarina, southern Brazil. Genetic diversity was assessed by the amplification of the DNA by PCR with specific primers (BOX-PCR) and by RFLP-PCR analyses of the 16S rDNA region. A high level of diversity was observed among strains from all three systems, such that the similarity in the clustering analysis of BOX-PCR products ranged from 36% under natural grassland to only 23% for CT strains. High polymorphism was confirmed in the RFLP-PCR analysis; forty-seven different profiles were obtained, none sharing high similarity with the profiles of reference species of common bean rhizobia. These results indicate that other tropical rhizobial species remain to be described. Genetic diversity was higher among the NT than the CT rhizobial strains, especially when the RFLP-PCR profiles were considered. Genetic diversity in the natural grassland was lower than in the cropped systems, possibly due to absence of the host plant and stubble burning in winter. Average yields in the area under NT (e.g. common bean, approximately 1500 kg ha⁻¹) have been about 30% higher than under CT, therefore high rhizobial diversity may be a parameter indicative of superior soil quality.     

我国西北地区生态林业发展政策研究

结合我国西北地区林业政策失灵的案例 ,剖析了西北地区现行林业政策失灵的原因。并提出完善林业产权制度 ,建立森林生态效益补偿机制 ,以土地换生态 ,完善退耕还林的西北地区生态林业政策框架。     

从文化渔业的角度谈休闲渔业发展的新路径

休闲渔业是实现现代渔业转型发展的重要途径,然而我国雨后春笋般出现的休闲渔业产业如出一辙的模式使休闲渔业发展陷入瓶颈期,本文试图从“文化学”角度探讨,重新整合运用现有资源,尝试为休闲渔业的发展寻找新的突破口.     

麋鹿常见普通病例诊断与治疗

[目的]为麋鹿小种群管理工作中糜鹿普通病的防控提供借鉴.[方法]以江苏大丰麋鹿种群为例,在麋鹿引种扩群、野生麋鹿种群恢复过程中长角血蜱寄生虫病、瘤胃膨胀、营养性衰竭症、食毛症、难产等常见普通病病例进行了总结.[结果]在麋鹿小种群饲养管理过程中加强前期防控,对有效降低和避免麋鹿普通病的发生尤为重要.[结论]该研究对动物园等麋鹿小种群管理起到借鉴作用,也为麋鹿的健康养殖和保护提供基础资料.     

Effect of Seeding Rate on Seed and Hay Yield in Common Vetch (Vicia sativa L.)

The effects of six seeding rates (50-300 seeds m^−2:) on some morphological traits with hay and seed yield were evaluated in common vetch ( Vicia sativa L.) under fall and spring sowing conditions. The mutual correlations among yield and yield components were also determined.
The sowing seasons and seeding rates significantly affected hay and seed yield, and most of the yield components. Fall sowings resulted in significantly higher hay and seed yield than spring sowings at all seeding rates, and the highest seed and hay yield was achieved in densities of 250 and 300 seeds m⁻². In spring sowings there was a positive response in hay yield up to 250 seeds m⁻² while no further increase in seed yield at the seeding rates higher than 150 seeds m⁻². Average protein content of hay and seed was found to be higher in spring sown crops than fall. The highest protein yields of hay and seed were obtained at 250 seeds m⁻² in fall sowings, and 150 seeds m⁻² in spring sowings.
Most of the correlations between both hay and seed yields with the yield components were not consistent and differed with the sowing time. Only the correlations between number of the plants per unit area with hay yield, and number of the pods and seeds per unit area with seed yield were statistically significant in both sowing seasons. Close positive associations were obtained between hay and seed yield.     

菲律宾稻米标准与政策研究

菲律宾是世界主要进口大米国家之一,实现大米的自给是它的一项基本国策。菲律宾非常重视稻米质量标准的研究,对稻米的分级指标和分级方法进行了长期的有效的探索。菲律宾稻米分级系统参照了联合国粮农组织(FAO)推荐的大米分级模式,推行视觉识别标准化包装是菲律宾稻米质量标准的一个重要特征。菲律宾注重通过标准化计划的实施使得菲律宾稻米生产者、加工者、贸易商和消费者对谷物标准的实施增加感性认识,提高执行标准的自觉性的做法值得中国借鉴。     

贵州省退耕还林亟需解决的问题及政策建议

通过对当前贵州省退耕还林总体情况的摸底分析,提出下一步退耕还林政策建议。     

Precise, simple screening for resistance in potato varieties to common scab using paper pots

Resistance to common scab pathogen Streptomyces turgidiscabies of seven potato varieties was compared in the field with a newly developed paper pot method. Seedlings raised in soil in paper pots containing inocula at 1 × 10³ to 10⁷cfu/g soil were transplanted into a scab-free field and grown for 3 months. The disease severity of the seven varieties in the field trials differed in iteration and from year to year, even though their resistance levels were approximately similar at the expected levels. With the paper pot method, the seven varieties had different resistance levels, which were almost completely consistent with the results of the field trials, at more than 1 × 10⁵cfu/g soil. Significant differences in disease severity between resistant and susceptible varieties were observed (P = 0.05) for 2 years, and the resistance level of the varieties was elucidated.     

新时期政府调控蔬菜价格的政策选择

为构建菜价调控的长效机制,在蔬菜市场化水平不断提高的新背景下,从创新价格信息的形成和传递机制、打造稳定的流通链条以及政府蔬菜储备的合理布局和科学投放等3个方面提出了政府调控蔬菜价格的政策选择。     

应用荧光定量PCR 技术分析普通菜豆品种中尖镰孢菜豆专化型定殖量

尖镰孢菜豆专化型(Fusarium oxysporum f. sp. phaseoli)引起的菜豆枯萎病是菜豆生产中最严重的维管束类病害之一, 防治该病害有效方法是利用抗病品种。因此, 一种能够从菜豆受侵染组织中准确鉴定并定量检测枯萎病原菌含量的方法将有助于筛选抗性品种, 应用于普通菜豆枯萎病抗病育种。本研究基于荧光定量PCR技术开发出一种能够对定殖于菜豆组织中的枯萎病原菌准确定量的新方法。该技术对根、茎组织中病原菌DNA的最低检测量为1 pg, 能在接种病原菌6 d后明显区分抗病性不同的品种, 可在菜豆植株表现出明显发病症状前准确鉴定不同品种抗性水平的差异。经验证参试的感病品种BRB-130和A0640-1根、茎组织中定殖的病原菌DNA量显著高于抗病品种260205和黑芸豆, 与表型鉴定的结果完全符合。利用荧光定量PCR技术能够在病原菌侵染早期快速、准确、高效定量菜豆组织中定殖的病原菌, 这对指导菜豆抗病育种和植物病害传播的研究都具有非常重要价值。