Banishing barberry: The history of Berberis vulgaris prevalence and wheat stem rust incidence across Britain

Wheat stem rust, caused by the fungus Puccinia graminis f. sp. tritici (Pgt), is a notoriously damaging disease of wheat and barley. Pgt requires two hosts to complete its lifecycle; undergoing asexual reproduction on cereal crops and completing sexual reproduction on Berberis spp. The latter stage of its lifecycle is of particular importance in temperate regions such as western Europe, where asexual urediniospores are unable to survive cold winter weather. In the past, the crucial role of Berberis in the lifecycle of stem rust led to intensive eradication campaigns, initially carried out by farmers in the face of hostile scientific opinion. In the United Kingdom, common barberry (Berberis vulgaris) is today a relatively rare plant. Stem rust is, however, currently experiencing a resurgence; at the same time, there has been a general increase in the prevalence of barberry and an upsurge in its planting which, in the United Kingdom, is associated with attempts to encourage the endangered barberry carpet moth (Pareulype berberata). This article situates current developments within a broader chronological framework, examining changing attitudes towards barberry and rust in England in the past and the history of the plant's use and cultivation. It assesses how widespread B. vulgaris really was in the environment historically, and thus the scale of its eradication. We suggest that Berberis was never widely established as an archaeophyte in the United Kingdom. Current attempts to re-establish it are based on a misunderstanding of the plant's historical status and could potentially pose a serious threat to food security.     

“一带一路”沿线分区用水结构与产业结构的分析比较

“一带一路”沿线用水结构与产业结构的分析,对支撑沿线区域发展意义重大。基于“一带一路”主体水资源区分区及用水研究,采用赫芬达尔-赫希曼指数（HHI指数）分析了“一带一路”产业用水量和GDP的地理集中度,采取用水结构指数和产业结构指数分析了分区用水结构及产业结构的差异,应用洛伦茨曲线和基尼系数对“一带一路”全区用水量与GDP的匹配度进行研究,计算了“一带一路”分区基于数列的用水量与GDP匹配度。结果表明：① “一带一路”第一产业用水量和GDP产值的集中度在三大产业中均为最高,主要集中在东亚、西亚、南亚和东南亚;② 不同分区分产业用水量和GDP产值占各分区总量的比值,在空间分布差异上从大到小依次为第一、第三、第二产业;③ “一带一路”全区第三产业用水结构与GDP产值匹配度最差,南亚是第一产业和第三产业匹配度最差的分区。分析成果有助于系统了解“一带一路”区域用水和产业结构的基本情况,为深入分析分区水资源与经济社会关系提供指导。     

Initiation and development of microspore embryogenesis in recalcitrant purple flowering stalk (Brassica campestris ssp. chinensis var. purpurea Hort.) genotypes

Purple flowering stalk (Brassica campestris ssp. chinensis var.purpurea Hort.) was generally regarded as a recalcitrant species for microspore culture in Brassica crops. Conditions for reliable induction of microspore embryogenesis were studied in 12 genotypes of purple flowering stalk. A treatment of short heat shock to microspore by incubating at 32 °C for 18 h was suitable for the survival of microspores, sustained cell divisions, and further induced embryogenesis. Subsequently, the reduced concentration of macro salts (1/2 NLN) provided an optimal condition for the development of embryoids. Under the optimized conditions for microspore embryoid development, 10 genotypes responded to microspore culture with the frequencies ranging from 2.7 to 70.5 embryoids per dish. However, regenerated plants were obtained from 9 genotypes, and more than 75% these regenerated plants were double haploid. This report establishes an efficient protocol for microspore culture and offers great potential for DH breeding in purple flowering stalk.     

有机酸对甘薯紫色素热稳定性与抗氧化性的影响

甘薯紫色素在酸性条件下呈稳定的红色,可作为天然红色素.优化了甘薯紫色素提取条件,研究4种有机酸不同浓度对甘薯紫色素热稳定性及抗氧化性的影响.结果表明,苯甲酸、乙酸和乙二酸可显著提高甘薯紫色素的热稳定性,程度依不同浓度而异,而抗坏血酸则显著降低其热稳定性.苯甲酸、乙酸、乙二酸和抗坏血酸可以显著提高甘薯紫色素加热后的抗氧化性,程度依不同浓度而异.     

紫色丘陵区坡耕地生物埂土壤抗冲性研究

本文以紫色丘陵区坡耕地4种典型生物埂为研究对象,采用原状土冲刷水槽法系统分析各种生物埂的土壤抗冲性。结果表明:（1）各种生物埂径流含沙量随着冲刷时间的继续出现“先急剧减小后平稳减小直至稳定”的变化趋势。在冲刷0~3 min,各生物埂土壤的径流含沙量均较大,随后径流含沙量平稳变化并趋于稳定。（2）生物埂抗冲刷过程可划分为快速冲刷阶段（0~3 min）、慢速冲刷阶段（3~20 min）和平稳冲刷阶段（20~28 min）3个阶段。生物埂土壤抗冲性随着冲刷时间的增长而不断增强,两者之间可用幂函数表示,其R²值在0.848 7~0.989 9。（3）各种生物埂土壤抗冲性随着坡度的增大而降低,两者关系达到极显著水平（R²=0.790 7,N=12,p < 0.001）,可用幂函数表示。研究结果可为紫色丘陵区坡耕地生物埂措施合理布置及其稳定性评价提供科学依据。     

Assessing the Success of “Cocoa na Chocolate” Musical Intervention in Mobilizing the Youth for Agriculture in Oyo State,Southwestern Nigeria

The study assessed the success of “Cocoa na Chocolate” musical intervention for agricultural mobilization in Oyo State, Nigeria. Responses from 160 randomly selected students on awareness, exposure, retention, perception, and constraints to utilizing its message using structured questionnaires were analyzed. Most respondents (88.8%) had contact with the album, many (55.6%) were aware of its agricultural content, heard it six times, and most (76.1%) retained the contents. More (54.9%) had an unfavorable perception of its mobilization potential, and were constrained to utilize its message by credit facilities (M = 1.0938). Workable agricultural credit schemes are needed to complement future mobilization efforts.     

不同类型耕地紫色土中3,5,6-三氯-2-吡啶醇迁移试验与模拟

3,5,6-三氯-2-吡啶醇(TCP)的化学结构稳定、水溶性高、运移能力强,对水体具有潜在的污染风险。在有机质含量低、大孔隙度高、导水性好的紫色土地区,风险更加显著。为研究TCP在紫色中的迁移规律,该研究依据紫色土的典型耕作类型,在中国科学院盐亭国家紫色土农业生态试验站采集3组土样(小麦-玉米轮作的坡地、水稻-油菜轮作的水旱农田和萝卜-白菜套种的菜地),通过批量平衡法研究紫色土对TCP的吸附特征,并采用稳定流场饱和均质土柱的易混合置换试验研究TCP的动态迁移过程,最后对其迁移动态进行模拟。结果表明:紫色土对TCP的吸附特征呈线性,在坡地、水旱农田和菜地中的吸附系数分别为1.94、1.22和1.02 L/kg,且黏土含量和矿物组成是主要影响因子;TCP的出流平衡浓度分别为初始浓度的77%(坡地)、84%(水旱农田)和92%(菜地),相应的平衡时刻分别为2.88PV、4PV和6.5PV,表明TCP对环境的污染风险较高;用非平衡两点对流弥散模型模拟TCP在3种耕作条件下迁移,表明TCP以瞬时吸附为主,其水动力弥散系数和分形系数在坡地、水旱农田和菜地中依次减小,但一阶动力学常数依次增大。研究结果为探索TCP在紫色土壤中的迁移机制和预测防止TCP对环境的污染提供了参考依据。     

紫色土坡耕地氮素淋失通量的实测与模拟

氮淋失是氮素循环研究中最重要的环节之一,获得准确的氮淋失通量是当今农田氮循环研究中必不可少而又较为困难的工作之一。紫色土土层薄,土壤氮素难以蓄存,加之降水丰富,下伏透水性较弱的母岩,淋溶水达到母岩后难以垂直下渗而沿土壤岩石界面出流、汇流形成壤中流,紫色土氮素淋失主要表现为氮素随壤中流迁移流失。DNDC模型是基于过程的一种土壤碳氮循环模型,常用于农田温室气体排放模拟,但其应用于氮素淋溶的验证与测试不足。本文利用大型坡地排水采集器(lysimeter),测定紫色土坡耕地淋溶水量(壤中流流量)和氮素淋失通量,并利用观测数据对DNDC模型进行验证。结果表明,紫色土坡耕地小麦玉米季累积淋溶水通量为323.6 mm,径流系数33.3%,氮素淋失量为36.93 kg.hm 2,占全年氮素施用量的13.2%。壤中流流量与氮素淋失量实测值和模拟值的Pearson相关系数分别为0.944(P<0.05)和0.972(P<0.05),Theil不等系数分别为0.07和0.1,降雨量、土壤孔隙率和施氮水平是氮流失模拟的高敏感性参数。DNDC模型应用于紫色土坡耕地氮素淋失通量的模拟具有较高的可靠性,同时DNDC基于过程模型的优势可以描述持续降雨条件下的氮淋失过程,未来可通过进一步的验证,测试DNDC模型应用于氮淋失过程及区域氮淋失评估的可行性。     

横坡和顺坡耕作对紫色土土壤团聚体稳定性的影响

通过径流小区试验,分析探讨了紫色土横坡和顺坡两种耕作模式下表层(0~20 cm)土壤水稳性团聚体及有机碳含量的特征,为紫色土区坡耕地的有效改造和综合利用提供科学依据。试验结果表明,横坡耕作下土壤水稳性指数K值比顺坡耕作高38.99%,而土壤分散性D值为顺坡耕作的1.64倍,横坡耕作抗蚀性大于顺坡耕作。横坡耕作>0.25 mm水稳性团聚体含量比顺坡耕作增加3.62%,>5 mm、5~3 mm、3~2 mm水稳性团聚体含量横坡耕作均高于顺坡耕作,横坡耕作显著提高>2 mm水稳性团聚体含量。横坡耕作下团聚体结构体破坏率较顺坡耕作减少3.05%,团聚体平均重量直径为顺坡耕作的1.39倍。2种耕作模式下0.5~2 mm团聚体有机碳含量均最高,>0.25 mm不同粒级团聚体有机碳含量百分数均随粒径的减小而减小,均在0.5~0.25 mm粒级下达到最小。横坡和顺坡耕作模式下2~1 mm团聚体有机碳含量无显著差异。横坡耕作较顺坡耕作能够显著增加紫色土>2 mm水稳性团聚体含量,且对有机碳的固持作用更好,有利于土壤结构的改善。     

垄作免耕下紫色水稻土有机碳的分布特征

土壤有机碳的空间分布特征是研究土壤有机碳储量及其动态的重要内容之一。本文从土壤团聚体、剖面和田块等尺度研究了四川盆地紫色水稻土在垄作免耕下有机碳的分布特征。结果表明：紫色水稻土团聚体含碳量在大团聚体（2～0．25mm）中最高，但有机碳总量主要分布在0．25～0．02mm。其次是0．02-0．002mm；垄作免耕下团聚体有机碳主要富集在0—10cm土层的大团聚体（〉0．25mm）中（富集系数〉1．5），而常规平作、水旱轮作和垄作翻耕下，剖面中土壤有机碳含量分布自上而下缓慢降低；实验田表层土壤有机碳含量及相关土壤特性的空间分布呈条带状和斑块状格局，具有明显的空间变异性。土壤有机碳含量在垄作免耕处最高，达30．71g kg^-1，在常规平作处最低，为16．50g kg^-1左右。长期垄作免耕会导致有机碳向土壤表层大团聚体的相对富集及在土壤剖面的层次分异。