西双版纳社区旱稻品种多样性现状调查报告——以巴卡小寨、大卡老寨和曼那龙寨为例

本文应用户级水平的农业生物多样性评价方法 ,在 2个热带山地村寨 (大卡老寨、巴卡小寨 )和一个热带坝区村寨 (曼那龙寨 )按 39%的比例随机抽取农户 ,利用半结构访谈 ,问卷调查等方法进行旱稻种植情况以及社会经济状况调查 ,并对传统旱稻品种进行收集和鉴定。结果表明 :在 3个村寨中 ,旱稻品种存在丰富的形态多样性和遗传多样性 ;一些需肥 ,优质的旱稻品种已经或濒于消失 ,而耐瘠 ,米质差的旱稻品种占绝对优势 ,旱稻品种趋于单一化 ;农户保存的旱稻品种数及类型不仅受旱稻种植面积、轮歇地面积的影响 ,还受各农户饮食习惯、种植技术、市场需要、以及民族文化的影响。因此 ,必须采取多种措施对旱稻品种多样性进行保护     

中国云南元阳哈尼梯田种植的稻作品种多样性

稻作是我国第一大粮食作物,近年来,选育品种的大面积单一化种植,导致种植的稻作品种遗传基础狭窄,多样性下降,已经受到关注。然而在一些少数民族地区,如元阳哈尼梯田,当地民族的传统文化习俗已经保护了当地的水稻资源,高度的多样性依然存在。采用半问卷式和农村参与式评价方法(PRA),在村寨和农户两个水平,调查分析中国云南省元阳哈尼梯田种植的稻作品种多样性,尤其是当前仍在种植的传统品种的多样性,为稻作传统品种多样性农家就地保护提供典型范例。结果表明,在调查的30个村寨750户中,共种植135个具不同名称的水稻品种(组合),包括100个传统品种,12个杂交稻组合和23个现代育成品种;种植传统品种的面积占总稻作面积的56.2%;平均每个村寨种植9.7个品种,最多的达19个,最少仅4个;每个村寨至少种植2个传统品种和1个现代品种;种植最多的是传统品种"老粳糯",有12个不同村寨种植;大多数传统品种仅有12个不同村寨种植。有11个村寨(占的30个村寨36.7%)的所有农户均种植传统品种。在农户级水平上,有611户(占81.5%)种植传统品种;有391户(占52.1%)同时种植传统品种和现代品种,其种植传统品种与现代品种的面积比例平均为1/2;仅种植传统品种的有220户(占29.3%)。平均每户种植2.2个品种(组合),最多的农户种植5个品种,包括3个传统品种,1个现代常规品种,1个杂交稻组合。传统品种的丰富度,村寨平均为5.9,最高达12,而农户平均为1.541;传统品种的均匀度,村寨平均为0.670,农户平均为0.192;不同村寨种植传统品种的差异度平均值为0.702。其中太阳老寨、新寨村、欧乐、多沙和上马点等5个村寨传统品种的丰富度与均匀度均较高,在稻作传统品种农家保护中扮演着重要角色。在村寨和农户水平,传统品种丰富度与均匀度的相关性均呈极显著正相关(r=0.627,0.925);村寨传统品种丰富度与农户数呈极显著正相关(r=0.473);村寨农户年人均纯收入分别与村寨传统品种丰富度和农户数呈极显著和显著负相关(r=-0.570,-0.370*)。在如此小的耕地面积(142.29hm2)上,当前生产上仍种植着如此丰富的稻作传统品种,实属少见。高度异质的生态环境和民族文化习俗是哈尼梯田传统稻作品种多样性种植的重要因素,建议将元阳哈尼梯田作为稻作传统品种多样性农家就地保护区。     

热带地区农户薪炭林户级水平农业生物多样性评价——以西双版纳大卡老寨为例

在西双版纳大卡老寨通过随机抽样和农户推荐选择 8户农民 ,对其薪炭林采用典型取样法设立 8个样方进行调查并结合全村 6 0 %抽样比例的半结构访谈、问卷调查等方法进行社会经济状况调查。结果表明 :不同农户之间薪炭林物种丰富度和农业物种丰富度指数差异较大。不同农户的薪炭林因植物种类和数量的不同 ,导致不同农户薪炭林之间植物群落相似性系数较小 ,不同农户薪炭林植物资源具有的经济效益各不相同。从而说明不同农户在保存物种丰富度和发展农业物种丰富度的同时 ,获得的经济效益存在差距。采用曲线S =a blnB作为农户数 -物种数曲线的拟合模型初步确定一个村寨薪炭林户级水平农业生物多样性的抽样比例为 1 5 %。文末附大卡老寨农户薪炭林户级水平植物编目 ,包括当地名、拉丁名、中文名、利用部分和用途等     

西双版纳傣族村寨对湿地植物的传统利用

作者用半结构访谈与关键人物访谈相结合,并佐以证据标本采集的民族植物学研究方法,对云南省西双版纳3个自然环境和经济社会条件差异较大的典型傣族村寨(曼降,曼安,曼伞)居民的湿地植物知识,以及不同性别、年龄人群掌握湿地植物知识的差异作了统计分析。研究结果表明:(1)西双版纳傣族村寨利用的湿地植物种类丰富,经鉴定的有46科102种,以湿生植物为主;利用类型有食用类、药用、代茶类和宗教类等,以食用类为主。(2)三个村寨中以曼伞调查和采集到的植物种类最多,曼安次之,曼降最低。3个村寨利用的湿地植物种类的相似性低。这与村寨周围的自然植被类型及其干扰程度密切相关。(3)统计分析显示,村寨的自然环境与经济发展状况对该村村民传统湿地知识的掌握有重要的影响。食用和药用、代茶植物知识在3个村寨都表现为年长组(>45岁)明显高于年轻组(≤45岁,P<0.05),而男性和女性对不同知识的掌握则因村寨自然环境和经济发展状况的不同而各不相同。植物多样性和民族传统文化多样性的关系显示出传统知识的传承对植物多样性保护是十分重要的。     

甘、青两省春小麦遗传多样性演变

对甘、青两省自20世纪40年代以来生产上曾大面积应用的200多个春小麦地方品种和育成品种资料进行了分析,结果表明,19个形态性状,5个农艺性状和2个品质性状都存在着广泛的遗传多样性,虽然育成品种农艺性状和品质性状的遗传多样性总体上大于地方品种,但是从20世纪60年代开展春小麦杂交育种工作之后,育成品种形态性状,农艺性状和品质性状遗传多样性呈下降趋势,评价育种对小麦遗传多样性的影响,不能足将地方品种和育成品种的遗传多样性作一简单比较就得出结论,而是应该在遗传多样性演变的动态过程中去研究。     

贵州稻种资源遗传多样性研究现状与展望

贵州稻种资源遗传多样性的研究与利用已取得较大进展。主要表现在：(1)收集整理了地方稻种5168份并入国家种质库长期保存,系统完成其农艺性状和特性的鉴定与评价,筛选出一批矮秆、大穗、大粒、优质、特种稻、抗病虫、抗衰以及耐冷、抗旱性突出的优异种质;(2)研究表明,品种多样性是环境对品种的选择和品种对环境的适应双向作用的环境同化产物,在贵州高原低温高湿寡照生境下形成禾类和旱稻等种质资源;(3)开展了地方稻种中细胞质雄性不育恢复源、非sd-1基因新矮源、广亲和、双(多)胚等特性有利基因资源的鉴定和筛选;(4)明确了收集品种的类型及其保存途径,建立以基础样品、活动样品和核心样品的分类数据库为基础的资源信息管理系统。对推动研究工作的深入发展等问题展开了讨论。     

云南15个特有少数民族当前农家保护的稻、麦、玉米地方品种多样性

相对于种质资源的异位保护,作物地方品种的农家保护和利用作为植物种质资源保护方法被提出,但是,关于这种方法的有效性却知之甚少。文章采用问卷式和农村参与式调查评价方法(PRA),通过对云南省15个特有少数民族分布的11个州(市)、36个县、124乡(镇)、237个行政村中的306个村寨(村小组),针对当前农家保护的稻、麦(包括小麦、大麦、燕麦和黑麦)和玉米地方品种多样性进行实地调查分析,结果发现已有44.8%的村寨稻地方品种丢失,77.5%的村寨麦地方品种丢失,37.3%的村寨玉米地方品种丢失。共调查采集到农家保护的地方品种901个,其中稻、麦和玉米分别为371、119和411个。每个村寨均有农家保护的地方品种(平均为2.9个),平均每100户农户、1 000人和100 Ha耕地面积分别有3.3个、8.0个和5.2个地方品种。其中,尤以西盟县勐梭镇里拉村委会老缅小组有18个地方品种(包括10个稻和8个玉米),元阳县新街镇土戈寨村委会箐口村有14个稻地方品种最为突出,实属少见。同时,各民族农家保护的地方品种多样性存在显著差异,变幅为16～120个,其中,稻在各民族中的分布变幅最大,为1～72个,主要分布于滇南、滇西南热带、亚热带民族地区;麦变幅次之,为0～47个,主要分布于滇西、滇西北高海拔、温凉民族地区,且在傣族、基诺族和阿昌族等3个民族中已丢失;玉米变幅最小,为4～40个,最均匀。总之,各民族农家保护地方品种的主要驱动力是满足该民族传统文化习俗的生活需求,以及由于缺乏适宜当地特殊生境的新品种以满足生产需求。因此,云南特有少数民族地区是开展农家保护研究的理想基地,建议在该区域选择一定村寨建立地方品种农家保护示范区,同时加强对当前农家保护的地方品种的高效利用研究。     

河北省大豆地方品种遗传基础

以50份河北省大豆地方品种为材料,通过两年对12个农艺性状鉴定和30个SSR位点的分析,结果表明,地方品种农艺性状平均多样性指数PIC为0.83,数量性状平均变异系数为20.15%,30个SSR位点平均等位变异数5.03,平均多样性指数PIC为0.61,参试材料遗传距离平均0.869。利用Bayesian模型将参试材料分为4组。分析结果表明,河北省地方品种的遗传多样性与地理来源或不同熟期类型间没有显著相关。     

国内部分玉米地方品种的品质与农艺性状的表型多样性分析

以710份玉米地方品种为材料,采用随机区组设计,研究了其在脂肪、蛋白质与淀粉等品质性状以及株高、穗长等农艺性状上的表型多样性,分析了这些研究材料的表型多样性在地理来源上的分布.结果表明:(1)平均油分含量4.92%,达到高油3、2和1等级的材料各11、2和3份,地区间差异不显著;(2)平均蛋白质含量12.55%,96%的材料达到食用玉米1等级蛋白质舍量,地区间差异显著;(3)平均淀粉含量70.88%,所有材料均未达高淀粉玉米品种审定标准;(4)株高、穗位高和雄穗分枝数等3个植株性状的变异程度大,地区间差异显著,华南、西南和西北的植株高大,雄穗发达,而华北和东北的植株矮小,雄穗分枝数较少;(5)在3个果穗性状中,变异程度大小依次是穗长、穗行数和穗粗,地区间差异显著,筛选到长穗、粗穗和多穗行材料各5、1和3份;(6)不同地区和不同性状的多样性指数均有显著差异,以华南、华东和西南玉米材料的多样性水平较高.所有研究材料的表型多样性分析结果显示这些材料的脂肪与蛋白质含量较高,淀粉舍量较低;华南、华东和西南种质的多样性水平明显高于其他地区的种质.     

河北省大豆地方品种遗传基础

以50份河北省大豆地方品种为材料,通过两年对12个农艺性状鉴定和30个SSR位点的分析,结果表明,地方品种农艺性状平均多样性指数为0．83,数量性状平均变异系数为20．15％,30个SSR位点平均等位变异数5．03,平均多样性指数为0．61,参试材料遗传距离平均0．869。利用Bayesian模型将参试材料分为4组。分析结果表明,河北省地方品种的遗传多样性与地理来源或不同熟期类型间没有显著相关。     

Household Differentiation and On-farm Conservation of Biodiversity by Indigenous Households in Xishuangbanna, China

With diversification of field type among households in same eco-environment and social situation, even in the same ecosystem, merging household socio-economics with biodiversity initiative values to determine incentives and optimum strategy of on-farm conservation of biodiversity. Botany survey of agroecosystems at landscape level in Daka and Baka, Xishuangbanna, Yunnan, China, as well as household differentiation of biodiversity in agroecosystem and on-farm conservation strategy merging household socio-economic characters were studied. There were 73 families 179 species distributed in 0.1 ha of different agroecosystems in Daka, and 70 families 166 species distributed in 0.08 ha different agroecosystems of Baka respectively. The cosmopolitan families, such as Gramineae and Compositae decreased the percentage of tropical families and subtropical families. Botany survey among 12 random selected households from Daka in 46 sampling plots of different agroecosystems showed significant differentiation of the species richness indices of natural biodiversity and agrobiodiversity as there were differences of cognition and utilization of plant species besides management practices among households. Dengrogram using the Ward method of hierarchical cluster analysis based on annual questionnaire interview of 60% household from 1998 to 2001 in Daka showed disparity among different households’ socio-economics which underpins management diversity. There were significant correlation coefficients between household socio-economics and species richness indices of different agroecosystems. Fallow size had significant positive correlation coefficients with species richness index of rubber plantation. By contraries, production input had negative correlation coefficients with species richness index of upland rice field. Meanwhile, cereal crop income had significant positive correlation coefficient with agro-species richness index of rubber plantation. By contraries, other income such as off-farm income had negative correlation coefficients with agro-species richness index of rubber plantation. Innovations of the expert farmer on agrobiodiversity on farm conservation were admiration.     

Status and factors influencing on-farm conservation of Kam Sweet Rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) genetic resources in southeast Guizhou Province,China

Background

Kam Sweet Rice (KSR) is a special kind of rice landrace that has been cultivated for thousands of years in the borders of Guizhou, Hunan, and Guangxi Provinces of China, and is mainly distributed in southeast Guizhou Province of China currently. KSR has many unique qualities, including strong resistance to diseases, pests, and adverse abiotic conditions, difficulty of threshing, and well glutinous features. KSR germplasm resources are an indispensable material and cultural symbol in the production and daily life and customs of the Dong people. Related studies showed that numerous traditional KSR varieties and cultivation area of KSR decreased sharply from the Qing dynasty to 2015, but many KSR varieties are still conserved in Dong villages of southeast Guizhou Province compared to other areas. However, the number of KSR varieties that are conserved on farms in southeast Guizhou Province and factors influencing the erosion and conservation of KSR genetic resources is unclear. Therefore, this study was an on-farm conservation investigation of KSR genetic resource in China’s major KSR producing areas—Liping, Congjiang, and Rongjiang counties in Guizhou Province and influencing factors analysis of KSR abandonment and conservation.

Methods

The information of KSR conservation status and variety characteristics, typical villages, Dong’s cultural customs, and factors influencing KSR abandonment and conservation was obtained using ethno-biology methods, mainly through field research interviews, including participatory observation, semi-structured interviews, key informant interviews, focus group discussions, and cultural anthropology. The altitude, plant height, awn color and length, hull color, and rice color of 156 KSR accessions in 28 villages were recorded. The variety quantity and cultivation area of KSR were investigated in 33 ethnic villages. Questionnaire surveys were conducted in typical Dong villages to obtain local farmers’ attitudes toward cultivation and protection of KSR. We randomly selected 26 farmers from Sizhai village and 30 farmers from Huanggang village and chose 3 social characteristics including age, gender, and education levels of farmers, and adopted the method of face-to-face interviewing to complete the questionnaires. Then, we analyzed the correlation and determined the significance between farmers with different social characteristics and farmers’ attitudes to KSR development and protection using SPSS 17.0 software.

Results

(1) On-farm conservation status of KSR: a total of 156 KSR varieties were collected from 28 ethnic minority villages from 13 townships (accounting for 21% of three counties) in Liping, Congjiang, and Rongjiang counties. KSR accessions accounted for more than 90% of local rice varieties in each village. According to local farmers, although the quantity of KSR varieties decreased more than 50% in the investigated villages compared to the past 10–20 years, some Dong villages have still cultivated KSR, accounting for more than 50% of the rice field area in 10 villages. This result showed that many KSR varieties are still conserved by in Dong villages, and these KSR varieties have a high genetic diversity of phenotypes. (2) Typical villages investigation: the cultivation area of KSR in Congjiang was the highest, 6.7 times larger than Liping and eight times larger than Rongjiang. In addition, the cultivation area of KSR in Dong villages was larger than that in other ethnic villages, and villages that had a higher planting area of KSR had more KSR accessions. (3) Farmers’ attitude toward the development and conservation of KSR: Dong farmers hold the negative attitudes concerning the development of KSR resources, but they thought it is necessary to protect KSR landraces. Especially, a high level of education and female, young, and old farmers played more important roles in the cultivation and protection of KSR.

Conclusions

Until now, some Dong ethnic villages have still cultivated KSR for thousands of years in Qiandongnan area, although the number of varieties and the planting area of KSR have been greatly reduced. In addition, ethnic traditional culture and social customs were the main influencing factors of KSR conservation; economic, management, and policy factors were the main influencing factors of KSR abandonment. Through the analysis of the correlation between farmers with different social characteristics and their attitudes toward the cultivation, reasons for conservation and abandonment, development tendency, and protection of KSR, we found that a high level of education and female, young, and old farmers play more important role in the cultivation and protection of KSR. Therefore, in order to promote the protection and sustainable utilization of KSR, it is necessary to build on-farm conservation of KSR and improve the position of female farmers and the education level of young people, and encourage the old people to educate the middle-aged to conserve and protect KSR as well as Dong’s traditional culture and social customs. This study is of great significance to promote better protection and optimal utilization of KSR and enable the public, government, and related researchers pay more attention to conserving ethnic traditional cultures.

     

Mechanisms Explaining Variety Naming by Farmers and Name Consistency of Rice Varieties in The Gambia

Mechanisms Explaining Variety Naming by Farmers and Name Consistency of Rice Varieties in The Gambia. Understanding variety naming by farmers is important for better understanding crop genetic diversity in farmer fields and its management by farmers. This paper describes variety naming of rice by farmers in The Gambia and presents mechanisms that explain naming diversity and consistency. Three types of variety names can be distinguished, referring to common old varieties, common new varieties, and uncommon varieties. Interview and plant data suggest that variety exchange affects variety naming within villages. As a result, variety names give information on the period of time a variety is used in a village, and on the flow of varieties between and within villages. Name consistency within and between villages results from and illuminates the dynamics of variety exchange within and between villages.     

SSR标记揭示的云南地方稻品种遗传多样性及其保育意义

为了探索水稻(Oryza sativa L.)地方品种的遗传多样性及其有效保育方法,对采自云南省17个村寨的82个水稻地方品种和3个国际常用的典型籼稻和粳稻品种进行了微卫星(SSR)分子标记的分析.利用19对SSR引物在85个水稻品种中共扩增出了83个基因型,其分子量变异在100～500 bp之间.基于各品种SSR基因型遗传相似系数聚类分析而获得的UPGMA树状图表明各水稻品种之间存在较大的遗传多样性,其相似系数变异在0.15～0.90之间.但这些地方品种的遗传多样性并非呈均等的地理分布.这85个水稻品种在相似系数为0.52之处分为二组,其中一组包括几乎所有的籼稻品种,而另一组包括全部的粳稻品种,表明SSR标记能很好揭示水稻籼-粳分化.同时,有些来自不同采集地的同名品种表现出一定的遗传差异,说明同名异物的现象存在.云南水稻地方品种具有丰富的遗传多样性,对其有效保育十分重要和迫切,但只有根据遗传多样性的水平和分布特点,采用正确的保育对策和取样方法才能确保对云南水稻地方品种的有效保育.结果进一步表明,选用适当的微卫星引物,可以为准确鉴定籼稻和粳稻品种及研究其进化规律提供有效的分子标记方法,并有利于有目标的水稻遗传资源保育和育种创新.     

SSR标记揭示的云南地方稻品种遗传多样性及其保育意义

为了探索水稻(Oryza　sativa　L.)地方品种的遗传多样性及其有效保育方法,对采自云南省17个村寨的82个水稻地方品种和3个国际常用的典型籼稻和粳稻品种进行了微卫星(SSR)分子标记的分析。利用19对SSR引物在85个水稻品种中共扩增出了83个基因型,其分子量变异在100～500　bp之间。基于各品种SSR基因型遗传相似系数聚类分析而获得的UPGMA树状图表明各水稻品种之间存在较大的遗传多样性,其相似系数变异在0.15～0.90之间。但这些地方品种的遗传多样性并非呈均等的地理分布。这85个水稻品种在相似系数为0.52之处分为二组,其中一组包括几乎所有的籼稻品种,而另一组包括全部的粳稻品种,表明SSR标记能很好揭示水稻籼-粳分化。同时,有些来自不同采集地的同名品种表现出一定的遗传差异,说明同名异物的现象存在。云南水稻地方品种具有丰富的遗传多样性,对其有效保育十分重要和迫切,　但只有根据遗传多样性的水平和分布特点,采用正确的保育对策和取样方法才能确保对云南水稻地方品种的有效保育。结果进一步表明,选用适当的微卫星引物,可以为准确鉴定籼稻和粳稻品种及研究其进化规律提供有效的分子标记方法,并有利于有目标的水稻遗传资源保育和育种创新。     

Influence of ethnic traditional cultures on genetic diversity of rice landraces under on-farm conservation in southwest China

Background

Crop genetic resources are important components of biodiversity. However, with the large-scale promotion of mono-cropping, genetic diversity has largely been lost. Ex-situ conservation approaches were widely used to protect traditional crop varieties worldwide. However, this method fails to maintain the dynamic evolutionary processes of crop genetic resources in their original habitats, leading to genetic diversity reduction and even loss of the capacity of resistance to new diseases and pests. Therefore, on-farm conservation has been considered a crucial complement to ex-situ conservation. This study aimed at clarifying the genetic diversity differences between ex-situ conservation and on-farm conservation and to exploring the influence of traditional cultures on genetic diversity of rice landraces under on-farm conservation.

Methods

The conservation status of rice landrace varieties, including Indica and Japonica, non-glutinous rice (Oryza sativa) and glutinous rice (Oryza sativa var. glutinosa Matsum), was obtained through ethno-biology investigation method in 12 villages of ethnic groups from Guizhou, Yunnan and Guangxi provinces of China. The genetic diversity between 24 pairs of the same rice landraces from different times were compared using simple sequence repeat (SSR) molecular markers technology. The landrace paris studied were collected in 1980 and maintained ex-situ, while 2014 samples were collected on-farm in southwest of China.

Results

The results showed that many varieties of rice landraces have been preserved on-farm by local farmers for hundreds or thousands of years. The number of alleles (Na), effective number of alleles (Ne), Nei genetic diversity index (He) and Shannon information index (I) of rice landraces were significantly higher by 12.3–30.4 % under on-farm conservation than under ex-situ conservation. Compared with the ex-situ conservation approach, rice landraces under on-farm conservation programs had more alleles and higher genetic diversity. In every site we investigated, ethnic traditional cultures play a positive influence on rice landrace variety diversity and genetic diversity.

Conclusion

Most China’s rice landraces were conserved in the ethnic areas of southwest China. On-farm conservation can effectively promote the allelic variation and increase the genetic diversity of rice landraces over the past 35 years. Moreover, ethnic traditional culture practices are a crucial foundation to increase genetic diversity of rice landraces and implement on-farm conservation.

     

Complementarity between Geographical and social patterns in the preservation of yam (Dioscorea sp.) diversity in Northern Benin

This study was undertaken to contribute to the sustainable management of yam (Dioscorea sp.) diversity in Benin. We surveyed 220 farms from eight different villages in the north part of Benin. We hypothesized that the richness of yam cultivars is more related to farmers’ ethnic group than to their geographical location. Cultivar diversity may differ from one ethnic group to another within a given area, but remains constant for a given ethnic group independent of its geographical location. This study identified 182 yam cultivars in the region; however, only a few farmers on a very small scale marginally produce more than 50% of that total richness. Cultivation practices as well as historical and socio-cultural determinants played important roles in the creation and maintenance of yam diversity within each ethnic group. The Bariba and the Gando ethnic groups, having developed yam cultivation since time immemorial, still hold the most diverse collection of yam varieties. The access of farmers to main roads and the availability of arable and in a given village greatly influenced the overall yam diversity in the region. This study highlighted the need to combine social determinants and geographical patterns in the conservation of agricultural diversity in Benin.     

Niger-wide assessment of in situ sorghum genetic diversity with microsatellite markers

Understanding the geographical, environmental and social patterns of genetic diversity on different spatial scales is key to the sustainable in situ management of genetic resources. However, few surveys have been conducted on crop genetic diversity using exhaustive in situ germplasm collections on a country scale and such data are missing for sorghum in sub-Saharan Africa, its centre of origin. We report here a genetic analysis of 484 sorghum varieties collected in 79 villages evenly distributed across Niger, using 28 microsatellite markers. We found a high level of SSR diversity in Niger. Diversity varied between eastern and western Niger, and allelic richness was lower in the eastern part of the country. Genetic differentiation between botanical races was the first structuring factor (Fst = 0.19), but the geographical distribution and the ethnic group to which farmers belonged were also significantly associated with genetic diversity partitioning. Gene pools are poorly differentiated among climatic zones. The geographical situation of Niger, where typical western African (guinea), central African (caudatum) and eastern Sahelian African (durra) sorghum races converge, explained the high observed genetic diversity and was responsible for the interactions among the ethnic, geographical and botanical structure revealed in our study. After correcting for the structure of botanical races, spatial correlation of genetic diversity was still detected within 100 km, which may hint at limited seed exchanges between farmers. Sorghum domestication history, in relation to the spatial organisation of human societies, is therefore key information for sorghum in situ conservation programs in sub-Saharan Africa. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Farmers Drive Genetic Diversity of Thai Purple Rice (Oryza sativa L.) Landraces

Purple or black rice (Oryza sativa L.) is a culturally important germplasm in Asia with a long history of cultivation in northern Thailand. Purple rice is identified by the color of the rice pericarp, which varies from purple to black with the accumulation of phenolic acids, flavonoids, and anthocyanins. In the present study, we assessed molecular variation within and between wetland purple rice landraces germplasm from northern and northeastern Thailand using 12 microsatellite loci. All purple rice varieties surveyed showed high levels of homozygosity within varieties and strong genetic differentiation among varieties, indicating the fixation of genetic differences among them. This pattern is consistent with purple rice farming practices in northern Thailand, where a small portion of harvested seed is selected and replanted based on farmers’ preferences. The reduced genetic diversity and high homozygosity observed for purple rice is also consistent with patterns expected for this inbreeding crop. Genetic differentiation among the varieties showed some degree of structuring based on their geographical origin. Taken together, these data highlight that the genetic diversity and structure of wetland purple rice landraces is shaped by farmer utilization and cultivation through local cultural practices, and that conservation should focus on ex situ conservation across its cultivation range, along with on-farm, in situ conservation based on farmers’ seed-saving practices. In situ conservation may prove especially valuable for preserving the genetic identity of local varieties and promote adaptation to local environments.

     

水稻品种化感特性与农艺性状的关系

选用9个华南地区主栽水稻品种,用特征次生物质标记方法测定它们的化感指数,并通过田间实验确定这些水稻品种的抑草效应及主要农艺性状,在此基础上分析这些水稻品种的化感特性、抑草效应和农艺性状的关系.结果表明,具有化感特性的水稻品种并不都能在田间表现出抑草效应,化感特性与主要农艺性状均无显著的相关性,但同时具有化感特性和有利竞争农艺性状的水稻品种均能在田间显示抑草效应.水稻化感特性和农艺性状的不相关显示化感特性转入相关的水稻品种将不影响它们的农艺性状,这意味着能培育出各种农艺性状的水稻化感新品种.