Varietal Richness Research Articles

Chemometric and Physico-Chemical Characterization of Fruit and Olive Oils from Autochthonous Cultivars Grown in Aragon (Spain)

Olive tree crops and the olive oil market are becoming less and less diverse due to the rise of intensive growth varieties, with the consequent loss of varietal richness provided by oils from minority and autochthonous cultivars. "Royal de Calatayud" and "Negral de Sabiñán" are two local minority cultivars in Aragon (Spain). Fruit parameters such as ripening, fresh weight, and oil yield were evaluated, as well as physico-chemical and chemical composition parameters in olive oil in comparison with "Arbequina", a cultivar widespread in Spain and other countries. Fruits were harvested from October to December in 2017 and 2019. Chemometric analysis revealed significant varietal differences among the three cultivars. In comparison with "Arbequina", higher oil yields were obtained in the two local cultivars. "Royal de Calatayud" has a higher oleic acid content and a greater quantity of phenolic compounds. It thus displays a better nutritional profile than "Arbequina". This preliminary study shows that "Royal de Calatayud" could be regarded as an excellent alternative to the "Arbequina" cultivar in the parameters analyzed.

Agrobiodiversity dynamics in a French wine-growing region

Agrobiodiversity is a promising nature-based solution in the pursuit of sustainable agriculture. In wine-growing systems, commercial pressure and varietal regulations have narrowed agrobiodiversity in vineyards despite higher diversity being an important buffer against the effects of climate change. If drivers of grape diversity change are well-understood at national to global scales, little is known about the local, past or anticipated trajectories that drive agrobiodiversity dynamics depending on growers’ cultural values, practices and choices. We combined quantitative agricultural census data and qualitative ethnographic approaches to characterise changes in the diversity of grape varieties from 1960 to 2020 at the communal and vineyard levels in a French wine-growing region, and to decipher the drivers of change. We highlight that vineyards have drastically changed in 60 years, with a decline in planted area and in farm number. We outline that despite a loss of varietal richness across both vineyard and communal scales, varietal richness remains high and evenness have increased across geographic scales in 2020. Ethnographic field observations emphasize that growers account for external drivers (e.g., market changes, regulation and policy, technology, environmental), but also cultural values when they choose which grape varieties to plant. Grape diversity was maintained despite market integration as an insurance to spread production risk, mitigate market volatility and address environmental uncertainties. Securing livelihoods in the midst of market changes has been a major concern for growers over the last six decades and remains so. Despite a pessimistic future vision of the vineyard shared by most growers, the Gaillac region has a cultural heritage that values diversity and that thereby supports adaptation to climate change. We expect that environmental factors may play a more important role in grape selection and planting sites in the future under the influence of climate change and pesticide reduction policies. In order to expand individual initiatives resulting in diversified grape selection, growers need to be better connected with stakeholders at a variety of institutional levels.

Riqueza varietal de vid (Vitis vinífera L.) del Valle de Majes, Perú: Identificación, caracterización morfológica, análisis ampelográfico y genético

The “Majes Valley” in the province of Castilla – Arequipa Region, with a tradition in the production of wine and pisco, from grapevines introduced in the mid-sixteenth century, which are still preserved by some producers, with little knowledge of the varietal richness they possess, generating confusion in the identification of varieties and devaluing their winegrower potential. In this work, a varietal survey was carried out by wine-growing areas, characterizing the local varieties of old vineyards, with 14 primary descriptors recommended by the OIV-2009 and genetically identifying a sample of 11 phenotypes with the use of 9-SSR molecular markers when compared in the VIVC international database record. Seven wine-growing areas of the valley and 39 varieties with local names were identified, initially forming 13 groups of different names, which when analyzed by means of the canonical discriminant analysis and of main components, high inter- and intra-group phenotypic variability is evidenced due to the influence of some characters. In the analysis of the berry color the blue-black coloration predominates. Four varieties registered in the VIVC were genetically identified, corresponding to ´Listan Prieto` (syn. Negra Criolla and Moscatel), ´Quebranta` (syn.Vinera), ´Muscat Hamburg` (syn.Italia Negra) and ´Jacquez` (syn. Borgoña Majeña) and 2 unregistered varieties “Cantarita” and “Aceituna de Cotahuasi”. A varietal diversity with characteristics of interest in viticulture and plant breeding is observed, with contribution to the varietal identity of known and new creole varieties, contributing to the heritage value of the vine.

The Relevance of Discovering and Recovering the Biodiversity of Apulian Almond Germplasm by Means of Molecular and Phenotypic Markers.

Almond cultivation has great traditional and economic relevance in Southern Italy, especially in the Apulia region, where almond trees feature an ample and ancient varietal richness. To contrast the loss of plant genetic erosion and to safeguard the available bioresources, as well as to reinforce the local production, the regional Re.Ge.Fru.P. project aimed to re-evaluate, identify, and characterize the Apulian almond germplasm that is still uncharacterized and not jet studied using a dual (genetic and morphological) approach. Collection was conducted in the regional territory of 187 among the most widespread and minor or marginalized genotypes that were molecularly fingerprinted by means of 18 nuclear microsatellites (simple sequence repeats, SSRs). The high number of scored alleles reflected the great level of diversification within the Apulian germplasm, as also confirmed by neighbor joining and structure analysis, that clearly distinguished different genotype clusters. The phenotypic characterization using 17 morphological and phenological descriptors mirrored the genetic results, revealing a high degree of variability. The morphological traits with the best discriminatory ability were nut ventral suture, shell softness and shape and petal color. This work emphasizes the importance of recovering the genetic variability of Apulian almond germplasm, and the need to promote added value and enhance the local agri-food economy.

An integrated model to study varietal diversity in traditional agroecosystems.

Agricultural diversity is one of the bases of traditional agroecosystems, having great environmental and cultural importance. The current loss of agricultural diversity is causing serious concern, mainly because of its essential role in supporting global and local food security. Stopping this loss requires a better understanding of how diversity is managed locally and what mechanisms sustain agricultural diversity. Here we propose a generalist agent-based model that couples biological, cultural, and social dynamics to obtain varietal diversity as an emergent phenomenon at the community level. With a mechanistic approach, we explore how four of the model dynamics can shape systems diversity. To validate the model, we performed a bibliographic review on Manihot esculenta and Zea mays case studies. The model yielded compatible results for manioc and maize varietal richness at both community and household levels.

Trends in Varietal Diversity of Main Staple Crops in Asia and Africa and Implications for Sustainable Food Systems

Crop species and varietal diversity on farm have the potential to trigger multiple regulating and provisioning ecosystem services. The latter is commonly assessed through targeted studies covering a select number of geographies and crop species, precluding comparisons across crops and at scale. This study draws on a large dataset on the varietal release dynamics for 11 major food crops in 44 countries of Asia and Africa to assess trends in diversity across crops and regions with a 50-year perspective. Our results show an increasing reduction of crop varietal diversity linked to the spatial displacement of traditional landraces. This trend occurs at a faster rate in Asia than in Africa. So-called mega varieties tend to increasingly dominate agricultural landscapes, adding to spatial homogeneity. We further found a negative association between varietal richness and its relative abundance, challenging the relationship between crop improvement and varietal diversity. Our results show that among cereal, pulse, and root and tuber crops, varietal diversity is lowest for cereals in Asia and highest for root and tubers in Africa. The analysis contributes new information useful to prioritize crops for which increasing varietal diversity may lead to more sustainable food systems.

Pheno-genetic studies of apple varieties in northern Pakistan: A hidden pool of diversity

Apple (Malus × domestica) is a main fruit crop of cold temperate regions and traded globally. Despite being a comparatively well documented plant cultigen, available germplasm in many remote regions is still unexplored and threatened. Increasing market demands for modern cultivars and farmers’ preference for high yields may lead to the gradual loss of indigenous varieties. Gilgit-Baltistan in northern Pakistan – a mountainous and remote apple growing region – was selected to study local cultigen diversity by assessing varietal richness and diversity, arboriculture activities as well as phenotypic and genotypic characters of available germplasm. In total, 106 individual apple trees were sampled, and 35 tree owners from seven villages of the two valleys Ishkoman and Baltistan were interviewed. Dendrometric parameters, fruit traits (qualitative and quantitative), and varietal diversity in each village were measured. Genetic variation was estimated using eleven SSR markers and synonyms and homonyms were identified based on cluster analysis.Sixty-one multi-locus genotypes (MLG; mean genotype diversity: 58 %) and 18 putative clones (comprising 2 to 9 ramets) were identified. Varietal diversity was highest in Baltistan where even a wild apple relative (Malus baccata) was discovered. Mean genetic diversity was moderate (He = 0.677), while negative inbreeding coefficients indicated excess of heterozygotes in three genetic clusters. A moderate correlation (r = 0.627, p = 0.001) between phenotypic and genetic dendrograms suggested genetically linked fruit traits, which merits further exploration.Considering the high genetic and phenotypic variability, Gilgit-Baltistan appears a promising source of apple germplasm for future breeding programs. The promotion of local varieties may allow farmers to diversify their produce and derived sources of income as well as to maintain a historically important bio-cultural heritage of Gilgit-Baltistan. To this end, comprehensive conservation strategies combined with further participatory research will be needed.

Landscape-dependent effects of varietal mixtures on insect pest control and implications for farmer profits.

Intraspecific plant diversity can significantly impact insect herbivore populations in natural systems. Yet, its role as an insect pest control strategy in agriculture has received less attention, and little is known about which crop traits are important to herbivores in different landscape contexts. Moreover, empirical economic analyses on the cost‐effectiveness of varietal mixtures are lacking. We used varietal mixtures of Brassica oleracea crops on working farms to examine how two metrics of intraspecific crop diversity, varietal richness and number of plant colors (color richness), affect crop damage and the incidence and abundance of two insect pest species: Pieris rapae and Phyllotreta spp. We evaluated the context‐dependency of varietal mixtures by sampling early‐ and late‐season plantings of B. oleracea crops in farms across a gradient of landscape composition. We developed crop budgets and used a net present value analysis to assess the impact of varietal mixtures on input and labor costs, crop revenues, and profit. We found context‐dependent effects of varietal mixtures on both pests. In early‐season plantings, color richness did not affect Phyllotreta spp. populations. However, increasing varietal richness reduced Phyllotreta spp. incidence in simple landscapes dominated by cropland, but this trend was reversed in complex landscapes dominated by natural habitats. In late‐season plantings, color richness reduced the incidence and abundance of P. rapae larvae, but only in complex landscapes where their populations were highest. Varietal richness had the same effect on P. rapae larvae as color richness. Unexpectedly, we consistently found lower pest pressure and reduced crop damage in simple landscapes. Although varietal mixtures did not affect crop damage, increasing color richness corresponded with increased profits, due to increased revenue and a marginal reduction in labor and input costs. We demonstrate varietal mixtures can significantly impact pest populations, and this effect can be mediated by intraspecific variation in crop color. However, the strength and direction of these effects vary by season, landscape composition, and pest species. The association between varietal color richness and profitability indicates farmers could design mixtures to enhance economic returns. We recommend additional research on the benefits of intraspecific trait variation for farmers.

Diversity, use and production of farmers’ varieties of common bean (Phaseolus vulgaris L., Fabaceae) in southwestern and northeastern Ethiopia

Legumes are a critical component of many agricultural systems and a major contributor to global food systems. Common bean (Phaseolus vulgaris L.) is the most widely grown legume crop in Ethiopia. It is an important source of food, income, and soil fertility management in southwestern (SW) and northeastern (NE) Ethiopia, and used as medicine, fodder, and honeybee forage in the NE. Diversity and use of farmers’ varieties of common bean (Phaseolus vulgaris) bean were investigated in five administrative zones in SW and NE Ethiopia. Structured and semi-structured interviews were conducted with 288 general informants and 48 key informants in five agroecological zones inhabited by four cultural groups. Thirty-nine varieties were identified based on farmers’ naming practices. Varietal richness and diversity were found to be highest in the humid, tepid mid-highlands of Kefa (13) and Bench Maji and Sheka (12). However, farmers in both research areas typically plant only one or two varieties. Interestingly, the number of varieties per household was highest (2.3) in South Wollo Zone of the NE, where only six varieties were found. We find that varieties per household are limited by small landholdings in the SW and varietal richness in the NE. Given these limitations, policies and programs to conserve varietal diversity and increase productivity are more likely to be effective if organized at the community level in the SW and the household level in the NE. Agromorphological and genetic characterization of common bean varieties would facilitate the management and conservation of their diversity as a source of resilience.

Combination of Simple Sequence Repeat, S-Locus Polymorphism and Phenotypic Data for Identification of Tunisian Plum Species (Prunus spp.).

Plums (Prunus spp.) are among the first fruit tree species that attracted human interest. Artificial crosses between wild and domesticated species of plums are still paving the way for creation of new phenotypic variability. In Tunisia, despite a considerable varietal richness of plum as well as a high economic value, the plum sector is experiencing a significant regression. The main reason of this regression is the absence of a national program of plum conservation. Hence, this work was aimed to phenotypically and genetically characterize 23 Tunisian plum accessions to preserve this patrimony. Closely related Prunus species from the same subgenus may be differing at two characteristics: ploidy level and phenotypic traits. In this study, single sequence repeat (SSR) markers allowed distinguishing between eighteen diploid accessions and five polyploid accessions, but SSR data alone precluded unambiguous ploidy estimation due to homozygosity. In contrast, S-allele markers were useful to identify the ploidy level between polyploid species, but they did not distinguish species with the same ploidy level. Seven out of 12 phenotypic traits were shown to be discriminant traits for plum species identification. Molecular and phenotypic traits were significantly correlated and revealed a powerful tool to draw taxonomic and genotypic keys. The results obtained in this work are of great importance for local Tunisian plum germplasm management.

Quantitative Analysis, Distribution and Traditional Management of Pigeon Pea [Cajanus Cajan (L.) Millsp.] Landraces’ Diversity in Southern Benin

Pigeon pea (Cajanus cajan (L.) Millsp.) is an important drought tolerant legume cultivated in the semi-arid regions, mainly in Sub-Saharan Africa. Despites its important potential, the crop is neglected and underutilized in many countries including Benin. In order to develop efficient in-situ strategies conservation, a study was conducted to quantify pigeon pea landrace diversity and access its spatial distribution and traditional management by local communities in southern Benin. Therefore, an ethnobotanical survey was conducted in 20 producing villages in southern Benin. Altogether, 26 farmernamed landraces further grouped into five categories were recorded with the number of landraces really cultivated per farmer comparably lower than that listed. Besides, two landraces’ categories were found to be common in the study area while two other were found highly threatened. Diverse parameters such as varietal richness, Shannon-Weaver Diversity Index, Simpson index and Pielou’s evenness were used to quantify pigeon pea diversity that appeared to be unequally distributed through the different agro-ecologies and villages surveyed. The study confirmed the absence of correlations between farmers’ gender and landrace diversity which was nonetheless found to be significantly shaped by the ethnic group and the field size exploited by farmers (P < 0.05). In diversity management, five preference criteria with variable importance across the ethnic groups were used by farmers of which cooking time and market value appeared to be the most important. Exhaustive germplasm collections, morphological/molecular characterizations of these landraces are required for efficient conservation of this important but neglected crop genetic resource in Benin.

Maize (Zea mays L.) management in Yaxcaba, Yucatan, during the twentyfirst century’s first decade is consistent with an overall loss of landrace diversity in southeast Mexico

The status of genetic resource conservation in centers of crop diversity remains disputed. Recent case-study findings of persistent maize diversity in Yaxcaba, Yucatan, a municipality in southeast Mexico, have raised questions on earlier reports of widespread losses across the crop’s center of diversity in Mexico. We break down patterns in maize varietal richness in southeast Mexico to show that temporal trends in Yaxcaba are subsumed under spatial variation in this broader region and consistent with an overall loss of diversity. Persistence of diversity in Yaxcaba can be explained by conditions that allowed subsistence farmers to continue sowing land even as maize prices dropped, but these conditions may be rare in Mexico and likely to change. Yaxcaba emerges as a rare community of exceptional diversity from which valuable policy lessons can be drawn. We find that gaps and omissions in the Mexican Government’s strategy for maize conservation have excluded Yaxcaba and likely resulted in an ineffective intervention elsewhere in the Peninsula. An integrated-systems perspective should help us develop a coherent strategy for resource conservation and climate adaptation based on more efficient and equitable instruments.

Temporal evolution of varietal, spatial and genetic diversity of bread wheat between 1980 and 2006 strongly depends upon agricultural regions in France

An in-depth analysis of the spatio-temporal evolution of crop diversity in agricultural landscapes is necessary to provide insights on how to improve the resilience of agroecosystems to climate instability and new pest pressures by increasing in situ crop diversity, while promoting a greater sustainability of agriculture. However, most of the indicators of crop diversity used in previous studies were based on ex situ genetic diversity, or on official lists of varieties or breeding programs, without taking acreage of the varieties actually grown in farmers’ fields into account. Acreage of varieties represent however a relevant information to assess the actual genetic vulnerability of a crop (genetic uniformity at landscape scale) cultivated in the considered regions over the period studied. To bridge this gap, we analyzed spatial varietal and genetic diversity of bread wheat in France – an important production area – over the 1980–2006 period at a yearly time step and a district scale, i.e. ‘département’. We used HT*, an indicator integrating both the spatial evenness of variety distribution and molecular genetic data, to finely examine the spatio-temporal evolution of spatially weighted bread wheat genetic diversity. We also computed several simpler and complementary indicators accounting for the number of varieties, the spatial varietal diversity and the genetic diversity, and we estimated the individual contribution of these simpler indicators to the spatio-temporal structure of the spatial genetic diversity HT*. HT* values showed significant but non linear temporal evolutions between 1980 and 2006, these evolutions being besides spatially structured. Moreover, both spatial varietal diversity and genetic diversity partly explained these temporal changes of HT* values while the number of varieties appeared non-explanatory. Similarly to HT*, all indicators studied also showed substantial differences of temporal changes among major French agricultural regions, furthermore sometimes opposite for varietal and genetic diversity. As an example, in the north of France, varietal richness and spatial varietal diversity showed a substantial increase, suggesting the adoption of an increasing number of bread wheat varieties by farmers in this region. However, considering that genetic diversity showed a slight but continuous decrease over the recent period, this could suggest an increase in genetic similarity among bread wheat varieties chosen by farmers. Taken as a whole, our results suggest that several determinants of crop diversity, such as the shortening of crop sequences or the recurrence of epidemics of some pathogens, could differentially affect varietal choices of farmers and thus the spatial structuration of the temporal changes of crop diversity. Finally, our results question the dominant use of ex situ nationwide datasets to characterize the evolution of spatial genetic diversity as a proxy of genetic vulnerability of a crop to face with future changes.

English

Local sorghum varieties managed and cultivated by farmers contribute in a large part in crop production of Burkina Faso. The loss of local sorghum varieties were reported, but very few investigations have been made on it. This study was conducted to assess the status of 739 local sorghum varieties collected in four regions of Burkina Faso and to identify the threats factors of sorghum diversity. A sample of 159 varieties identified as “rare” and described by the cycle length, the uses and disadvantageous characteristics has been submitted to a Multiple Correspondence Analysis (MCA) to determine sorghums groups and characterize them. The results showed a higher varietal richness in the North, East and Centre-East regions compared to the South-West region, with respectively 13.0; 11.7; 10.9 and 6.1 varieties per village. The MCA underlined four main groups of sorghum: custom sorghums, lain period sorghums and tincture sorghums, pharmacopeia sorghums and sweet-stem sorghums; they are characterized by lateness associated to the low grain productivity, earliness associated to the low grain quality, drought sensitivity. For these sorghums groups it appears that the climatic and socio-cultural changes are the main threats factors of sorghum diversity loss. Farmers' associations at regional level and research structures should in common develop suitable initiatives to follow-up and conserve sorghum diversity. Key words: Sorghum, local varieties, lateness, decline of uses, erosion.

A novel index to quantify agrobiodiversity in a biocultural perspective: the case of shifting cultivation gardens in Vanuatu (Pacific)

ABSTRACTShifting cultivation is the most widespread agroforestry system in the tropics that may contribute to biodiversity conservation under certain conditions. Despite their common use, traditional biodiversity indexes prove ill-suited for assessing complex systems of this type. This study proposes a novel index, AGB, to assess agrobiodiversity in systems that mix species, varieties, lifeforms, and uses. The AGB index was tested using agrobiodiversity inventories in Vanuatu, where we compared agrobiodiversity levels and patterns of change over the course of a crop cycle between different field types. The 297 sampled fields contained a total of 127 species with an average of 10.1 species and of 11.6 varieties per field. During the cropping cycle, species and varietal richness diminish. The AGB index was compared with the Shannon and Pielou indexes and proved to be accurate for assessing and monitoring agrobiodiversity at the species and varietal levels. It may be a useful tool for agrobiodiversity monitoring in agricultural systems undergoing changes in practices and for achieving a better understanding of their biocultural resilience.

Somaclonal variants of taro (Colocasia esculenta Schott) and yam (Dioscorea alata L.) are incorporated into farmers’ varietal portfolios in Vanuatu

Taro (Colocasia esculenta) and the greater yam (Dioscorea alata) are staples in Vanuatu. The aim of the present study was to assess the role of somaclonal variations in the varietal diversification of these two clonally propagated crops. The study was conducted in six villages located each on distinct islands of Vanuatu, Melanesia. Overall, 203 varieties of taro and 80 varieties of yam were collected and DArTs were used for analysis. The overall quality of the DArT markers was high for both species. The percentage of polymorphic clones detected on the DArT array was low for taro (3 %) and high (13 %) for yam, with respectively 202 and 499 polymorphic clones. Each variety was characterized by its multilocus genotype based on its DArT presence/absence profile. For taro, the 203 varieties were represented by 126 unique genotypes and 34 distinct multilocus lineages (MLLs). The high number of unique genotypes and the presence of few varieties sharing a clonal origin, generated a high varietal richness index (R = 0.83). For yam, the 80 varieties were represented by seven unique genotypes and 16 MLLs. The low number of unique genotypes and the presence of numerous varieties sharing a clonal origin generated a low varietal richness index (R = 0.26). Possible factors contributing to these contrasting results are discussed. DArT markers provide evidence that somaclonal variants of taro and yam are selected as new varieties. Strategies aiming at strengthening communities’ capacity to adapt to forthcoming changes should consider the introduction of allelic diversity into farmers’ varietal portfolios.

Recovery and identification of grapevine varieties cultivated in old vineyards from Navarre (Northeastern Spain)

The reconstitution of European vineyards after the phylloxera outbreak was performed with few high-aptitude varieties. In Navarre (Spain), the variety used was mainly ‘Garnacha’, though the inclusion of a small number of plants of different varieties traditionally grown in this area within each vineyard was relatively frequent. In this context, in 2008 and 2009, a systematic survey was performed on the oldest vineyards (>50 years) from Navarre in order to gather the intravarietal diversity that could be found within ‘Garnacha’ in the region, but subsequent field observation showed 197 plants to be different from ‘Garnacha’. The aim of this study was to identify the varieties corresponding to those plants. Molecular profiles were determined using 25 SSR markers, and 33 varieties were identified: 28 of them after comparisons with national and international databases and the remaining five through other sources. Slight differences in SSR allele length were found in some of the plants identified as ‘Mazuelo’, ‘Rojal’, ‘Miguel de Arco’ and ‘Tortozona Tinta’. In addition, polymorphisms involving the appearance of a third allele were found in some plants identified as ‘Viura’, ‘Mandón’, Mazuelo’ and ‘Morate’. This study shows that an important biodiversity reservoir still remains within old vineyards and, therefore, systematic surveys on them could allow gathering the varietal richness that still can be found in the region. Additionally, somatic variation at SSR loci has been shown to occur in several grape varieties, especially in the ancient ones where the likelihood that mutations are accumulated and fixed is higher.

Origins, Functions, and Persistence of Crop Biodiversity in the Betsileo Highlands, Madagascar

In order to assess Malagasy crop biodiversity (CB) richness and stability on a regional scale, an analysis at both species and variety levels was carried out in the Betsileo area of the Madagascar Highlands. The study zone was a transect between the humid forest zone and the drier savanna. Peasant agriculture is faced with the challenges of a fast–growing resident population, government development and forest conservation-based policies. Sampling was done at two scales: five villages and 45 farms representative of three main farm types (small and poor, medium–sized, and richer farms). Farm surveys were conducted to collect data on several aspects of CB: taxonomic richness, functions, origin, date of introduction, rarity, and threats. Forty–five species were recorded altogether. The number of species in each village varies from 27 (a forest village) to 41 (a savanna village). Sixteen species are omnipresent in the area: they constitute the common base of Betsileo agriculture. On the farm scale, species diversity is high everywhere: each farm grows half the species present in its village, but only several varieties thereof. Yet the six main species include 57 varieties in all, of which 46% are ancient and 76% are hardy landraces. The bigger farms grow significantly fewer varieties than smaller, poorer farms. Successful varietal introductions have not reduced local varietal diversity. Regional and local varietal richness of a species is closely linked to the number of varieties per farm, depending on local importance, ecological suitability, and risk management, and is increased by seed exchanges. Betsileo agriculture appears to be simultaneously dynamic and faithful to its risk strategies, way of life, and values, allowing conservation of its technical, genetic, and cognitive capital. Current individual practices of conservation of rare varieties through small collections and seed exchanges should be supplemented by collective actions.

On-farm conservation of 12 cereal crops among 15 ethnic groups in Yunnan (PR China)

Due to the rapid diffusion of improved crop varieties, fewer and fewer landraces are being grown by farmers. The on-farm conservation of crop landraces has been proposed as means of conserving potentially important crop germplasm as an alternative to its ex situ conservation in gene banks, but the effectiveness of this approach is unproven. Particular attention is currently focused on producers sited in remote regions. Here, we report the outcomes of a survey focusing on the conservation and utilization of landraces of corn, rice, wheat, barley, buckwheat, broomcorn sorghum, Job’s tears (coix), oats and finger, foxtail, broomcorn and barnyard millets grown by 15 ethnic groups from Yunnan province (China). Many local varieties are still in existence through their utilization on-farm. The varietal richness per village sampled was estimated to be 3.5 (maximum of 17), with rice and maize being the most heterogeneous, and glutinous sorghum and barnyard millet the least. Varietal richness was significantly and positively correlated with the number of villages surveyed, the number of families and the head of population. The choice of crops and varieties maintained varied between the ethnic groups, with the more westerly and north westerly situated villages conserving the most landraces. The number of crop species used was negatively correlated with per capita annual income, while the correlation coefficient between varietal richness and per capita annual income was less pronounced. The major factors determining the level of on-farm conservation were remoteness, fragmentation of the arable area and cultural needs. The data provide baseline information for the elaboration of optimal strategies for in situ conservation and utilization of crop germplasm in China.

A new integrative indicator to assess crop genetic diversity

Various international initiatives have emerged to develop new sets of biodiversity indicators for wild biodiversity but little progress has been made for crop diversity. This study proposes a new methodology to assess the diversity of cultivated species. We developed a new integrative indicator HT* that takes account of varietal richness, spatial evenness, between-variety genetic diversity, and within-variety genetic diversity. This index is compared to existing indexes using a comprehensive historical dataset from a French territory. The study reveals that more varieties (the varietal richness factor) can mean less diversity when (i) their genetic structure is more similar (the effect of between-variety genetic diversity), or (ii) when more diverse landraces are replaced by many homogeneous lines (the effect of within-variety genetic diversity) or (iii) when one or a few varieties become hegemonic in the landscape (the spatial evenness effect). Furthermore, an increased evenness in variety distribution (varietal evenness) can also mean less diversity when varieties are genetically related. This is why indicators which do not take into account the full range of factors (varietal richness, between-variety genetic diversity, spatial evenness and within-variety genetic diversity) may provide a misleading assessment of the state and trend of crop biodiversity. New integrative indicators such as HT* are critically needed. We discuss potential further development such as the use of this indicator for monitoring and the perspective of a broader indicator to assess genetic diversity at the multi-species scale and landscape level. In the future, this indicator could be used to guide managerial decisions to prevent the erosion of crop genetic diversity in agricultural landscapes.