17个玉米地方种质选系的配合力分析

分析玉米地方种质选系的配合力,可以为探明自交系的应用价值提供技术支撑。选用11个自交系为测验种,采用不完全双列杂交设计,对17个玉米地方种质新选的自交系的配合力、杂种优势以及主要性状遗传参数进行了分析。结果表明:单株产量GCA表现突出,且构成产量因子性状GCA表现也较好的新选自交系有P1-1、P1-16和P1-14;SCA值高、杂种优势强的组合是P2-4×P1-10;在株高、穗位高、穗行数等4个性状中,亲本的基因加性效应对F1性状形成起主导作用,而穗长、秃尖长、百粒质量等5个性状的遗传变异主要来自于基因非加性效应。因此,对于高产组合的选配,至少要选择1个GCA高的材料作亲本,并在此基础上兼顾SCA的选择,而利用地方种质选系则应根据性状遗传特性决定其选择时期和选择强度。     

Production and use of maize seed for sowing in Bolívar,Ecuador

In the province of Bolívar in the Andean region 212 farmers, six salesmen and 14 technicians, involved in maize production, were interviewed. The majority of the farmers interviewed were small-holders; 64% of the farmers had a farm size of less than 4.5 ha. Maize is the most important crop and is often grown in association with beans. Most maize, 96%, is soft maize meant for human consumption. The cultivars grown are open pollinated ones. One cultivar, ‘Guagal’, was grown extensively. A few others, among which an improved version of Guagal were of some importance. In the production of maize the farmers consider damage due to insects, wind (lodging), diseases, drought and hail, the low prices for their surplus maize and the high costs of fertilizers, chemicals, sowing seed and labour as the most important constraints. The seed for sowing the next crop mainly came from seed kept from the last harvest. Farmers indicated that they select from the harvested ears the healthy looking larger ones. Kernel type also was a selection criterion. Selection for plant type in the field was rarely done. Of the farmers 71% stored the maize as kernels while 29% stored the seed kept on the ears. The storage was predominantly done somewhere in the house in plastic (56%) or cloth bags (14%), in a pile (13%), just on the floor (4%) or in cans (4%). Some farmers still had seed left from the last sowing and were willing to give a sample for testing. From 32 such samples the quality was assessed by INIAP, the Ecuadorean governmental research and breeding organisation. The samples were consistently of a low quality. Especially the vigour of the seedlings was poor and most of the seeds were infected or contaminated by fungi. In the region a few salesmen offer maize seed for sale of cultivar Guagal at prices affordable by the farmer. Of improved cultivars the prices were higher than most farmers are willing to pay. The technicians considered good seed quality and good maintenance of the cultivars effective methods in obtaining better yields. Many farmers do not have access to seed of INIAP and are not familiar with the improved cultivars.     

Trade-offs between on-farm varietal diversity and highly client-oriented breeding — a case study of upland rice in India

On-farm varietal diversity is now highest in marginal agricultural environments because, unlike the case in more favourable areas, modern varieties have not been a sufficiently attractive option for farmers to replace their landraces. However, the continued survival of landraces on farm is dependent on the continuing failure of plant breeding to provide better alternatives. Highly client-oriented breeding can produce suitable modern varieties for areas that were dominated by landraces. We examine here the case of the adoption of two upland rice varieties in three states in eastern India, Jharkhand, West Bengal and Orissa, where our surveys had confirmed low adoption of modern varieties in the upland ecosystem. The two new upland varieties were readily accepted by farmers who rapidly adopted them on large proportions of their land. On-farm diversity is maintained by the need to trade-off among varieties but once a variety with overall superiority was found this incentive was removed. The new varieties from the client-oriented breeding did not have weaknesses that farmers had to trade-off against their landraces so they were more likely to replace them. They also replaced older modern varieties. Farmers had previously maintained them along with landraces because they had to trade-off the higher yield of Kalinga III against the more stable yield of landraces or the higher yield of Vandana against the higher gain quality of the landraces. Only mean count per household could be used to test the significance of the differences between individual years. In all states, this revealed a significant reduction in landrace diversity with the adopting farmers when the addition of the two new varieties was not considered. Trends across years for mean varietal count, total count and Shannon–Wiener index showed a significant decline in Orissa, irrespective of whether the two new varieties were included in the analysis or not. In Jharkhand there was a significant decline only for mean count when the new varieties were not included. In Orissa, it was possible to test if rare landraces were as readily replaced as more common ones. Landrace replacement was unmitigated by increasing rarity yet the most rare landraces have the highest priority for genetic conservation. Some landraces were completely replaced by the farmers in the sample despite a diverse variety portfolio being a risk-reducing strategy in a region where there is a high risk of crop failure. There was little environmental heterogeneity in the marginal, drought-prone areas to slow this decline. The new varieties had an impact on the farming system because sometimes farmers brought additional upland into cultivation. They also introduced these varieties into more favourable, medium land. The strategy of releasing two new upland varieties met with some success in maintaining diversity.     

Diversity in White Lupin (<Emphasis Type="Italic">Lupinus albus</Emphasis> L.) Landraces from Northwest Iberianplateau

All the accessions (35) of white lupin (Lupinus albus L.) landraces collected from northwest Iberian plateau and maintained at the Spanish germplasm collection (CRF of INIA), were studied with the general objective of assessing the biodiversity of these landraces and to ascertain their value as genetic resources for the development of germplasm adapted to the areas where they were collected with long and chilly winters. The characterization study comprised 51 qualitative and 50 quantitative characters. Quantitative parameters were analyzed by Principal Components Analysis (PCA). The 2-dimensional plot (49.3% of cumulative variability) formed a main group of accessions and 4 outliers (#1, #9, #27 and #28) separated in the first PC. The characters with a higher contribution to the first PC were inflorescence length, leaf petiole length and leaf central foliole area. The presence of alkaloids, the percentage of plants killed by soil borne fungal diseases, the phenology, the yield per plant and yield components were also assessed. Twenty six accessions (the main group in the PCA plot) showed high homogeneity, with the following highlights: bitterness, indeterminate growth habit, early ripeness and spring sowing with the exception of #18, in which seeding date is unknown and it had a later phenology. By contrast accessions #9 and #27 were bitter of autumn sowing with determinate growing habit and they had the longest values of primary inflorescence length and a later phenology when they were sown in spring. Average values for yield and yield components showed a broad range of variation between accessions. The main yield component was the number of pods per plant. Accession #22 had the highest mean seed mass, although this had not significant influence in yield. Accession #17 showed the highest yield and #1 the lowest. This last also had the lowest values of inflorescence length, leaf petiole length and leaf central foliole area. No significant differences of resistance to soil-borne fungi were found between accessions. The year had a significant effect in the phenology, yield and yield components except for number of seeds per pod. The studied material might be of interest for the development of spring sowing germplasm adapted to north Iberian peninsula.     

A Suitable Site for in situ (On-farm) Management of Plant Diversity in Traditional Agroecosystems of Western Himalaya in Uttaranchal State: A Case Study

There is a growing realisation world over that the introduction of modern agriculture has to be supplemented with measures to conserve biodiversity in situ if yield gains are to be stabilized. Hence, there is a growing interest from agricultural development specialists and conservation biologists for understanding the socioeconomic factors determining the conservation of biodiversity in situ. The present study was conducted with the objective of understanding the in situ (on-farm) conservation of agrobiodiversity in traditional agroecosystems taking the Urgam valley in north-western Himalaya of India, as a case study. An inventory was made of traditional crops and wild economic species for subsistence, and the structure of forest resource base, traditional knowledge related to resource management and use. Institutional and scientific challenges for in situ (on-farm) management of crop diversity were studied and are discussed in this paper. Complementarity of in situ (on-farm) conservation with ex situ conservation together with crop improvement in such marginal areas are suggested.     

Diversity among landraces of Indian snapmelon (<Emphasis Type="Italic">Cucumis melo</Emphasis> var. <Emphasis Type="Italic">momordica</Emphasis>)

Diversity among 36 snapmelon landraces, collected from 2 agro-ecological regions of India (9 agro-climatic sub-regions), was assayed using RAPD primers, morphological traits of plant habit and fruit, 2 yield-associated traits, pest and disease resistance and biochemical composition (TSS, ascorbic acid, titrable acidity). Typical differences among accessions were observed in plant and fruit characteristics and snapmelon germplasm with high titrable acidity and possessing resistance to downy mildew, Cucumber mosaic virus, Zucchini yellow mosaic virus, Papaya ringspot virus, Aphis gossypii and Meloidogyne incognita was noticed in the collection. RAPD based grouping analysis revealed that Indian snapmelon was rich in genetic variation and region and sub-region approach should be followed across India for acquisition of additional melon landraces. Accessions of var. agrestis and var. momordica clustered together and there was a separate cluster of the accessions of var. reticulatus. Comparative analysis of the genetic variability among Indian snapmelons and an array of previously characterized reference accessions of melon from Spain, Israel, Korea, Japan, Maldives, Iraq, Pakistan and India using SSRs showed that Indian snapmelon germplasm contained a high degree of unique genetic variability which was needed to be preserved to broaden the genetic base of melon germplasm available with the scientific community. N. P. S. Dhillon and Ranjana contributed equally to this work and are considered the first authors.     

太湖流域糯稻地方品种资源农艺性状分析

为了充分利用地方资源有利基因拓展现代育成品种的遗传基础和改良目标性状,利用15个主要农艺性状对135个太湖流域糯稻地方品种资源进行了分析。结果表明,晚熟、株高和穗颈长偏高、着粒密度和产量偏低为太湖流域糯稻地方品种的主要特征。性状的变异系数范围为3.42%￣35.01%,单株产量、单株有效穗、每穗总粒数、每穗实粒数、穗颈长短、着粒密度等6个性状居前列。主成分分析显示,PC1-PC5能够解释总体70.4%的变异,而每穗总粒数、每穗实粒数、着粒密度、单株有效穗、株高、千粒重、单株产量等7个性状因具有高的特征向量值,为分析太湖流域糯稻地方品种资源的重要性状。以主成分分析中提取的5个公因子进行聚类分析,可将研究材料分为14类,其中第Ⅰ、Ⅸ、ⅩⅣ和Ⅻ类品种有利性状突出,是改良当地糯稻品种的极有用的种质资源。产量构成因子和单株产量的偏相关分析表明,太湖流域糯稻地方品种对产量的贡献主要是单株有效穗和每穗粒数,这也是地方品种亟待改良的重点。研究还发现,同名异种现象十分普遍。     

Diversity of Nordic Landrace Potatoes (<Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.) Revealed by AFLPs and Morphological Characters

The management of genebank collections of cultivated potato is costly due to the need for in vitro maintenance and virus eradication. Therefore, it is important to set up conservation strategies, which prevent duplicates entering the collections. In this study, 32 Nordic potato landraces were studied for 57 morphological traits and analysed for amplified fragment length polymorphism (AFLP). Most landraces could be distinguished based on the morphological characters, except five accessions. Using five primer combinations to generate 114 reproducible AFLPs, of which 63 (55%) were polymorphic, the five morphologically indistinguishable accessions were placed into two groups with identical AFLP patterns, suggesting that some of the accessions were redundant for long-term preservation. The AFLP data showed that the Nordic collection of potato landraces is composed of genetically different clones, and morphological analysis revealed a wide range of variability. This variability seems to be distributed randomly over the Nordic region since the cluster analysis based on AFLPs and morphological traits revealed no grouping based on the country of origin. Principal component analysis suggests that fewer morphological traits than used in this study will be sufficient to discriminate between different genotypes of cultivated potato (Solanum tuberosum L.). Future possibilities for rationalising potato collections are discussed.     

Genetic Erosion – Examples from Italy<Superscript>1,2</Superscript>

Italy has been used as a country for estimating genetic erosion in crops. It was possible to compare early surveys (from the 1920s to the 1950s), especially on wheats, with results of later missions in the 1980s and 1990s. In the early years, a relatively high genetic erosion was observed (13.2% p.a.). From the 1950s until the 1980s erosion rates between 0.48 and 4% p.a. were estimated. In the little island of Favignana there was an erosion rate of 12.2% p.a. leading to the extinction of the last wheat landraces of this island. There have been no significant differences in erosion rates between field- and garden-crops though there has been the impression that garden crops are better preserved over the long run. Interestingly extinction rates of wild plants (0.13% in the Mediterranean) come close to the average erosion rates of crop plants in the area. ¹Dedicated to Erna Bennett on the occasion of her 80^th birthday ²Lecture presented during the XVII^th Congress of EUCARPIA in Tulln, Austria, 2004     

Participatory landrace selection for on-farm conservation: An example from the Central Valleys of Oaxaca, Mexico

On-farm conservation is recognized as a key component of a comprehensive strategy to conserve crop genetic resources. A fundamental problem faced by any on-farm conservation project is the identification of crop populations on which efforts should be focused. This paper describes a method to identify a subset of landraces for further conservation efforts from a larger collection representing the diversity found in the Central Valleys of Oaxaca, Mexico. Mexico is a center of origin and diversity for maize (Zea mays L.). The 17 landraces selected from an initial collection of 152 satisfy two criteria. First, they represent the diversity present in the larger collection. Second, they appear to serve the interests of farmers in the region. Data for applying the method were elicited through participatory as well as conventional techniques. They incorporate the complementary perspectives of both men and women members of farm households, and of plant breeders and social scientists.