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.     

Mapping of quantitative trait loci controlling seed longevity of rice (Oryza sativa L.) after various periods of seed storage

Seed longevity varies considerably in cultivated rice (Oryza sativa L.), but the underlying genetic mechanism of longevity has not been well elucidated. Quantitative trait loci (QTL) that control seed longevity after various periods of seed storage were sought using recombinant inbred lines derived from a combination involving ‘Milyang23’(Indica‐type) and ‘Akihikari’ (Japonica‐type). In all, 12 QTLs for germination and normal seedling growth were detected as indices of seed longevity on chromosome 7 (one region) and chromosome 9 (two regions) in treated seeds that had been stored under laboratory conditions for 1, 2 or 3 years.‘Milyang23’ alleles of all QTLs promoted germination and normal seedling growth after all durations of storage. These QTL regions were detected repeatedly in more than one seed condition. Therefore, we infer that these regions control seed longevity.     

Effects of farmers' seed management on performance and adaptation of pearl millet in Rajasthan, India

Pearl millet (Pennisetum glaucum [L.]R.Br.) is the staple food and fodder crop of farmers in the semi-arid areas of north-west India. The majority of farmer sin western Rajasthan depend on their own seed production and employ different seed production strategies that involve different levels of modern-variety introgression into landraces as well as different selection methods. This study quantifies the effects of three seed management strategies on environmental adaptation and trait performance. Forty-eight entries representing farmers’ grain stocks — pure landraces or landraces with introgressed germ plasm from modern varieties — as well as 33 modern varieties, multiplied by breeders or farmers, were evaluated in field trials at three different locations over two years under varying drought-stress conditions. Results indicate that the plant characteristics employed by farmers in describing adaptive value and productivity is an effective approach in discriminating the type of millet adapted to stress and non-stress conditions. It was also found that introgression of modern varieties(MVs) leads to populations with a broader adaptation ability in comparison to pure landraces or MVs alone – but only if MV introgression is practised regularly and is combined with mass panicle selection. Under high-rainfall conditions, farmer grain stocks with MV introgression show similar productivity levels as modern varieties. Under lessening rainfall, pure landraces show, in tendency, higher grain yields. In conclusion, farmers’ seed management could form an integral part of participatory breeding programs. This revised version was published online in July 2006 with corrections to the Cover Date.     

Linking participatory plant breeding to the seed supply system

There is a strong link between formal plant breeding and seed supply. In developed countries, it was the emergence of systematic plant breeding that generated new named varieties and stimulated organized seed multiplication and marketing by commercial companies. In developing countries likewise, the experience of the ‘Green Revolution’ in the 1960’s led to the establishment in the following decade of national seed projects which could deliver the products of plant breeding more effectively from breeder to farmer. The provision of a secure conduit leading from research to agriculture remains a major justification for formal seed systems. The limitations of formal breeding approaches have been recognized in recent years, especially for crops grown in marginal and diverse environments, where farmers’ requirements are more complex. This has prompted interest in alternative participatory plant breeding strategies in which farmers can play an active role in the selection process. There has been a parallel recognition of the role of the informal seed sector, as the major seed supplier in many crops and areas where the regular sale of seed by formal organizations is difficult. The question which arise therefore is—“How do participatory breeding approaches relate to both formal and informal seed systems?” The purpose of this paper is to examine the technical, regulatory and policy aspects of this question, with emphasis on the following issues:

• The nature and definition of participatory plant breeding (PPB) outputs,
• Maintaining the identity and integrity of PPB outputs
• The relevance of official variety evaluation and registration procedures
• Maximizing the diffusion and impact of PPB outputs
• Innovative seed supply systems linked to PPB activities
• The role of policy in facilitating alternative seed delivery systems

The synthesis of this discussion is that PPB initiatives must be linked to a secure diffusion strategy within and beyond the participating communities if the technical and social benefits of this approach are to be fully realized. National policies relating to seeds and regulatory frameworks must also take account of this approach to avoid downstream constraints.     

Seed colour, seed weight and seed oil content in Linum usitatissimum accessions held by Plant Gene Resources of Canada

The purpose of this study was to investigate variation of and relationships among seed colour, seed weight and seed oil content in cultivated flax (Linum usitatissimum L. ssp. usitatissimum). Seed from 2934 flax genebank accessions recently grown at Saskatoon, SK, Canada, originating from 72 countries was used to describe the variation of the seed characters. The dominant seed colour of the accessions was medium brown (2730 accessions, 93.0%), followed by yellow (126 accessions, 4.3%). Based on single observations for all accessions, the overall mean and standard deviation was 5.95 ± 1.22 mg/seed for seed weight and 38.3 ± 1.74% for oil concentration. Within three infraspecific groups of flax, seed weight, oil concentration and oil amount per seed increased in the following order: fibre flax (convar. elongatum), intermediate flax (convar. usitatissimum), large‐seeded flax (convar. mediterraneum). The world collection exceeded the range of variation of seed weight and oil concentration found in 52 North American cultivars. There was a weak, positive association of higher oil concentration with higher seed weight (r² = 0.32; P < 0.001). Yellow‐seeded flax had a higher seed weight (6.31 vs. 5.92 mg/seed) and oil concentration (39.4% vs. 38.3%) than brown‐seeded flax. There was a tendency for yellow seed colour to be associated with higher oil concentration in all seed weight classes. The results suggested that indirect selection for increased seed oil concentration in flax is possible by selection for higher seed weight and yellow seed colour.     

Inheritance and linkage of a gene for testa-imposed seed dormancy in faba bean (Vicia faba L.)

Seed dormancy in the grain legumes may interfere with germination in some situations, yet is not well described. Dormancy in faba bean (Vicia faba L.) was investigated to determine the mode of inheritance and whether the gene or genes controlling this trait are linked to other genes. Seeds produced by 235 recombinant inbred lines at the F₆ generation were used for this study. The parents were the cultivar ‘Optica’ and 172, an Afghanistan landrace which possesses extended seed dormancy. Germination was scored on a seed sample from each recombinant inbred line. Segregation patterns indicated that the trait is monogenic. This gene, named doz, is linked to a gene controlling anthocyanin and proanthocyanidin synthesis, sp-b, with the genetic distance estimated to be about 25 cM. No associations were detected between seed dormancy and pod dehiscence, seed lustre or mean seed weight. The implications of the persistence of a gene for seed dormancy in the gene pool of V. faba for the introgression of traits from landraces and cultivars possessing dormancy and for the origins of domesticated V. faba are discussed.     

Genetic variability for seed oil content and seed index in some wild species and perennial races of cotton

A 3‐year study was made on genetic variability of seed oil content and seed index with 20 wild species, two cultivated species and six perennial races of Gossypium arboreum cotton maintained at the Central Institute for Cotton Research, Nagpur, India. The mean seed oil content varied from 10.26 to 22.89% in 22 species of Gossypium and six races of G. arboreum. In this material the weight of delinted seed varied from 43.33 to 54.54 mg/seed. The highest seed oil content was recorded in the species G. lobatum followed by G. harknessii. On average, for both traits, the means were higher for G. arboreum and its races. However, G. africanum and G. harknessii reached the level of G. arboreum and its races for seed weight, while five wild species surpassed the best races and G. arboreum in seed oil content, among them was G. harknessii. To breed simultaneously for seed oil content and seed weight, crosses between races of G. arboreum and wild species of Gossypium seem to be promising.     

The breeding of hybrid varieties and the production of hybrid seed in spinach

In spinach the breeding of hybrid varieties is attractive because this may result in a heterosis and/or a transgressive effect. Resistance to downy mildew [Peronospora spinaciae (Mont.) de By] and against mosaic (Cucumis virus 1) can be combined rather easily, since in both cases the resistance depends on one dominant gene. Besides a hybrid variety excludes the growing of later generations.However, a careful removal of all pollen-producing plants demands so much labour that a production of hybrid seed on a commercial scale involves great difficulties. The creation of an entirely female variety would be a solution for this problem. An outline has been given of the way in which such a variety can be developed, starting from purely female and from intersexual plants.It is possible to simplify the production of hybrid seed by using a round-seeded female parent and a prickly-seeded male parent. Moreover this will prevent errors: all plants can then be harvested and threshed at the same time and in cleaning the prickly seed can be separated mechanically from the round-seeded commercial seed. The use of a prickly-seeded male parent will be an extra check on the possible growing of later generations by others.     

Inheritance in seed size of alfalfa: Quantitative analysis and response to selection

Seed size in alfalfa (Medicago saliva L.) has been positively correlated with seedling vigour and early growth, but there were few published reports on inheritance or selection for this trait. The objective of this research was to estimate components of genetic variance for inheritance of alfalfa seed size and determine the most efficient selection method. Components of genetic variance were estimated on seed and pollen plants of ‘BIC-7-WH’ and their progeny arranged in a North Carolina Design II mating design under controlled environmental conditions. Three selection methods, differing in parental control and selection pressure, were used to determine selection response. The seed parent genotype had a major role in determining alfalfa seed size, but the genotype of the seed had no influence. For genetic studies, pollen and seed parent effects on seed size should be measured on seed harvested from progeny plants. Seed size was controlled by additive and non-additive components of genetic variance. Heritability for seed size was 41.3%. Selection for seed size was effective and a significant shift for larger and smaller seed was attained after one cycle of selection.     

Combining ability of seed vigor and seed yield in soybean

Studies have shown no consensus in relationships between seed yield and vigor in soybean [Glycine max (L.) Merrill]. The lack of information regarding the inheritance of seed vigor prompted this study to determine the types of gene action and combining ability estimates for seed vigor and its related traits. Five high and six low seed vigor soybean genotypes were crossed in a diallel, and selfed to produce 55 F₂ progenies, which were examined, along with the parents, for seed vigor, yield, and seed weight. Significant genotype and environment effects were found for seed vigor and yield. General combining ability (GCA) effects for seed vigor and seed yield were significant (p≤ 0.01) and larger than specific combining ability (SCA) effects. Significant GCA and SCA effects were found for seed weight, indicating that both additive and non additive genetic effects were involved in conditioning seed weight. The ratios of mean square, 2GCA / (2GCA+SCA), were 0.96 for seed vigor and 0.93 for seed yield. These ratios indicated that additive gene effects were more important than non additive gene effects for seed vigor and seed yield in these crosses. Mean seed vigor(83.8%), as determined by accelerated aging germination, and mean seed yield (2,155 kg ha^-1)in high vigor × high vigor crosses were higher than the high vigor × low vigor and low vigor × low vigor crosses. Mean percent accelerated aging germination rates in F₂ populations from diallel crosses were significantly related to mid-parent seed vigor(r² = 0.52^**) and midparent seed size (r² = 0.31^**). These results indicated that levels of seed vigor can be improved through breeding, while maintaining high yields because of the predominance of GCA effects in both seed vigor and seed yield. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mapping and analysis of QTLs related to seed length and seed width in Glycine max

Both seed length and seed width are important traits for soybean yield. In the present study, 89 Quantitative trait loci (QTLs) of seed length and 65 QTLs of seed width were collected from published papers and our study. QTLs in this study were evaluated by the soymap2, then totally 23 consensus QTLs were located on 17 linkage groups (LGs) through the meta‐analysis. The minimum confidence interval was 0.28 cM and the mean phenotypic variance (R²) was ranged from 5.33% to 23.36%. To optimize these QTLs based on statistic analysis, overview method was further used to narrow down CI, the number of QTLs was narrowed down to 84. Furthermore, 2,750 candidate genes were screened from the consensus QTL intervals by informatics, a total of 37 genes were found to be associated with seed size. All results could lay a foundation for MAS (Molecular Assisted Selection) and gene cloning.     

Major flowering time gene and polygene effects on chickpea seed weight

The effect of the major flowering gene (PPD) on seed weight of chickpea was studied on 450 F₃ families from reciprocal crosses between a small‐seeded, early‐flowering (PPD/PPD) type and a large‐seeded, late flowering (PPD/PPD) cultivar. F₄ progeny tests were carried out to determine the PPD genotypes of each individual F₃. The effects of the PPD gene and the polygenes on mean seed weight were both significant. Genetic correlations between time to flowering and seed weight were positive and relatively high, suggesting that in certain genetic backgrounds it might be difficult to breed early‐flowering cultivars without compromising seed weight.     

Use of immature seed germination and single seed descent for rapid genetic gains in pigeonpea

Long duration required for generation advancement in pigeonpea [Cajanus cajan (L.) Millsp] is one of the major bottlenecks in realizing rapid genetic gains. Therefore, a technology for rapid generation turnover is warranted to facilitate the development of new cultivars and recombinant inbred lines. Breeding of early‐maturing cultivars has now opened up the possibility of rapid generation advance (RGA) in this crop. This paper reports the development of an RGA technology that integrates the germination of immature seeds with single seed descent method of breeding. The results showed that immature 35‐day‐old seeds can be used successfully to turn over a generation of pigeonpea with 100% seed germination. These way 3/4 successive generations can be grown within a year. The methodology presented in this study will accelerate the breeding process for breeding cultivars and develop rapidly the materials required for genomics research in pigeonpea.     

Heat stress during seed development affects forage brassica (Brassica napus L.) seed quality

In two consecutive seasons, forage rape (Brassica napus L.) plants were exposed to short periods (240°C hr) of heat stress (30°C day/25°C night) during seed filling (80% seed moisture content = S1), at physiological maturity (50% seed moisture content = S2) and at both S1 plus S2 (=S3) in a Biotron before being returned to the field until seed harvest. Seeds were hand harvested at 14% seed moisture content and their quality assessed by measuring germination, seed vigour (using the accelerated ageing and conductivity tests) and seed mass (as determined by thousand seed weight). Heat stress at both S1 and S2 caused a small (<10%) but significant reduction in germination in both seasons. There was a significant heat stress timing interaction in the first but not the second season. Reductions in germination were a result of increased abnormal seedling production not seed death. All three heat stress treatments significantly reduced seed vigour, with S3>S2>S1. Seed mass was reduced by heat stress at S1 but not at S2. Variable seed vigour in high‐germinating New Zealand‐produced forage rapeseed lots is most likely explained by short periods of heat stress during seed development.     

A source of resistance to seed shattering in kleingrass,Panicum coloratum L.

Summary Seed of kleingrass, P. coloratum, ripen nonuniformly and shatter readily at maturity. Consequently, it is difficult to maximize both seed quality and yield. A source of resistance to seed shattering is needed. In this investigation, two kleingrass populations, the cultivar Selection-75, and an introduction from South Africa, PI 410177, were evaluated for seed shattering during three seed production seasons. Individual inflorescences from field-grown plants were enclosed in seed traps and all shattered seed was collected at weekly intervals until 49 days after anthesis. Although there were seasonal differences, PI 410177 always shattered seed at a slower rate than Selection-75 in each of the three seasons. Averaged over all seasons Selection-75 had shattered 74% of its seed by 49 days after anthesis while PI 410177 shattered only 37%. A separate greenhouse-field experiment demonstrated that seasonal differences in seed shattering are primarily the result of varying weather conditions during the period of seed production. PI 410177 is the first reported source of resistance to seed shattering in P. coloratum.     

Problems related to seed production in the African region

Improved seeds can make a substantial contribution to agricultural productivity in African countries. Seeds are one of the most important sources of innovation, particularly in resource-constrained small farm environments. They carry the genetic potential of the crops, determining the upper limit on yield and, therefore, the ultimate productivity of other inputs. Furthermore, new roles for seeds are rapidly recognized all over the world for the delivery systems of many innovative biotechnological products and as carriers of plant protection chemicals, biologicals and growth regulators. The seed sector development in Africa varies considerably among countries. Rather effective and diversified seed industries have slowly emerged and are operational in a few countries (e.g. Egypt, Kenya, Zimbabwe). In a growing number of other countries (e.g. Malawi, Zambia) the seed production and supply system has developed reasonably well in some areas for some crops. However, in most countries (e.g. Cameroon, Ethiopia, Ghana, Tanzania and Uganda) progress has been very limited in spite of investments and assistance. During the last decade a number of countries have undergone privatisation and/or seed market liberalisation as potential solutions to under-performance in the seed sector. However, it is not certain that this will produce a practical improvement and solve the problems of the poor rural majority of the population. In this paper the main problems related to the seed sector in Africa are discussed together with the possible roles of the private and public sectors in developing and maintaining an efficient and active seed industry. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of high oleic acid soybean on seed yield,protein and oil contents,and seed germination revealed by near‐isogeneic lines

Typical soybean oil is composed of palmitic, stearic, oleic, linoleic and linolenic acids. High oleic acid content in soybean seed is a key compositional trait that improves oxidative stability and increases oil functionality and shelf life. Using a marker‐assisted selection method, near‐isogenic lines (NILs) of G00‐3213 for the high oleic trait were developed and yield tested. These NILs have various combinations of FAD2‐1A and FAD2‐1B alleles that were derived from the same backcrossing populations. The results indicated that G00‐3213 NILs with both homozygous mutant FAD2‐1A and FAD2‐1B alleles produced an average of 788 g/kg oleic acid content. The results also demonstrated that possessing these mutant alleles did not cause a yield reduction. Furthermore, seed germination tests across 12 temperatures (12.8–32.0°C) showed that modified seed composition for oleic acid in general did not have a major impact on seed germination. However, there was a possible reduction in seed germination vigour when high oleic seeds are planted in cold soil. The mutant FAD2‐1A and FAD2‐1B alleles did not hinder either seed or plant development.     

Traditional maintenance breeding of landraces: 1. Data by crop

Examples of the methods of traditional maintenance breeding of several crops, cited in literature, are presented. It is concluded that, although crops are grown all over the world, only few examples are sufficiently described. Only for maize some reliable data are available. Three explanations for this small number are 1. the farmers are not aware of their knowledge of growing crops (including traditional maintenance breeding), 2. the interviewers and other scientists are not acquainted with this farmer's knowledge, or 3. most farmers do not actually perform traditional maintenance breeding, as they and their ancestors probably have experienced that traditional maintenance breeding does not result in a better crop. They must have thought that seed replacement was a better method to maintain the yielding capacity of their crops. This revised version was published online in July 2006 with corrections to the Cover Date.     

Can cultivars from participatory plant breeding improve seed provision to small-scale farmers?

Seed provision for small-scale farmers deals with multiple constraints. These include, on the supply side, high seed production costs and poor adaptedness of the cultivars, and on the demand side, anticyclical demand and low and variable sales. Approaches to improve seed provision to this sector of farmers have so far not been very successful. This paper discusses how well-adapted cultivars developed through participatory plant breeding (PPB) initiatives create new opportunities for production and distribution of quality seed. It reviews supply and demand-side issues, based on research and experiences with seed production. Given better adaptation of PPB-cultivars, the diffusion of seed of PPB initiatives should not be a major bottleneck. But constraints in the provision of quality seed from cultivars that are commonly used remain and need to be addressed. Major points of attention are cost-effective seed production and distribution, high information linked transaction costs, and appropriate seed production technology. Research on these issues is needed to understand farmers’ seed demand. At the same time, these issues need to be taken into account in new seed production initiatives that apply integrated approaches. Long term commitment by farmers to produce, distribute and use seeds is a condition. Even if seed production is not economically sustainable at household or organization level, farmer-based seed systems generate benefits to society as a whole that justify long term public investment to maintain them.     

Inheritance of siliqua orientation and seed coat colour in Brassica tournefortii

The inheritance of siliqua orientation and seed coat colour in Brassica tournefortii was investigated using four genotypes varying in these two characters. The F₁, F₂ and backcross generations of two crosses were used for studying the segregation pattern of the traits. The plants were classified for seed colour as having brown or yellow seeds and for siliqua orientation as having upright, semi‐spread or spread siliqua. Seed colour was found to be under monogenic control with brown being dominant over yellow. Siliqua orientation was under digenic polymeric gene action: upright siliqua was produced by the presence of two dominant genes and spread siliqua by two recessive genes. The absence of even a single dominant gene resulted in a third type of siliqua orientation, semi‐spread siliqua.