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The Portuguese maize bread (''broa'') manufactured from traditional maize landraces still plays an important economic and social role on Central and Northern rural communities of the country. However the traditional maize landraces agricultural systems are changing. Local maize landraces are in risk of disappearing because of the progressive adoption of hybrid varieties not suitable for bread production. These changes are contributing to a major loss of genetic diversity. An expedition took place in the Central region of Portugal (Beira Interior and Beira Litoral) with the purpose of collecting enduring maize landraces with technological ability for bread production and to access the possibility of establishing a participatory plant breeding and conservation program. A total of 51 different maize landraces and 175 other varieties of associated crops were collected. Maize landraces showed to maintain high diversity and potential for improvement. The production relayed on small farms with polycrop, quality oriented, sustainable systems. A participatory plant breeding and conservation program would be possible on this region with the proviso that local authorities would be involved. This program would allow a higher valuation of these maize populations, contributing to halt the current loss of these unique Portuguese maize landraces.

Maize ear fasciationKnowledge of the genes affecting maize ear inflorescence may lead to better grain yield modeling. Maize ear fasciation, defined as abnormal flattened ears with high kernel row number, is a quantitative trait widely present in Portuguese maize landraces.Material and MethodsUsing a segregating population derived from an ear fasciation contrasting cross (consisting of 149 F2:3 families) we established a two location field trial using a complete randomized block design. Correlations and heritabilities for several ear fasciation-related traits and yield were determined. Quantitative Trait Loci (QTL) involved in the inheritance of those traits were identified and candidate genes for these QTL proposed.Results and DiscussionEar fasciation broad-sense heritability was 0.73. Highly significant correlations were found between ear fasciation and some ear and cob diameters and row number traits. For the 23 yield and ear fasciation-related traits, 65 QTL were identified, out of which 11 were detected in both environments, while for the three principal components, five to six QTL were detected per environment. Detected QTL were distributed across 17 genomic regions and explained individually, 8.7% to 22.4% of the individual traits or principal components phenotypic variance. Several candidate genes for these QTL regions were proposed, such as bearded-ear1, branched silkless1, compact plant1, ramosa2, ramosa3, tasselseed4 and terminal ear1. However, many QTL mapped to regions without known candidate genes, indicating potential chromosomal regions not yet targeted for maize ear traits selection.ConclusionsPortuguese maize germplasm represents a valuable source of genes or allelic variants for yield improvement and elucidation of the genetic basis of ear fasciation traits. Future studies should focus on fine mapping of the identified genomic regions with the aim of map-based cloning.

Natural, and in particular, artificial (human) selection may pose a danger to the existing crop genetic diversity. Nevertheless, on-farm breeding systems seem to achieve phenotypic improvements even though preserving variability. Using SSR markers, we analysed several selection cycles, over a 20 years period, of a Portuguese on-farm participatory maize OPV-'Pigarro' breeding project. No significant differences in allelic richness (N ar ), observed heterozygosity (H O ), expected heterozygosity (or gene diversity; H E ) or inbreeding coefficient (f) were detected among the selection cycles. 58 out of 107 alleles were common to all the selection cycles studied. The analysis of molecular variance showed that the variation among selection cycles represented only 7% of the total molecular variation. However, the number of private alleles varied among the selection cycles, being the highest detected at the beginning of the selection project. These findings demonstrate that an allele flow took place during the on-farm selection process of 'Pigarro' but the level of genetic diversity was not significantly influenced. Since interesting phenotypic improvements were also achieved, on-farm breeding projects, like this one, should be valued as a way to preserve unique Portuguese maize landraces in risk of disappearing.

In 1984, Pêgo started, with the CIMMYT support, an on-farm participatory maize breeding (PMB) project at the Portuguese Sousa Valley region (VASO). VASO was intended to answer the needs of small farmers (e.g., yield, bread making quality, ability for polycropping systems). During 20 years of PMB at VASO, mass (MS) and S2 recurrent selection (S2RS) were applied on the maize landrace 'Pigarro'. Morphological (e.g., ear length and fasciation level) and yield evaluations were conducted in Portugal (2-3 locations in 2 years) and in USA (4 locations in one year) using samples from original population, six MS cycles and three S2RS cycles. North American Populations (BS21, BS22, TEPR-EC6) were also included as checks. ANOVA comparisons and regression analyses on the rate of direct response to selection were performed. Response to MS for Iowa showed significant decrease in stalk lodging, while in Portugal ear length significantly decreased, whereas ear diameter, kernel-row number, and fasciation level significantly increased. Selection also significantly increased days-to-silk and anthesis in Portugal. Response to S2RS in Portugal significantly increased days-to-silk, uniformity, and cob/ear weight ratio. These results showed that the methods used by farmer and breeder were not effective for significant yield increase, but the ear size increased significantly for MS and showed a positive tendency for S2RS. Adaptation to farmer needs was maintained for the last cycles of selection. Keywords Fasciation Á Mass and recurrent selection Á 'Pigarro' Á Participatory maize breeding Á Open pollinated variety Abbreviations NUMI Maize Breeding Station (Núcleo de Melhoramento de Milho) OPV Open-pollinated variety PMB Participatory maize breeding VASO Sousa Valley,