Old tools as new support for on farm conservation of different types of maize

A germplasm collection should represent the diversity of the target species and the gene pools associated with it. However, it is critical to establish collection plans which ensure such representativeness. At times it is difficult to identify the best strategy for collecting domesticated species that are conserved in situ/on farm, since, in general, the magnitude of the diversity existing in a geographical area was hitherto unknown. The Diversity Census methodology was developed for previous diagnosis of the diversity of Zea mays subsp. mays L., conserved by farmers in two municipalities in the far western region of the state of Santa Catarina, southern Brazil. The Diversity Census database allowed for the identification of the best strategy to collect different types of maize landraces. Thus, tests were carried out using two methods described for Core Collections (Modified Random Sampling and Maximization) and a third statistical method for random sampling, stratified by farm area. The Maximization method enabled the capture of all the morphological variation of the traits evaluated in the Diversity Census from the smallest sample size. The relevance of this result is the feasibility of adapting the Core Collection strategy in order to plan more efficient expeditions to collect maize landraces conserved in microregions. Such planning allows for organizing the collection work efficiently, reducing costs, simplifying the work of characterization and helping to plan integrated strategies of in situ/on fam conservation.

Old tools as new support for on farm conservation of different types of maize

A germplasm collection should represent the diversity of the target species and the gene pools associated with it. However, it is critical to establish collection plans which ensure such representativeness. At times it is difficult to identify the best strategy for collecting domesticated species that are conserved in situ/on farm, since, in general, the magnitude of the diversity existing in a geographical area was hitherto unknown. The Diversity Census methodology was developed for previous diagnosis of the diversity of Zea mays subsp. mays L., conserved by farmers in two municipalities in the far western region of the state of Santa Catarina, southern Brazil. The Diversity Census database allowed for the identification of the best strategy to collect different types of maize landraces. Thus, tests were carried out using two methods described for Core Collections (Modified Random Sampling and Maximization) and a third statistical method for random sampling, stratified by farm area. The Maximization method enabled the capture of all the morphological variation of the traits evaluated in the Diversity Census from the smallest sample size. The relevance of this result is the feasibility of adapting the Core Collection strategy in order to plan more efficient expeditions to collect maize landraces conserved in microregions. Such planning allows for organizing the collection work efficiently, reducing costs, simplifying the work of characterization and helping to plan integrated strategies of in situ/on fam conservation.(AU)

Genetic variability for carotenoid content of grains in a composite maize population

Local maize (Zea mays L.) varieties are cultivated by small-scale farmers in western Santa Catarina (SC) State, in southern Brazil. These small areas frequently present many problems related to biotic and non-biotic stresses, which have limited the economic output and income of the farmers. Production from local varieties for human consumption would be an alternative way of improving income and stimulating on farm conservation. The genetic variability of the total carotenoid content (TCC) of kernels in a local maize population was evaluated for their economic exploitation potential as biofortified food. Two independent samples of 96 half-sib families (HSF) plus four checks were evaluated in two groups of experiments in western SC and each one was carried out in two environments. They were set out in a 10 × 10 partially balanced lattice with three replications per location; plots consisted of one row, 5.0 m long with 1.0 m between rows. TCC ranged from 11 to 23 µg g-1, averaging 16 µg g-1 in the pooled analysis over the two sets. The local composite population exhibited genetic variability in order to increase the TCC of grains in the second cycle of selection by the convergent-divergent scheme.

Genetic variability for carotenoid content of grains in a composite maize population

Local maize (Zea mays L.) varieties are cultivated by small-scale farmers in western Santa Catarina (SC) State, in southern Brazil. These small areas frequently present many problems related to biotic and non-biotic stresses, which have limited the economic output and income of the farmers. Production from local varieties for human consumption would be an alternative way of improving income and stimulating on farm conservation. The genetic variability of the total carotenoid content (TCC) of kernels in a local maize population was evaluated for their economic exploitation potential as biofortified food. Two independent samples of 96 half-sib families (HSF) plus four checks were evaluated in two groups of experiments in western SC and each one was carried out in two environments. They were set out in a 10 × 10 partially balanced lattice with three replications per location; plots consisted of one row, 5.0 m long with 1.0 m between rows. TCC ranged from 11 to 23 µg g-1, averaging 16 µg g-1 in the pooled analysis over the two sets. The local composite population exhibited genetic variability in order to increase the TCC of grains in the second cycle of selection by the convergent-divergent scheme.(AU)