Maize Conservation Research Articles

Adoption of maize conservation tillage in Azuero, Panama

An aggressive research and validation program launched in 1984 in Azuero, Panama, yielded a recommendation advocating zero tillage for maize production. Ten years later, maize farmers in Azuero used three land preparation methods: conventional tillage, zero tillage, and minimum tillage (an adaptation of the zero tillage technology). This study aimed to quantify the adoption of zero and minimum tillage for maize in Azuero; identify factors influencing adoption of the different land preparation practices; and analyze the implications of the findings for future maize research and extension. Between 1985 and 1994, farmers in Region I of Azuero changed from conventional tillage to zero (33%) and minimum tillage (43%). In Regions II and III, most farmers still practiced conventional tillage in 1994, although 34% had switched to minimum tillage. Across regions, adoption of conservation tillage was motivated by potential cost savings rather than longer term considerations such as reduced soil erosion. The factors that limit adoption of conservation tillage vary by region. In Region I, adoption of conservation tillage is limited by land rental rather than ownership and by lack of conservation tillage planting equipment. In Regions II and III, lack of information about conservation tillage technology limits the probability of adoption. Future research should examine soil compaction, a key variable for understanding differences between the adoption of minimum and zero tillage. Another area that merits further research is the link between weeds and conservation tillage: several farmers reported using the technology to obtain better weed control. The long-term effects of conservation tillage should also be assessed. Extension in Regions II and III should seek to accelerate adoption of conservation tillage, particularly zero tillage. In Region I, extension should steer the change process from minimum to zero tillage.

In Situ conservation of maize in Mexico: Genetic diversity and Maize seed management in a traditional community

Results from a study of maize varieties and seed sources in a traditional community in Jalisco, Mexico, raise questions about the relationship between genetic erosion and the introduction of varieties. The relevance of models for in situ conservation of crop genetic resources based on geographical isolation of a community is discussed. The morphophenological diversity of local materials is shown to be enhanced by introductions of both improved cultivars and landraces from farmers in other communities. On the other hand, the geographical point of reference for defining “local” landrace is shown to be larger than the community itself. Farmers will classify seed obtained from other farmers in and outside the community as that of a local landrace if it resembles their own according to the phenotypic characteristics they use to distinguish varieties. Maize diversity in this community is then the result of a certain level of introduction of genetic material and not of geographical isolation.

Practical considerations for maintaining germplasm in maize

The main goals of genetic resource management are to acquire, maintain, distribute, characterize, regenerate, preserve, evaluate, and utilize the genetic diversity of crops and their wild relatives. The objectives of this study for ex-situ conservation of maize (Zea mays L.) are to review and describe: (1) practical regeneration methods that are based on population genetic theory; (2) practical problems encountered in choosing core subsets of a maize collection. Whenever possible, regeneration procedures should control the number of pollen parents (male gametes; through controlled hand pollination) and the number of female parent gametes (by harvesting equal numbers of kernels from each seed plant). When the number of pollen and seed parents are controlled during regeneration, the effective population size (Ne) is twice the size of the original population (N). Examples of practical methods for controlling the number of male and female parents are presented. The procedure involves random-paired plant crosses and taking equal numbers of seeds from each maize ear. To form a core subset, accessions of a maize race are subdivided through a stratified sampling procedure. Delineation of a core subset from a Tuxpeño racial collection is described as an example.