This publication is the third of a series that aims to document progress made in the advanced use of rice genetic resources in Latin America. It focuses on the methodology of population improvement used in the context of the network formed by the Group for the Advanced Genetic Improvement of Rice (GRUMEGA, its Spanish acronym). The evolution of the activities that this group of institutions have carried out through the hard work and dedication of its researchers is closely followed, starting in the mid-1990s, when the group was formed to seek new alternatives to counteract the problems of developing new rice varieties. Such problems included the limited genetic progress made for quantitative traits like yield, and the scarce use of the immense genetic resources available for the crop. They led to the release of commercial varieties with very narrow genetic bases. The changing international scene brought new elements to the free exchange of germplasm, leaving almost on the sidelines, the progress made by countries that do not have breeding programmes to generate genetic variation for selection. While other factors could also be mentioned, these so far discussed were the most relevant for stimulating the group into seeking new ways.
With support from CIAT (Cali, Colombia), Embrapa Arroz e Feijão (Goiânia, Brazil) and CIRAD (Montpellier, France), a group of countries - that is, Argentina, Bolivia, Brazil, Chile, Colombia, Cuba, El Salvador, Uruguay and Venezuela - began, in 1996, its journey towards understanding and using rice population improvement through recurrent selection. As is generally known, this methodology was developed for allogamous crops, and the rice crop has had to be adapted for self-reproduction, using the recessive gene for male sterility.
During the early stages, how the method could be used to improve the rice crop was discussed, focusing on its advantages and disadvantages compared with more traditional methods used for improving rice. This methodology was found feasible as an additional strategy whereby countries could exploit the genetic resources available for the crop. Evaluations were then made of the populations that the institutions mentioned above had generated in their research on genetic improvement.
Greater use of genetic resources became reality in the countries when these developed their own populations based on those already created at CIAT, Embrapa Arroz e Feijão or CIRAD, or when they began studying local progenitors for creating local populations through crosses and recombination cycles.
When the management of populations with broad genetic bases was compared with that of the crosses and progenitors used by the national programmes, the next stage was to use population improvement. Some national programmes opted for using mass selection to improve the general level of the populations and fixing traits that were not of interest but were variable. Others sought to conduct evaluations in the second selfing generation (S0:2), and yet others decided to carry out more than one evaluation and begin in the generation of greatest segregation (S0), and then immediately advance the materials for selection in S0:2. Such focuses and methodological variants indicated that the countries quickly took ownership of the idea and of the materials, and are proceeding confidently towards reaching the specific objectives of their respective programmes.
The first chapters of this publication contain information that would permit those working with rice population improvement to discover alternatives for increasing the efficiency of their procedures for evaluation, selection and recombination, including the use of biotechnological tools. The middle chapters discuss the advances achieved by the countries. The publication ends by presenting specific research that served as thesis topics in Colombian and Brazilian universities.
FAO promotes the sustainable use of plant genetic resources within the context of the International Treaty on Plant Genetic Resources for Food and Agriculture. Article 6 of this International Treaty encourages the broadening of the genetic bases of crops. FAO also supports and closely follows all and any activity related to this theme, which is why it is associated with this publication.
Finally, two aspects characterize this work: first, Brazil released the worlds first variety for irrigated conditions to derive from a population improved through this methodology. It will be very soon followed by two more varieties, to be released in Bolivia and Chile, also deriving from populations subjected to population improvement. The second aspect refers to the importance that the countries have given to the use of genetic resources through population improvement. None of these activities, which were conducted by the national programmes of this group of countries, was financed externally, each having to obtain resources through adjusting the research portfolios of their own national programmes.
Deep gratitude is expressed to all those who are and were involved in the research and diffusion of the population improvement method, and to the national institutions that provided and continue to provide support to this idea, and take the results of this work to the farmers.
The international community, especially today, should seek to encourage the most efficient use of crop genetic resources. This publication provides examples of how this can be done. This technology is ready for transfer to any other rice-producing region and thus contribute to the worlds food security.