Thirty Years of Cassava Breeding for Productivity—Biological and Social Factors for Success

Abstract

to Asia in the early 1980s in the form of an applied breeding program in close collaboration with national The Centro Internacional de Agricultura Tropical (CIAT, headprograms. The Department of Agriculture (Thailand) quartered in Colombia) established a cassava (Manihot esculenta and CIAT established a collaborative cassava breeding Crantz) breeding program in the beginning of the 1970s with the aim program that distributed the advanced breeding materiof extending the Green Revolution success to less privileged sectors als to many national programs in Asia. of the tropical populations. The initial decade was mainly dedicated to the collection of germplasm and generation of basic breeding mate-The goal was defined as the establishment of a cassava rials. The later decades were devoted to applied breeding in collaborabreeding program with a global perspective that would tion with international and national programs in Latin America, Asia, generate economic benefits targeted to the less priviand Africa. This paper focuses on the basic breeding at CIAT/Colombia leged in the rural sector. During the whole period of (CIAT/HQ), applied breeding at CIAT/Thailand (CIAT/Thai), and development of the program, the following operating distribution and selection of improved materials with many collaboraprinciples or processes were closely adhered to: (i) estors in Asia. Fresh root yield of populations was improved by Ͼ100% tablishment of breeding methodology; (ii) generation of and root dry matter content by Ͼ20%. The national program collaborauseful breeding materials; (iii) distribution of advanced tors used these populations to develop many improved cultivars in breeding materials to national programs; (iv) establishmany countries. The biological factors considered as critical for this ment of competent national cassava breeding programs; successful breeding effort were as follows: inclusion of a broad base (v) development of improved cultivars; and (vi) dissemiof genetic variability obtained in the center of crop origin and diversifination of cultivars. cation; evaluation of breeding materials under diverse environmental conditions including high stress environments; and a clear understand-Within these procedures there were three distinct ing of the different operational principles at different stages of breed-technical phases performed under specific institutional ing advancement, as illustrated by the emphasis on harvest index in arrangements, each of which was critical to accomplishselection within populations and on biomass in population building. ing our goals: first, germplasm collection and evaluation, The understanding of crop germplasm being a common heritage and which formed the most important part of the basic the determination of agricultural scientists to use this for the welfare breeding at CIAT headquarters in Colombia; second, of the neediest people were the social factors for the overall success.

Yield traits as selection indices in seedling populations of cassava

“…When seedlings were 20 to 25 cm tall, they were transplanted to a well-prepared seedbed in the field, in Palmira, Colombia. Palmira is located at lat 3 0 06' N, long 76 0 32' W and 965 m asl; has an annual temperature of 24 0 C with clay soil texture (Jaramillo et al 2005, Kawano 2003. Seedlings were planted on ridges 1.5 m apart, with spacing of 0.6 m between plants.…”

Comparison of methods for phenotypic stability analysis of cassava (Manihot esculenta Crantz) genotypes for yield and storage root dry matter content

“…Cassava (Manihot esculenta Crantz) is a rich source of carbohydrates in the diet of millions of people in the developing countries that is cultivated under different edaphic and climatic conditions throughout the world, because of its efficient carbohydrate production (Kawano, 2003). As a consequence of its diverse cropping conditions, cassava shows a strong and significant genotype x environment (G x E) interaction effect (Fukuda, 1996;Kvitschal et al, 2007), which makes selection difficult.…”

Somatic embryogenesis in cassava genotypes from the northeast of Brazil

“…The new technologies for gene transfer are opening up new possibilities to generate improved cassava genotypes by integrating desired traits into farmer preferred cultivars; the ability to transfer new genetic materials into the cassava genome is essential if the crop is to fully benefit from major advances in plant biology (Kawano, 2003). Siritunga et al (2004) provided the first demonstration that gene transfer techniques can be used to develop cassava varieties with useful agronomic traits.…”