Henry S. Fleming

Bio: Henry S. Fleming is an academic researcher from University of Colorado Boulder. The author has an hindex of 1, co-authored 1 publications receiving 58 citations.

Cassava botany and physiology.

Abstract: Cassava is a perennial shrub of the family Euphorbiaceae, cultivated mainly for its starchy roots. It is one of the most important food staples in the tropics, where it is the fourth most important source of energy. On a worldwide basis it is ranked as the sixth most important source of calories in the human diet (FAO, 1999). Given the crop’s tolerance to poor soil and harsh climatic conditions, it is generally cultivated by small farmers as a subsistence crop in a diverse range of agricultural and food systems. Although cassava is a perennial crop, the storage roots can be harvested from 6 to 24 months after planting (MAP), depending on cultivar and the growing conditions (El-Sharkawy, 1993). In the humid lowland tropics the roots can be harvested after 6–7 months. In regions with prolonged periods of drought or cold, the farmers usually harvest after 18–24 months (Cock, 1984). Moreover, the roots can be left in the ground without harvesting for a long period of time, making it a very useful crop as a security against famine (Cardoso and Souza, 1999). Cassava can be propagated from either stem cuttings or sexual seed, but the former is the commonest practice. Propagation from true seed occurs under natural conditions and is widely used in breeding programmes. Plants from true seed take longer to become established, and they are smaller and less vigorous than plants from cuttings. The seedlings are genetically segregated into different types due to their reproduction by cross-pollination. If propagated by cuttings under favourable conditions, sprouting and adventitious rooting occur after 1 week.

Weeds and Domesticates: Evolution in the man-made habitat

Abstract: Weeds evolved, and are still evolving, within the man-made habitat in three principal ways: from colonizers through selection towards adaptation to continuous habitat disturbance; as derivatives of hybridization between wild and cultivated races of domestic species; and through selection towards re-establishing natural seed dispersal mechanisms in abandoned domesticates. Domesticates differ from weeds primarily in degree of dependency on man for survival. They evolved from wild food plants which were brought into cultivation. The process of domestication was initiated when man started to propagate plants in successive generations by means of seed or vegetative propagules. Phenotypic changes associated with planting and harvesting are species specific, and are brought about by natural selection under conditions of cultivation. Artificial selection by man during the domestication process is primarily responsible for subspecific variation in domestic species.

Microsatellite variation in cassava (Manihot esculenta, Euphorbiaceae) and its wild relatives: further evidence for a southern Amazonian origin of domestication.

Abstract: Genetic variation at five microsatellite loci was used to investigate the evolutionary and geographical origins of cassava (Manihot esculenta subsp. esculenta) and the population structure of cassava's wild relatives. Two hundred and twelve individuals were sampled, representing 20 crop accessions, 27 populations of cassava's closest wild relative (M. esculenta subsp. flabellifolia), and six populations of a potentially hybridizing species (M. pruinosa). Seventy-three alleles were observed across all loci and populations. These data indicate the following on cassava's origin: (1) genetic variation in the crop is a subset of that found in the wild M. esculenta subspecies, suggesting that cassava is derived solely from its conspecific wild relative. (2) Phenetic analyses group cassava with wild populations from the southern border of the Amazon basin, indicating this region as the likely site of domestication. (3) Manihot pruinosa, while closely related to M. esculenta (and possibly hybridizing with it where sympatric), is probably not a progenitor of the crop. Genetic differentiation among the wild populations is moderately high (F:(ST) = 0.42, rho(ST) = 0.54). This differentiation has probably arisen primarily through random genetic drift (rather than mutation) following recent population divergence.

Indigenous diversity of Cassava: Generation, maintenance, use and loss among the Amuesha, Peruvian upper Amazon

Abstract: For cassava (Manihot esculenta Euphorbiaceae), results from field collection, semistructured interviews, phenetic and cluster analyses, and Global Information Systems (G1S) indicate that cassava phenotypes vary with elevation and topography, but less with soils or pests and diseases. Amuesha women with a sense of tradition maintain many cassava varieties along with associated myths, songs, names and indigenous production. The shaman plays a key role in breeding new and maintaining traditional cassava germplasm, while the rest of the tribe nurtures cassava germplasm dynamics through collecting, trading, stealing, maintaining favored cassava varieties, and purging the less desirable. The future of cassava diversity is of concern to some Amuesha as production and market interests surmount more traditional attention to variety.

Traditional cassava-based foods: Survey of processing techniques

Abstract: Cassava (Manihot esculenta Crantz) is an important source of food in the tropics. Phillips (1974) estimated that by 1980 it would provide 37% of the calories consumed in Africa, 11% in Latin America and 6% in the Far East forming the staple diet of 500 million people. Total world production in 1978 was estimated to be over 119 mill tonnes, mainly distributed among Africa, South America and Southeast Asia (FAO, 1979). Production figures for the major cassava producing countries of the world for the years 1976-1978 are shown in Table 1. Most of the world production of cassava is used for human consumption in tropical countries, the other main uses being for animal feed and the starch industry. The latter 2 markets, however, accounted for only 6.5% of the world production in 1974 (Anonymous, 1977). To an even greater extent than other tuberous crops, cassava is primarily a carbohydrate source containing little protein and as such is often considered as an inferior food. However, in much of the world where severe malnutrition and even starvation exists, the populations suffer not only from protein deficiency but also carbohydrate deficiency. The production of cassava products using traditional methods of preparation goes far to alleviate the problem: indeed it is significant that in areas where cassava is extensively grown, severe famines seldom occur. There are many descriptions of the traditional methods used to prepare foods from the cassava root but most are oriented to particular areas of the world. There is no study of the subject on a worldwide basis. The present paper reviews the literature, bringing together information from all the major cassava-producing areas in order to focus attention on the diversity of the processing techniques and the wide variety of cassava-based foods and beverages that are produced. Cassava leaves are also used as a food particularly in Africa and they are a good supplementary source of proteins and vitamins (Terra, 1964). As such their role in the diet is very different from that of the cassava root and they will not be discussed here. However, there is a need for further studies on the value of cassava leaves in the diet.