Introduction

The Ethiopian region is characterized by a wide range of agro-climatic conditions, which account for the enormous diversity of biological resources that exist in the country. Probably the most important of these resources is the immense genetic diversity of the various crop plants grown in the country.

The indigenous landraces of the crop plant species, their wild relatives and the wild and weedy species which form the basis of Ethiopia's plant genetic resources, are highly prized for their potential value as sources of important variations for crop improvement programmes.

Populations of these forms of plant species also represent sources having the greatest potential for genetic diversity and can therefore serve as invaluable means to fill the gaps that still exist in the available base of genetic diversity in the world collection of many major crop species. Among the most important traits which are believed to exist in these materials are earliness, disease and pest resistance, nutritional quality, resistance to drought and other stress conditions, and characteristics especially useful in low-input agriculture.

Scientists from many parts of the world have identified highly desirable genetic characteristics in relatively few germplasm collections of various crop species and they are currently being utilized intensively in a number of breeding programmes.

Introduction

Although spices are considered as minor crops their significance for Ethiopia can hardly be overestimated. Spices are needed every day in considerable amounts for the preparation of the main dish of the day.

Most of the spices needed in Ethiopia are grown as field or garden crops, although some grow in the wild. Classical spices are also used but have to be imported, mainly from India. The following 12 spices, which originated in Ethiopia or were introduced very long ago and are considered to be of importance, are dealt with in this chapter:

1. Capsicum annuum (red pepper); Amh.: berbere

2. Trigonella foenum-graecum (fenugreek); Amh.: abish

3. Nigella sativa (black cumin); Amh.: tikur azmud

4. Trachyspermum ammi (Ethiopian caraway); Amh.: nech azmud

5. Coriandrum sativum (coriander); Amh.: dimbilal

6. Aframomum korarima (false cardamom); Amh.: korarima

7. Cuminum cyminum (cumin); Amh.: kamun

8. Foeniculum vulgare (fennel)

9. Pimpinella anisum (anise); Amh. for both: insilal

10. Ruta chalepensis (rue); Amh.: tena-addam

11. Ocimum basilicum (basil); Amh.: basobila

12. Piper longum (Indian long pepper); Amh.: timiz

13. Rhamnus prinoides (buckthorn); Amh.: gesho

Although ‘gesho’ is not a typical spice, it is included in this list, since it is of extreme importance in the flavouring of beverages during their preparation (Jansen, 1981).

In a broader sense, shallots (Allium cepa) and garlic (A. sativum) can be considered as spices.

Introduction

Barley in Ethiopia is used for human food, home-made beverages and beer. Its straw is used for animal feed and mattresses. It is produced in the highlands at altitudes ranging from 1800 to 3300 m above sea level, where poor soil fertility, frost, waterlogging and moderate soil acidity are major problems. It occupies an area of about 0.85 million hectares out of a total crop land of 6.0 million hectares with a productivity of about 1.2 t/ha (Central Statistics Office, 1984). At high altitudes it may be the only crop grown, with or without oats; and among the small grains it is the earliest to become available for consumption at the end of the rainy season.

Barley is grown in the main rainy season of June–September (‘meher’) on sloping and better drained clay soils. Some barley is grown in the short rainy season (‘belg’) on bottom lands in some regions. A few areas also grow barley from October to January (‘bega’), sometimes with supplementary irrigation. Double cropping is a common practice in the major barley growing regions: barley–barley in ‘belg’ and ‘meher’ seasons in Shewa, Welo, Arsi, and Bale; barley–barley in ‘meher’ and ‘bega’ in Gojam; and barley–pulses in Gondar.

The level of management is traditional. Farmers use their own landraces in most cases. Application of inorganic fertilizers and use of insecticides and herbicides are fairly low. The landraces are tolerant to marginal soil conditions.

Introduction

Sorghum is one of the crop types for which Ethiopia has been credited as being a Vavilovian centre of origin or diversity (Harlan, 1969). In the different ecological zones of the country, germplasm resources representing the major and intermediate races of sorghum are found. In addition, the existence of wide variation in plant, grain, inflorescence and fruit characteristics in the Ethiopian sorghum germplasm is well documented (Gebrekidan, 1973; Gebrekidan & Kebede, 1977). Among the sorghum growing population in the rural areas, the importance of this crop is exemplified not only by its use as a staple food and for other purposes, but also in the folklore, songs and some of the local names by which the sorghum varieties are known.

As one of the leading traditional food cereals in Ethiopia, in terms of both total production and area, major research efforts have been directed towards the improvement and stabilization of sorghum yields. At a national level, sorghum improvement involves the manipulation of indigenous and introduced germplasm to develop adapted types for the various ecological zones. In crop improvement work the indigenous germplasm has been found invaluable (Gebrekidan, 1981).

Periodic sorghum germplasm collections made throughout the country have provided the sources of breeding material necessary for the sorghum improvement programme. In the high altitude areas the indigenous germplasm has often been the only adapted material suitable for use. From evaluations of germplasm collections, potential varieties have been identified.

Introduction

All our modern crops have been developed from wild plants. The domestication of a plant passes through stages from intensified usage of the wild plant to the development of a domesticate so dependent on Man that it cannot survive in the wild. All stages are seen in the crop complement of Ethiopia. There are many wild plants which are used for food, particularly in times of food shortage such as the period between seed sowing and harvest. It is hardly surprising that the majority of such plants are those used as leafy vegetables, followed by those with edible fruits, tubers or roots. Another example is the grass, Snowdenia polystachya (Fresen.) Pilg., whose seeds are collected and used in a similar way to teff. The following account includes only those that are related to domesticates. Examples of semi-domesticated plants are Avena abyssinica and Coccinia abyssinica, both of which are discussed further below. There are also wild plants now attracting attention as potential crops, for example Vernonia galamensis (Cass.) Less. (Perdue, 1988) and Cordeauxia edulis (Hemsl.) (Polhill & Thulin, 1989). Ethiopia also has fully domesticated endemic crops, the best known being teff, Eragrostis tef and ensete, Ensete ventricosum. For fully domesticated plants the wild species from which the crop developed has in some cases been identified; in others it seems to have disappeared after the plant was domesticated.

Both environmental degradation and modern agriculture are putting traditional crops and their wild relatives at risk.

Introduction

Plants which are utilized as fodder for livestock are confined to those which can provide maximum yields in animal production with minimum management inputs. Such plants are usually members of the families Gramineae and Leguminosae and are mainly herbs or subshrubs. In recent years leguminous shrub and tree species have been receiving increasing attention, particularly for small farmers in developing countries.

The Gramineae and Leguminosae are major sources of human nutrition as cereals and pulses while the by-products of these crops are major sources of nutrition for livestock. This report will be confined, however, to plants which are planted primarily as livestock fodder.

Ethiopia, as part of the African continent, shares many genera and species of grasses and legumes with the rest of the continent. However, its great variations in climate and relief and its heavily dissected landscape have provided the opportunity for further evolution of species and genotypes. About 64 species of legumes, mainly montane (10–11 per cent of the total), have been reported as probably being endemic to Ethiopia, while 30 species of grasses are endemic (Thulin, 1983).

African grasses are the main source of cultivated commercial grass species and cultivars in the tropics and subtropics worldwide and are almost all represented in Ethiopia. While Africa is not the major centre of diversity in legumes it is a major centre of diversity for such genera of fodder potential as Aeschynomene, Alysicarpus, Indigofera, Lablab, Lotononis, Macrotyloma, Neonotonia, Trifolium and Vigna.

Introduction

Proper evaluation of the very large germplasm collections now assembled for many crop species presents major problems. These arise principally from the effects of the environment on the expression of plant characteristics. For qualitative characteristics there is little difficulty as their expression is usually affected little by environment. Examples are seed coat and flower colour and colour pattern. A single evaluation is all that is required to characterize a set of materials for such characteristics.

It is, however, the quantitative characteristics, and these are of most interest to the breeder, that are especially intransigent as their expressions are always modified by environment to some degree, so that the separation of the contributions of genotype and environment to the phenotype requires special techniques.

Environment and genotype × environment interaction

The modification of plant characteristics by environment takes two forms. First, there is a general reduction or increase in expression of a character across all genotypes. Environmental features such as soil fertility, moisture availability, temperature and pathogens, pests and weeds may all affect plant characters in this way. The result is what is often termed ‘field variability’ and this will always occur in a single evaluation at a single location in a single season. It also occurs across locations and seasons.

Secondly, there is the situation where all genotypes are not affected equally by differences in environment, normally described as ‘genotype × environment (g × e) interaction’.

Introduction

The richness of Ethiopia's biological resources is well known. It has been mentioned by several scientists that the country exhibits an extraordinary genetic diversity in cereals such as barley (Hordeum vulgare), wheat (Triticum spp.), sorghum (Sorghum bicolor) and teff (Eragrostis tef), oil crops such as castor bean (Ricinus communis), sesame (Sesamum indicum), and other lesser known but potentially valuable species of plants. Eleven cultivated crop species have been identified as having their centre of diversity in Ethiopia (Zohary, 1970). Vavilov (1951) indicated that some 38 species are connected with Ethiopia as a primary or secondary gene centre.

Owing to the potential and uniqueness of the biological resources of this country, numerous exploration expeditions have been undertaken in the past. The earliest was probably the one made by Schimper in 1840, a year which appears to mark the beginning of botanical collecting in Ethiopia (Gentry, 1971). However, it was after the establishment of the Plant Genetic Resources Centre/Ethiopia (PGRC/E) that systematic collecting was launched on a large scale.

Agents of genetic erosion

The valuable genetic diversity in Ethiopian crop species, as well as in their related wild species, has been built up over the centuries by the natural selective forces of the environment and the farming community.

Introduction

The majority of the germplasm accessions maintained by the Plant Genetic Resources Centre/Ethiopia (PGRC/E) are landraces which have evolved under local conditions in the farmers' fields since time immemorial. Such gene pools are the reservoirs of variation which provide the raw material for crop improvement. Samples in the form of seeds or whole plants, representing the spectrum of genetic variation within cultivated species and their wild relatives, are currently being collected and maintained in seedbanks and field genebanks throughout the world (Frankel & Hawkes, 1975; Williams, 1984). Of fundamental importance in the management of these resources is the determination of the variation they represent. To this end, characterization of the various crop germplasm collections is undertaken by the multiplication, characterization and evaluation division of PGRC/E in close collaboration with the plant breeders.

In the past, characterization activities were limited in scope and greater attention was given to collection and conservation activities. During the last three or four years, however, the priorities have changed and now include the extension and intensification of characterization and evaluation work, as well as support for the utilization of germplasm. Highest priority has been given to the major economic crops (e.g. cereals, pulses and oil crops) with the aim of providing useful materials for the breeding programmes.

Crop germplasm multiplication and rejuvenation

Because of the earlier priorities, a systematic increase of the collected germplasm accessions did not start until 1982.

Plant genetic resources constitute the building blocks of all modern plant breeding. They form the raw material from which new varieties have been systematically bred to meet the growing need for more food. These traditional genepools are an invaluable asset to the welfare of mankind and should be preserved, both for current use and for posterity. Loss of genetic diversity is detrimental to crop improvement programmes. To prevent this loss countries in all parts of the world are endeavouring to conserve and utilize these precious materials. The plant genetic resources (PGR), thus, must be systematically collected, characterized, evaluated, documented and conserved, for effective utilization. This is all the more important, now, since agriculture is becoming more and more industrialized, thus leading to a narrowing of the genetic base, demanding genetic uniformity and causing vulnerability to pest and disease attacks, all of which pose high risks to sustainable agricultural production systems. The variability in landraces, and the primitive cultivars held by traditional farming societies, can provide the world with appropriate raw material to stop such unwanted processes. It is therefore essential to conserve it at all costs.

The urgency and the need to collect and conserve plant genetic wealth was advocated some three decades back by the Food and Agricultural Organization of the United Nations (FAO), and since the 1960s the network of activities in this context has spread considerably.

Introduction

Among the economic species of coffee grown in more than 50 countries in different parts of the world, Coffea arabica L. is the only tetraploid species of the genus. It contributes over 80 per cent of the world's coffee production. In many scientific reports Ethiopia is considered to be the centre of origin and diversification of coffee (Sylvain, 1958; Fernie, 1966; Food and Agriculture Organization, 1968; Carvalho et al., 1969; Ameha, 1980; Rodrigues, 1981; Worede, 1982; Watkins, 1985). The question of whether the south-west mountain moist evergreen forest, the farmer's field or the low altitude river banks is the primary habitat is not discussed here, although the issue is of primary interest to geneticists and breeders, for conservation purposes and in the search for primitive genes in the wild progenitors.

Arabica coffee is an evergreen shrub of variable size. The tree grows up to 14 m in height and about 2 m in width under forest strata and up to 6 m in height and about 12 m in width in canopy under farmers' holdings (a tree this size was observed in Wanago near Dilla in Sidamo administrative region). Naturally, it has a dominant central orthotropic stem and horizontally growing plagiotropic branches with pairs of secondary, tertiary, etc. branches originating from preceding branches in the hierarchy. The leaves are borne in opposite pairs along the side of the branches. The flowers emerge as inflorescences on all forms of lateral branches in each leaf axil of the nodes.

Introduction

Ethiopia is known as a centre of diversity and/or origin of numerous cultivated crop plant species. This was first recognized by N. I. Vavilov in the late 1920s and later confirmed by several other scientists. Vavilov (1951) indicated that some 38 crop plants have their centre of diversity in the Ethiopian region. Zohary (1970) mentioned 11 crop species which had their centre of diversity in Ethiopia. Primitive cultivars or landraces and wild relatives of some of the world's major crops are found in the country. Pulse crops form a significant portion of the available genetic resource base for plant breeding programmes.

In this chapter an attempt is made to describe the situation for the most important pulse crops cultivated in Ethiopia regarding their diversity and the germplasm kept in the national collection, and their conservation, evaluation and utilization.

Collection

Owing to the richness and potential of the biological resources of the country, numerous plant expeditions have been undertaken by scientists in the past. However, it was only after the establishment of the Plant Genetic Resources Centre/Ethiopia (PGRC/E) in 1976 that systematic collecting missions were launched. The total holding of pulse accessions by PGRC/E is about 4300.

The bulk of the germplasm was acquired from field collecting (ca. 2900) on the basis of a well defined strategy, and some was acquired through repatriation and acquisition from national and international sources.

Introduction

Hypotheses on crop development in Africa are long on theory and short on fact. Let me present my own ideas. Harlan & Stemler (1976) have presented a theory that sorghum developed in the southern Sudan–Chad region. My problem with that is the answer to the question ‘how’? It is true that as soon as Man began to sow the seeds of wild grasses, selection and sowing over the years would result in cultivated types being developed. That assumes that Man somehow learnt the idea of agriculture. Perhaps he did, but it is not clear how this happened in the rainfed savannahs. There were lots of grasses there anyway, and lots of grass seed. Why sow more? How would man have learnt to sow seed? How would he have distinguished between the masses of grass seedlings coming up with the rains and those which he had put in? By clearing a separate plot of land for sowing? That presumes the idea of agriculture. Having worked in the tropics for many years, I find this altogether too difficult to imagine.

It is more likely, to my mind, that agriculture was discovered along rivers and that the discovery was a rather rare event. One should always look at the possibility of the spread of the idea of agriculture from elsewhere before concluding that it had been discovered all over again. My scenario for the discovery of agriculture in a situation of this kind is presented below.

Introduction

Several publications have dealt with India's cultural contacts with western, central and south-east Asian countries, but little information is available on India's contacts with African countries (Asthana, 1976). This is understandable because little archaeological work has been done on Neolithic to Iron Age sites in Africa, compared with Asia. Even in India, where several Neolithic-Chalcolithic sites have been excavated, archaeologists have continued to look for some kind of west Asian similarity/influence in interpreting their findings. Thus, even (a) the finds of human skeletons showing Hamitic-negroid features associated with the Langhanag (Gujarat) microlithic culture (Sankalia, 1962); (b) terracotta head-rests discovered in Neolithic burials at Narsipur (ca. 1800 BC), Hammige, Hallur (ca. 1800 BC) and Paklihal in the Kaveri and Krishna basins, showing affinity with similar objects found in Africa and Egypt (Nagarajarao, 1975); and (c) archaeological finds of African crop plants (Vishnu-Mittre & Savithri, 1982) have been ignored. Evidences for indigenous origin(s) of few, or even several, Neolithic – Chalcolithic cultures of India have been recently discussed but with bitter controversy (Possehl, 1982). African millets were incorporated into the cropping system of Chalcolithic farming communities of India, and these may provide evidence of contacts between India and Ethiopia where agriculture was practised (ca. third millennium BC).