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agro-ecological zones, cropping systems and agro-diversity

5.1 Agro-ecological regions

According to Panabokke (1996), “An agro-ecological region represents a particular combination of the natural characteristics of climate, relief and soil which tends to find expression agriculturally in particular farming system”. The country has been divided into 24 Agro-Ecological Regions (AER) to meet the requirements of regional specialisation of crops, research and development. The agricultural seasons, which correspond to the Southwest and Northeast monsoon, are called Yala and Maha respectively. The discussion on the crops grown in different AER, is based upon the work of C.R. Panabokke (1996).

5.1.i Demarcation of the country on the basis of elevation

The variation in elevation is an important agro-ecological feature, which forms the basis of land divisions in the into following zones:

Low-countryRegions below 300 m.
Most of the dry zone falls in this category
Mid-countryRegions lying at 300–600 m.
It includes wet and intermediate zones.
Up-countryRegion lying above 900 m.
Wet and intermediate zones fall into this category
Coastal plainsCoastal plains, flood plains, and sand dunes and beaches.

5.1.ii Demarcation on the basis of rainfall pattern and soils

A. Wet zone: This zone was divided into three categories as described below have unique ecological characteristics that provide specific advantage to selected crops and forest. A depiction of landscaping of rice-paddies, on lowland, and home and tea gardens on gentle slopes; and stepper slopes further up covered with forests is presented in Figure 4.

Figure 4

Figure 4

  1. Up-country wet zone: The land use in wet zone areas was classified as high country tea plantations, temperate horticultural tree crops and vegetables. The steep hilly terrain above 5 000 m elevation and 60 percent slopes in first aers is to be utilised for conservation forestry and in the remain two categories for conservation as well as fuel-wood plantations.

  2. Mid-country wet zone: This zone also was divided into three categories. The land use in vogue in first category is the traditional Kandyan Forest Gardens. The dry period from mid-January to mid-April had significant relationship with flowering of spice and beverage crops. The regions offered excellent agro-ecological conditions for tea plantations, spice crops like cloves, nutmeg and cardamom, fruit crops of avocado, durian, arecanut, breadfruit, jack fruit (jak), kitul, coffee, banana, black pepper, yams and other tuber crops. In addition, the paddy cultivation, in the valleys or on terraced slopes. The paddy cultivation provided high sustainable yields. The slopes above 50 percent were recommended for conservation forestry.

  3. Low-country wet zone: This zone is divided into four aers. First two aers are located near Marawaka and Avissawela in South-central region. The land use is suitable for rubber and low country tea plantations. The home gardens grow horticultural tree crops, rambuttan, mangosteen, kitul, pineapple and banana. The yields are moderate. Third is located in Matara, Galle and Kegalle Districts. The land use here is in the form as low-country tea and rubber plantations and home garden complex.

    The horticultural tree crops are coconut, rubber, coffee, banana and pepper. The paddy yields are moderately high and sustainable Galle and Matara have very productive cinnamon plantations.

    The fourth category AER in the wet zone lies near the coastal areas of Matara to Negumbo. The drainage in this region is poor. The Figure 5 shows the location of rice paddies in lowland and home garden and plantation crops in the slopes of the highland.

Figure 5

Figure 5

B. Intermediate zone

This zone is a demarcated into up, mid and low-country region. They are located between Matara and Tangalla in the South and cover parts of Monaragala, Badulla, Kurunegalla districts and coastal areas lying between Negumbo and Battalu Oya.

In the up-country intermediate region the terrain conditions vary from mountainous (Knuckles massif) to hills and rolling plains. The Southeastward located Ube basin with high rainfall and adequate sunshine is very productive for temperate horticultural and vegetable crops. The available irrigation during the period of May to September supports potato and vegetables cultivation in paddy fields. Tea plantations on slopes and cardamom under forest cover occur in this zone.

C. Low-country dry zone

The low-country areas in the North-central, Northwest, North and Southeast fall in this zone. The amount, duration and onset of the monsoon season is pronounced feature of this region (Panabokke, 1996). The zone receives rain during October–January from the N.E. monsoon. The undulating landforms show the highland-lowland feature. Chena cultivation is practised on highland, marked by the mixed crop cultivation of coarse grains, grain legumes, oilseeds and vegetables rainfed paddy cultivation is done in low lands. As Figure 6 shows the arrangement of chena crops, homegarden, a village tank and forest on the undulating landform of high and low lands. In lowlands paddy cultivation, both rainfed and irrigated, is practised. This area has large numbers of village tanks, large reservoirs and river valley projects for canal irrigation, the foremost being the Mahaweli Ganga Development Scheme of 1970's.

In the coastal plains of wet and dry zones, coconut plantations dominate. In coastal arid-zones, groves of palmyra palm and wild date palms occur in addition to coconut.

Figure 6

Figure 6

5.2 Genetic diversity in crop plants and conservation practices

The availability of a wide range of agro-ecological conditions had supported the creation of an equally large spectrum of genetic diversity in crop plants. The continuous process of selection meeting the local needs had generated a large number of cultivars. Periodically, new crop plant species and cultivars were introduced from India. In addition, traders, new settles and the colonial governments introduced new crop plants from far-away countries.



5.2.i Agricultural crops

A brief account of the genetic diversity in the agricultural and plantation crops is presented in this section. Also the current threat to biodiversity in selected food crops is examined as relevant to gender roles in biodiversity management.

A. Paddy

Paddy has been the traditional crop of Sri Lanka, in cultivation for the last 2 500 years. A recent assessment reports the occurrence of around 2 800 cultivars, covering a wide range of adaptation to different soil and climatic conditions, resistance to pests and tolerance to iron toxicity. Certain cultivars were evolved for grain type, fragrance and cultural uses. The varieties ‘Kalu Meenneti’ were grown for its taste and medicinal value; Varieties ‘Pusparaga’ from Welimada area was fragrant. Mawee variety was grown during the Maha season and varieties Kirinaran, Kaluwee, Devaraddiri and Kahatawee were grown near Sinharaja wet zone. However, during the last two decades, new high-yielding varieties (HYV) were imported and these were also resistant to various pests and pathogens with improved response to fertiliser inputs. These varieties have by now gradually replaced the traditional cultivars. The indigenous rice varieties have dwindled to merely 5 percent of the paddy acreage. In the dry-zone area, the farmers used certain indigenous varieties, which could be grown on rainfed chenas. The varieties were known by a suffix ‘al’ added to the name such as, rath al, pol al, bible al, kohu al, avand al and others (Vitharana and Withanage, 1993). The biodiversity issues related to paddy crop are summed up in Box.2.

Box No.2.
Loss of genetic diversity in crop plants
Over the past two millennia, selection and periodic introductions evolved about 2,800 cultivars of rice. These varieties adapted to withstand drought, floods, salinity, low temperature conditions and high iron contents. A few of them had qualities like fragrance (var. Pusparaga), good taste and others, food texture and medicinal properties (var. Kalu meenneti). Some varieties were adapted to grow on chenas, known as ‘Al’ rice, e.g. Rath al, bible al, kohu al and others in the dry zone of south. (Vitarana and Withanage, 1993).
In her study, Wickramasinge (1996) reports: Biodiversity loss in Kelegama, Sri Lanka
The nature of biodiversity changes was highly visible in the course of research in Kelegama, during 1987–1989. Although the women interviewed were able to recall numerous locations where widely used plant varieties were once obtained, they were unable to find these varieties any more. In addition, the overall environmental degradation in these areas had inhibited the migration of seed-carriers like birds and animals. Fourteen varieties of root crops, used during off-harvest seasons as substitutes for the staple diet of rice, are no longer available. Nearly 84 varieties of plants with medicinal and food values have been lost. Indigenous varieties of millet, cassava, wild rice, sesame, pumpkins, melons, cucumbers and herbs are no longer available. What is seen in the case of Sri Lanka is not only a transition from local cultivars to foreign ones, but also a transition from women's control over genetic resources to external gene pools managed by male-dominated sectors. The costs are the depletion of diversity and more expensive sceds and other materials”.
Grains of wild rice species, which occurred around cultivated areas, were also consumed in case of scarcities. The wild species being tolerant to water stress were able to survive a poor monsoon. The writer noticed a wild rice species, Oryza rufipogon Griffith, growing in the dried water channel of the paddy fields in the month of April, near Habarana, a dry zone area. The Maha paddy season was already over, the wild species was in the flowering stage, indicating a variant growth pattern, which is a useful genetic trait The introduction of high-yielding varieties of paddy has reduced the cultivation of traditional varieties to mere 5 percent of the total area. Some of the traditional varieties are being conserved under ex-situ conditions at the Plant Genetic Resource Centre and Rice Research and Development Institute.
A similar situation has come to exist for highland crops. Coarse grains like kurakkan (Finger millet, Eleusine coracana), meneri (Panicum miliaceum), thana (Foxtail millet, Setaria italica), Paspalum scrobiculatum, and thala (Sesamum indicum) have also shown reductions in cultivation area. These crops, scattered over a large dry zone area in the country, have not undergone much selection, hence possessed a large genetic base. Coarse grains are of high nutritional value, rich in protein and mineral contents, and their intake prevented malnutrition. The chena farmers believe that consumption of meneri and other millets are considered good for those who suffer from ailments like diabetes and high blood pressure.
Coarse grains have always been women's crops, and thus provided food security to the family. The declining area indicates a diminishing of women's traditional role in chena cultivation. One of the better methods of protection of the existing gene pool of these crops is to support the farm family's effort of in-situ on-farm conservation. This method is likely to succeed with a deliberate effort on part of the State by inducting appropriate post-harvest technologies, creating interest and market linkages in urban area. With increasing awareness of health foods among urban people, the coarse grain crops could find a profitable future in the growing network of supermarkets. The concerned state agencies could support women entrepreneurs from rural areas with required technologies and financial support. The coarse grain crops offer a system of unique genetic base, which should not be lost under the rising tide of high-yielding, high value monoculture food crops. Besides, the emerging dietary habits centred on rice are leading to increasing trends of nutritional imbalance.

B. Minor crops: millets

Cultivation of millets was very common on chena lands. Comparatively short growth periods, ability to withstand drought and high nutritive value have made millet cultivation an essential part of chena cultivation. The commonly grown millet species are given below:

Conservation practised is mainly as in-situ on-farm work. Here the millets have found special favour with women for their high nutritive value and ability to survive under drought conditions. The women in the household looked after the seed selection and storage. Millets in general are preferred food for their high nutritive value and therefore, fetch a good price. But there are not enough buyers to encourage growers. Since, millets are grown over a large area in the dry-zone chena cultivation crops have evolved a large genetic base with limited selection efforts by farmers.

5.3 Present efforts in conservation of agro-biodiversity

The Plant Genetic Resources Centre (PGRC) at Gannoruwa, Peradeniya, has, since its establishment a few years ago, collected and preserved propagative material of a large number of species from various agro-climatic zones of the country. The Plant Genetic Resource Centre, at Ganoruwa, is in the process of collecting the germplasm of agricultural crops. Some of the accessions as of March 1993 are given in Annex 4.

The Central Agricultural Research Institute at Gannoruwa and several similar research and breeding centres in the country also maintain accessions of selected species. Some of the accessions of crop groups as of March 1993 at the PGRC are given in Annex 5.

Besides these accessions of food crop species listed in Annex 5, PGRC collection has many other accessions of root and tuber crops, species and other economically important plants.

The ongoing efforts, which had a recent beginning, have been inadequate to marshall a fair representation of the vast pool of germplasm in the form of large number traditional cultivars scattered all over the country. In fact, farm families in remote areas might still be maintaining different genetic stocks of agricultural species. Many of these varieties were introduced in former times from neighbouring and far-away countries. Even in the absence deliberate efforts by the farmers, such varieties would have crossbred, especially those, which normally cross-pollinated. Therefore, genetic stock of traditional varieties of crop plants require not only efforts to conserve them under ex situ conditions but also to initiate simultaneous genetic studies to identify the useful gene complexes. Rural women can be seen as agricultural scientists who have a key role to play in a dual role of farmers and seed managers for selective breeding on the farm. These women thus could be seen as indigenous geneticists in local farming communities.

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