VARYING IMPACT OF BREEDING ACTIVITIES IN DIFFERENT ECOSYSTEMS AND IN DIFFERENT REGIONS

The number of varieties released is an indicator of the impact of breeding activities in different ecosystems and regions; another partial indicator is the increase in production and productivity over a period of time (Table 12). In Asia, the countries with most of the area (>50%) under rice in the irrigated ecosystem are: Pakistan (100%), Republic of Korea (99%), Japan (99%), China (92.7%), Sri Lanka (77%), Indonesia (72%), Democratic People’s Republic of Korea (66%), Philippines (61%) and Viet Nam (53%). Overall, 56 percent of the total rice area in Asia is under irrigated ecosystems.

TABLE 12
Area and productivity (by ecosystem) in different countries of Asia

Thailand, Nepal and Myanmar are the countries in Asia with greatest area in rainfed shallow lowlands. The shallow lowland ecosystem occupies 72, 62 and 52 percent of the total rice area in these countries. Major flood-prone areas occur in Bhutan (42%), Bangladesh (24%), Viet Nam (16%), Myanmar (14%) and Nepal (13%). The greatest upland areas are found in Myanmar (14.9%), India (14.6%), Indonesia (13.8%), Democratic People’s Republic of Korea (13.5%) and Thailand (11%).

The production potential and major constraints of the various ecosystems in West Africa are given in Table 13. The greatest rice area in West Africa is under humid or sub-humid uplands (40%), followed by rainfed lowlands (38%). Very little area (around 5% each) is under irrigated, mangrove swamp and deep-water ecosystems. Maximum actual productivity and potential productivity are achieved in irrigated ecosystems, followed by shallow lowland ecosystems.

TABLE 13
Production potential and major constraints to rice production across the major rice-producing ecosystems in West Africa

The percentage share of modern semi-dwarf varieties in various ecosystems in Latin America and the Caribbean is given in Table 14. Modern varieties occupy 97.6 percent of the irrigated ecosystem and 71.7 percent of the rainfed lowland ecosystem, contributing 98.3 percent and 76.7 percent to production. In upland ecosystems, modern semi-dwarf varieties account for between 18 and 31 percent and contribute between 24 and 30 percent to total production. The impact of modern semi-dwarf varieties has been high in the irrigated ecosystem, whereas in the upland ecosystem it has been very low.

TABLE 14
Percentage share of modern semi-dwarf rice varieties in rice production and area in Latin America and the Caribbean, 1966-1995

The coverage of high-yielding modern varieties in various ecosystems in Bangladesh is given in Table 15. Coverage under high-yielding varieties has steadily increased in all ecosystems. No high-yielding variety has been developed to date for deep water. Of the 10 Mha of rice area in Bangladesh, about half is covered by modern high-yielding varieties (HYVs). In boro (winter season), coverage by HYVs is about 90 percent; in transplanted aman (rainy season), coverage is around 50 percent; in aus (pre-rainy season), coverage is 21 percent; under deep-water ecosystems, coverage is practically zero.

TABLE 15
Rice area covered by high-yielding modern varieties in Bangladesh

Table 16 presents data on the coverage of HYVs in the various ecosystems in Latin America and the Caribbean. The impact of breeding activities varies greatly between ecosystems; the greatest progress has been made in irrigated ecosystems, followed by shallow lowlands, rainfed uplands and, finally, deep-water ecologies. Some of the major factors responsible for this varying impact are:

• the relative decrease in allocation of funds and human resources, combined with the lack of requisite infrastructural facilities for harsher environments and a general lack of attention;

• the comparatively limited genetic variability available for improvement of varieties for harsher ecosystems;

• numerous physical and biological constraints;

• the below optimal standard of crop management in harsh environments; and

• the lack of private initiative and research and development efforts for harsh environments.

TABLE 16

Modern semi-dwarf varieties (MSV) in production and area implicit yield, Latin America and the Caribbean (LAC), 1966-1995