Pearl millet [Pennisetum glaucum (L.) R. Br.]
Pearl millet is a highly cross-pollinated (more than 85% outcrossing) diploid annual (2n=2x=14) with a large genome size (2450 Mbp). It is grown annually on more than 29 million ha in the arid and semi-arid tropical regions of Asia, Africa and Latin America.
India is the largest` producer of pearl millet in Asia, both in terms of area (about 9 million ha) and production (8.3 million tons) with an average productivity of 930 kg/ha during the past three years (Figure 1). From the early 1980s, the pearl millet area in India declined by 22%, but production increased by 36%, due to a 75% increase in productivity (from 530 kg/ha during 1981-1983 to 930 kg/ha during 2008-2010).
Figure 1. Three-year moving average for pearl millet area,
production and grain yield; and number of varieties/hybrids released
(3-year total) based on ICRISAT-bred material in India.
Since 1986, the year when WC-C75, the first ICRISAT-bred open-pollinated variety (OPV), was released for cultivation, 67 cultivars based on ICRISAT-bred germplasm (14 OPVs and 53 hybrids) have been released and notified in India. Among the OPVs, five were developed by ICRISAT and nine by NARS. Of the hybrids, five were developed by ICRISAT, and 31 by NARS based on ICRISAT-bred male-sterile lines. Seventeen hybrids developed by the private sector were also based on ICRISAT-bred male-sterile lines, or on selections made within these lines. Many other released and notified hybrids from the private sector, and several others marketed as truthfully labeled seeds, also involve some degree of ICRISAT-bred materials. The improved cultivars are grown on more than 4.5 million ha (of about 9 million ha), of which the OPVs cover only 0.6-0.8 million ha, with the remaining area cultivated with hybrids. This enormous hybrid cultivar diversity with improved productivity has not only contributed to increased productivity, but has also halted recurrence of downy mildew epidemics that were observed quite often during the 1970s and 80s.
Figure 2. Three-year moving average for pearl millet area,
production and grain yield; and number of varieties released
(3-year total) based on ICRISAT-bred material in West and Central
Besides the main rainy season crop, there is now increasing interest in pearl millet cultivation as an irrigated summer season crop in parts of India (Gujarat, Rajasthan and Uttar Pradesh) where a few hybrids that tolerate temperatures of 42°C and above during flowering, have given very high grain yields (4000-5000 kg/ha) in farmers’ fields. Germplasm and breeding lines with high temperature tolerance are now being identified to diversify the genetic base of parental lines to develop high-yielding hybrids adapted to such environments.
Western and Central Africa (WCA)
The West and Central African (WCA) region has the largest area under millets in Africa (16.8 million ha), of which more than 95% is pearl millet. Since 1982, the area of pearl millet in this region has doubled (from 7.8 to 16.0 million ha), and grain yield increased by 19% (from 740 to 880 kg/ha), contributing to the 143% increase in grain production (from 5.8 to 14.1 million tons) (Figure 2). Thus, most of the increase in pearl millet production in the region during this period has come from increases in cultivated area (4% per year), although there has been a small increase in productivity (0.7% per year). Across the six major pearl millet producing countries in WCA (Niger, Nigeria, Mali, Chad, Burkina Faso and Senegal), the productivity increases during this period have varied from 0.2% per year in Chad and Niger to 1.6% per year in Burkina Faso, except for Nigeria where yields actually decreased from 1570 kg/ha in 1982 to 960 kg/ha in 1992, and then increased sharply to 1610 kg/ha by 2008.
Pearl millet breeding in WCA has concentrated on the development of open-pollinated varieties (OPVs). Hybrids in WCA are likely to have at least 25-30% grain yield advantages over OPVs (similar to those reported in India), and hence a new initiative is underway to develop hybrids adapted to this region. The initial focus will be for more favorable areas with less risk of the need for re-sowing (after failure of seedling establishment) and where basal micro-dose applications of compost and/or phosphorus fertilizers are being adopted more widely.
Twenty-five OPVs, developed by ICRISAT in partnership with NARS from this region, have been released and adopted by farmers in nine countries in the WCA region. A total of 48 varieties were released in WCA, with some of these OPVs being released in more than one country. For example, the most popular varieties, SOSAT-C88 and GB 8735, have both been released in seven countries across this region, and ICMV-IS 89305 has been released in four countries. Limited seed production and distribution has been a major bottleneck and has slowed the spread of improved cultivars in the region.
Eastern and Southern Africa (ESA)
In Eastern and Southern Africa, pearl millet is cultivated on about 2 million ha. Twenty-eight OPVs developed by ICRISAT in partnership with NARS have been released in ten countries in the region. Of these, ICMV 88908, renamed as Okashana 1, has been released in more than one country. Okashana 1 and Okashana 2 have been adopted on a large scale, covering more than 50% of the total pearl millet area in Namibia prior to 2008. Similar to the situation in WCA, lack of seed production and distribution continues to be the major bottleneck in varietal spread and productivity increase in the ESA region also. For instance, during 1970-2006, there was only 15% productivity increase (from 800 kg/ha to 920 kg/ha) in the region.
A pearl millet mini-core collection of 238 accessions and representing diversity of the global collection has been developed and is available for crop improvement programs globally. Inbred panels derived from representative samples of the global collection are under development.