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Pennisetum americanum (L.) Leeke |
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Graminae P. glaucum (L.) R. Br.; P. typhoides (Burm.) Stapf and C.E. Hubb. Bulrush millet, pearl millet, dukn (the Sudan), bajra (India), babala (Natal). A robust and free-tillering annual growing to a height of 3 m. Stems 10-20 mm thick; above each node is a shallow groove containing an axillary bud. Nodes slightly swollen; they bear a ring of adventitious root primordia at the basal end. Leaves flat, dark green and up to 8 cm wide. The inflorescence forms a compact, cylindrical, terminal, spike-like panicle. There are 870-3 000 spikelets on a panicle. Seeds small, 3-4 mm, wedge-shaped of various colours according to variety. Originated in central tropical Africa, but cultivated since 1200 BC in India. Now widely distributed in the drier tropics. Summer. 800-1 800 m. It is grown in areas with an average annual rainfall of 125-900 mm, the lower rainfall areas using it as a grain crop where maize and sorghum fail. It is sown at low populations to allow each plant to find more soil moisture. Where dry matter for forage is the consideration, a minimum rainfall of 500 mm is required. Late rainfall is important for grain development in weeks 5-12. It is drought tolerant. Its roots may penetrate to 360 cm, although 80 percent of the root weight is in the top 10 cm. Bulrush millet grows on a wide range of soils, from sands in the Sudan to clays. It is tolerant of very acid soils. It grows best in a well-drained fertile soil. Practically nil.Land preparation for establishment For good crops it needs full seed-bed preparation as for cereals. In sandy soils in Africa, the ground is dug over with a hoe and weeded prior to planting. In peasant areas a few seeds are dropped in holes dug with a hoe, 45-90 cm apart according to rainfall, and covered. Mechanical drilling is common in developed countries. Sowing depth varies from 13-50 mm, the optimum being 35-40 mm. Early summer, at 6-10 kg/ha is usual when drilled in rows 35-70 cm apart. About 187 000.Seed treatment before planting Where needed, it can be dusted with a combined insecticide- fungicide. A one-hour soak in 1 percent 2-chloroethanol plus 0.5 percent sodium hypochlorite solution was found to be effective in increasing germination rates. Albert (1961) obtained effective control of the weedy Digitaria ciliaris (sanguinalis) and Amaranthus spp. by pre-emergence application of simazine at 1 kg, and atrazine and propazine at 1 and 2 kg/ha, without crop injury. 2,4-D at 0.5 kg/ha gave good weed control without crop injury if applied 21 days after sowing. Slow in the early stages of growth. It is good as temperature rises to 20-22°C.Vigour of growth and growth rhythm Norman (1962a) recognized three distinct development phases: an early tillering period, a period of rapid increase in dry weight and tiller height, and a period of head production. Full tiller production occurred in the fifth week with full light interception. Phillips and Norman (1967) recorded one of the highest growth rates recorded for any species when they measured the variety 'Ingrid Pearl', 14-16 weeks after sowing, as accumulating dry matter at the rate of 58 g/m2 per day. Flowering occurs about the thirteenth week. In the United States, three cuts of highly palatable green fodder are taken at six- to seven-week intervals. Late-maturing varieties are favoured for forage production. High regrowth yields after defoliation can best be obtained if the cutting height is above the apical meristem, and it is suggested that the crop be grazed rotationally when about 45 cm tall. Regrowth after later harvests declines rapidly (Begg, 1965). Pearl millet should be subject to relatively frequent but lenient defoliation to maintain quality. The crop should not be allowed to grow above 1 m high before grazing starts. Forage intake varied from a high of 3.1 kg DM/100 kg body weight on immature forage to a low of 1.4 kg on mature forage over a five-year period (Ferraris, 1973). Density of tiller regrowth after cutting was reduced from 54 percent when cut at 4 weeks to about 3 percent when cut at 14-16 weeks.Dry-matter and green-matter yields A yield of 21 735 kg DM/ha was recorded at Katherine, Northern Territory, Australia. In Alabama, United States, forage dry-matter yields varied from 6 000-10 500 kg/ha with 40 kg N/ha applied at sowing and again for each cut.In Queensland, Australia, Douglas (1974) recorded the following comparative dry-matter yields between Sudan grasses and pearl millet on a fertile, irrigated soil. Suitability for hay and silage Little hay has been made, and Norman and Stewart (1964) preferred a standing mature crop for dry-season grazing to conservation. However, the crop has been ensiled successfully in several countries (Ghana, Nigeria, the United States, Zimbabwe), and has proved the equal of maize silage when cut at eight to 12 weeks (full flowering). Chapman (1978), in Natal, found the best time to harvest was three weeks after flowering, when its dry-matter yield compared favourably with maize.Value as a standover or deferred feed Norman and Stewart (1964) found the crop excellent for dry-season grazing by beef cattle, and live-weight gains averaged 296 kg/ha over 16 weeks at Katherine, Northern Territory Australia, during a period when live weight on native pasture declined. Grazing lactating cows on millet has led to marked butterfat depression, and it has been suggested (Schneider et al., 1970) that high succinic and oxalic acids may be the cause. Under heavy nitrogen fertilization, high nitrate may be recorded. HCN contents are not sufficiently high to be hazardous to stock. Millet hybrids have been known to yield up to 6 t grain per hectare, but yields in the Northern Territory of Australia have been nearer 600 kg/ha.
Optimum temperature for growth Summer temperatures should be high. Maximum germination occurs at a day/night temperature of 20/25°C (R.M. Hughes, 1979).Minimum temperature for growth 7.0°C + 6.3. Low temperatures retard germination and at 10°C, photosynthesis is negligible (Russell & Webb, 1976). Temperatures near 0°C are lethal. 14-32°N and S (Russell & Webb, 1976).y Most crops of pearl millet are sown in rows and cultivated between the rows. Where fodder crops are grown at high densities the crop canopy suppresses weed growth.Maximum germination and quality required for sale 70 percent germinable seed, 97.3 percent purity (Queensland). In Africa one of the worst pests is the root parasite, Striga hermonthica, and less commonly S. Iutea. The red-billed weaver bird, locusts and Quelea quelea aethiopica take heavy toll. Heliothis armigera attacks seed-heads, and the stem borer, Coniesta ignefusalis, is also damaging. Ferraris (1973) gives a full list of pests. Young pearl millet is very palatable. Both day-neutral and short-day varieties exist. Burton and Powell (1968) suggested that short-day, photoperiod-sensitive, late-maturing millets should be superior to the other lines since they are leafier and have a better seasonal distribution of forage production. Grain production would best be improved by the use of photoperiod-insensitive types which mature early. The crop would thus escape drought and could be planted several times a year if conditions were favourable.Chemical analysis and digestibility The crude protein content depends on the age of the crop, young growth giving the highest proportion. Dry- matter digestibility ranges from 75.3 percent in young pearl millet leaves to 61.4 percent in old leaves. The lowest digestibility figure was 55 percent in mature, previously-grazed stands which were making slow recovery (see also Digitaria ciliaris). Cultivation. It does not tolerate flooding, especially during the summer. Bulrush millet is seldom manured by villagers in Africa; in India, farmyard manure may be used, and African nomads plant it on village cattle camps when the herds go on trek. The most common fertilizer element in use under cultivation is nitrogen at 60-100 kg N/ha, balanced with about half this level of P2O5, and potassium as needed. For use as fodder higher nitrogen dressings may be used. Bulrush millet has an outstanding ability to recover deep accumulations of nitrate nitrogen from soils. In the United States, fodder dry matter responds to fertilizer nitrogen up to 400 kg/ha.Compatibility with other grasses and legumes It is usually grown as a pure stand. In India it has been grown with Cajanus cajan, the mixture providing a useful cover to reduce soil erosion. 2n=14; the haploid chromosome number in pollen mother cells is thus 7. Burton and Powell (1968) consider millet to be an excellent plant for genetic and cytogenetic research, as the small number of large chromosomes and the clear meiotic stages allow detailed study. Interspecific hybridization of P. americanum has usually only been successful with P. purpureum. Bana grass is one such cross and is widely used in south-east Queensland as a wind- break on vegetable farms; it also provides useful fodder. A millet-breeding unit is centred on the EAAFRO, Serere Research Station in Uganda and at Coastal Plains Research Station, Tifton, Georgia, United States.Seed production and harvesting Seeds are ready to harvest three to four weeks after anthesis. They vary from 3 to 10 mg in weight. Uneven ripening of tillers necessitates multiple harvests where manual methods are used. The seed can be harvested directly by combines, but for tall varieties a roller attached in front of the comb will make the harvesting height easier to handle. Pearl millet is an important grain crop in Africa where the rainfall is not secure enough for sorghum or maize. In the United States and Australia it is a useful, non-toxic forage to replace forage sorghum. The stalks are used in the dry tropics for home building. In southern Africa, pearl millet yielded an average of 25.2 tonnes of green matter (Haylett, 1961). Clark, Hemken and Vandersall (1965) found pearl millet equivalent to Sudan grass and a sorghum x Sudan grass hybrid for dry- matter yield, carrying capacity and milk yield for lactating cows. Carrying capacity varied from 4.7 to 6.7 cows per hectare per day with millet over a three-year period, and adjusted milk production averaged 19.8 kg per day. Body weight losses were least with millet. The grazing season averaged 121 days. At Katherine, in the Northern Territory, Australia, wet season grazing by beef cattle at a stocking rate of 2.5 beasts per hectare produced a live-weight gain of 102 kg per head in 20-24 weeks, an increase of 51 kg per head over native pasture (Norman, 1963b). Cattle grazing standing millet in the dry season made an average live-weight gain of 269 kg/ha over 16 weeks, during a period when animals grazing natural pasture lost weight (Norman & Stewart, 1964). Between January and March in the Macquarie Valley, New South Wales, irrigated cv. MX 001 yielded 18 950 kg DM/ha and 274 kg/ha of live-weight gain, 0.95 kg per day on a per caput basis (Upton, 1978). At Katherine, Northern Territory, Norman and Phillips (1968) conducted 18 grazing trials (from 1960 to 1967) with pearl millet. Burton & Powell, 1968; Ferraris, 1973; Muldoon & Pearson, 1979; Vicente-Chandler, Silva & Figarella, 1959. Several reports state that the seed of pearl millet exhibits post harvest dormancy of several weeks. In pure stands (for seed production) it affords little soil protection, but in dense stands (for forage production) or in conjunction with a legume, for example Cajanus cajan in India, it is useful. It is tolerant of salinity and was used for reclamation of salt lands in Sind because of its ability to take up salts (Tamhane & Mulwani, 1937; Ravikovitch & Porath, 1967). Soil salt concentrations of 1 400 to 2 600 ppm produced only slight tip burn (Smith & Clark, 1968).#S
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