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Andrews, D.J., J.F. Rajewski, and K.A. Kumar. 1993. Pearl millet: New feed grain crop. p. 198-208. In: J. Janick and J.E. Simon (eds.), New crops. Wiley, New York.

Pearl Millet: New Feed Grain Crop*

David J. Andrews, John F. Rajewski, and K. Anand Kumar


  1. CLASSIFICATION AND DOMESTICATION
  2. BIOLOGY AND ADAPTATION
  3. BREEDING
    1. Yield Potential
    2. Breeding in the USA
  4. GRAIN QUALITY AND FEED VALUE
  5. CULTIVATION
  6. CONCLUSION
  7. REFERENCES
  8. Table 1
  9. Table 2
  10. Table 3
  11. Table 4
  12. Table 5
  13. Fig. 1

Pearl millet, [Pennisetum glaucum (L.) R. Br.] also known as bulrush or cattail millet, is the most important of a number of unrelated millet species grown for food worldwide on a total of 40 million ha (FAO 1986). Though figures are not available for separate species in all countries, pearl millet is grown on about 26 million ha in the warm tropics divided equally between Africa, particularly in the West African Sahel region, and the Indian subcontinent. In these areas, pearl millet is grown almost exclusively as human food, and indeed is the staple cereal of 90 million people who live in agroclimatic zones where there are severe stress limitations to crop production due mainly to heat, low and erratic rainfall, and soil type. Since fertilizers are not used and cultivation is by hand or animals, actual grain yields are low in these regions (~500 to 600 kg/ha), yet they are higher and more reliably obtained than from other possible tropical dryland cereal crops such as sorghum or maize. Grain is always the principal object of cultivation, but the stover is secondarily important as animal fodder, and stems can be used as fuel, fencing, and roofing.

CLASSIFICATION AND DOMESTICATION

Pearl millet is a cereal belonging to the genus Pennisetum which contains about 140 grassy tropical species. Previous names have been P. typhoides (Burm) Stapf. & Hubb., P. typhoideum (L.) Rich., and P. americanum (L.) Leeke, possibly because Clusius, in 1601, thought the type specimen he obtained from southern Spain had come from the Americas.

It is generally agreed that pearl millet was domesticated in Africa, probably on the southern edge of the Sahara, west of the Nile, some 3,000 to 5,000 years ago and subsequently spread to southern Asia (Harlan 1975; Brunken et al. 1977). The gene flow from probable progenitor wild species [spp. monodii (syn. P. violaceum Maire)] still occurs in West Africa, where weedy segregates (spp. stenostachyum Klotzsch) are common in cultivated varieties. The frequency of occurrence of these segregates declines through eastern to southern Africa, and they are absent in Asia.

BIOLOGY AND ADAPTATION

Pearl millet is a highly tillering, cross-pollinating diploid tropical C4 cereal with grain on the surface of erect candle shaped terminal spikes. Grain size varies from 0.5 to over 2.0 g/100, and, depending on head size, grain number per head ranges from 500 to 3,000. Pearl millet tillers freely, compensating well for stand irregularities, and produces 2 or 3 times more heads per plant than sorghum at similar plant populations.

Three germplasm pools are recognized in respect of cultivated pearl millet (Harlan and de Wet 1971). The primary pool contains all cultivated, weedy, and wild diploid (2n = 14) pearl millets which are freely cross-fertile. The secondary pool is solely P. purpureum (Shum.) (2n = 28), elephant or Napier grass, a vigorous perennial species also from Africa. The cross between pearl millet and elephant grass is easily made (but is sterile unless the chromosome number is artificially doubled) and is widely used as a forage propagated by cuttings. Hanna (1990, 1991b) has demonstrated that part of the purpureum genome can be usefully transferred to pearl millet. The tertiary pool contains numerous more distantly related Pennisetum species of various ploidy levels which do not naturally interbreed with the primary pool, but can potentially be accessed through various wide crosses (Dujardin and Hanna 1989, 1990).

The cultivated gene pool in pearl millet contains a truly enormous range of genetic variability with no incompatibility and few linkage problems. Many important physiological and morphological traits essential for breeding a crop suitable for combine harvesting are readily available. These are reduced plant height and early maturity--independent of photoperiodic control, synchrony of tiller flowering, angle of tillering, stem and peduncle thickness, peduncle length, grain color (white or cream simply dominant over gray), and mesocotyl length. Ample variation exists for head size (length ' diameter) and grain number and size though, as expected, correlations between yield components are large and negative.

In areas where frost-kill can occur before harvest, standability is crucial. Both peduncle and stem lodging resistance are evident in inbred stocks, but most material is susceptible and this is one trait which will require much breeding attention. Differences in tolerance to some herbicides (propachlor and atrazine) have been noted and incorporated in selection and breeding strategies.

BREEDING

The floral morphology, breeding behavior and the structure of grain yield in pearl millet make it one of the most flexible and responsive crop species to breed. It appears possible to access genetic variability both from the secondary and tertiary germplasm pools (Hanna 1990; Dujardin and Hanna 1989, 1990). Pearl millet has relatively few large chromosomes and RFLP and RAPD techniques can be used (R.L. Smith pers. commun.).

Pearl millet is a naturally cross-pollinating species, which is achieved through protogyny, since all the sessile flowers on each head are perfect (i.e. both male and female fertile). On any one head, all flowers first exert stigmas over a 1 to 3 day period progressing from the mid-top to the bottom of the head. Anthesis occurs one to as many as 4 days later, in the same sequence from the same flowers, and sometimes, later from the pedicellate flowers. Thus, there is a period for each head, when flowers can only be fertilized by external pollen which is freely wind-born. Stigmas wither about 8 h after pollination. Self-pollination can occur when stigma emergence on later flowering tillers overlaps with the anthesis of earlier heads on the same plant. In random-mating situations (as in landrace cultivar populations or breeder created populations--synthetics or composites), the amount of self-pollination (considerations of common parentage and effective population size apart) is influenced by the degree of tillering, relative size and flowering relationships of tillers, and whether all or only primary tillers are harvested. As a generality, about 20% selfing is normal (Burton 1974; Chirwa 1991).

Selfed seed in pearl millet can be produced simply by placing a bag over a head prior to stigma emergence. If the stigmas are not short lived, 100% selfed seed set will then occur. Similarly, 100% hybrid seed can be made by pollinating a previously bagged head once at full protogyny prior to anther emergence. The breeding opportunities in pearl millet can be illustrated by the following: each of 3 heads on one plant in a population (tillering can be promoted by planting at reduced density) can be used for different objectives--one can be selfed, one crossed (full-sib, testcross, topcross) and one left to random-mate. Seed from each head will be sufficient to plant 20 plots each of 7.5 m2.

At least four cytoplasmic-genic systems causing male sterility (CMS) are available in pearl millet (Kumar and Andrews 1984; Hanna 1989). The first and currently most widely used source (now termed A1) was discovered by Burton (1958) in Tifton, Georgia, and released as Tift 23A in 1965 (Burton 1965). All forage hybrids in the United States are made with this CMS system. Its most extensive use, however, has been in grain hybrids in India, where an average of over 2 million ha have been grown annually over the last 23 years.

New lines in which male sterility is stable in all environments are difficult to breed in the A1 system and have never been obtained with A2 and A3. The Am source (Hanna 1989) using monodii cytoplasm is more stable and appears easier to breed, but restorers are scarce and hybrids have not been widely tested. An additional source of CMS has been reported by Marchais and Pernes (1985) but its relationship with others has not been established.

Pearl millet resembles maize in many respects in regard to gene action in performance traits. In general, additive effects are larger than non-additive effects, which can however be significant. Inbreeding depression is large--some 30% from one generation of selfing in populations (Khadr and El-Rouby 1978; Rai et al. 1984); however, vigorous inbred lines yielding 60 to 70% of open-pollinated cultivars of comparable maturity can be selected. As a generality, good hybrids will yield 20 to 30% more than the best open-pollinated cultivars of comparable maturity (Table 1) (Andrews and Rajewski 1990, 1991; Dave 1986).

With the correct selection of parent lines in regard to phenotype and relative maturity, hybrids can also be made in pearl millet by utilizing the natural period of protogyny. This method allows quicker hybrid development, greatly increases the range of possible parent combinations, and avoids diseases which are associated, particularly in Africa, with the use of CMS seed parents. These pro-hybrids, as they are termed, appear to have the most utility for developing countries where existing or reselected leading open-pollinated cultivars could be directly used as male parents for topcross hybrids.

Heterotic effects in pearl millet are large and most completely expressed in single crosses, though yields from topcross hybrids are similar in all but the highest yielding situations. Topcross hybrids have several advantages including stability and durability of performance and ease of production (Andrews 1986).

Yield Potential

Landrace open-pollinated cultivars of pearl millet exhibit high levels of vegetative vigor and a very high biomass production. These are necessary adaptive features for the crop to survive stressful low fertility conditions, pests, diseases, weed competition, yet take advantage of brief periods favorable for growth and still yield consistently. As a result, the harvest index of these traditional cultivars which are tall, is only 15 to 20%. A crop of a local variety of pearl millet, cv. ex Bornu, grown under high fertility conditions without irrigation, in northern Nigeria produced 22 t/ha of above ground dry matter 90 days after sowing, but only 3.2 tons of this (14.5%) was grain (Kassam and Kowal 1975). In contrast, grain yields on a field basis of over 5 t/ha were produced by semi-dwarf hybrids maturing in 85 days in India (Rachie and Majmudar 1980) where experimental yields of up to 8 t/ha have been reported (Burton et al. 1972). The harvest index in these genotypes has been improved to over 40%. The Indian hybrids, however, though their yield potential is high, do not possess the persistent stem strength needed for mechanical harvesting and are still partly photosensitive and thus mature too late when planted more than about 30deg. latitude from the equator. New phenotypes are required for Midwestern United States which should be non-photoperiod sensitive, early to very early, with sufficient stalk and peduncle strength, and an upright tiller habit to give effective lodging resistance following frost. There have been relatively few notable breeding achievements in the improvement of grain production in pearl millet. The first was the breeding of high yielding early maturing semi-dwarf hybrids in India in the 1960s, mentioned above, which was made possible by the crucial discovery of cytoplasmic male sterility and its incorporation of it into a semi-dwarf line of high combining ability (Burton 1965). The second was that when successive early hybrids broke down to the downy mildew disease [Sclerospora graminicola (Sacc.) Schroet] in India, open-pollinated cultivars were then bred in the late 1970s that combined durable disease resistance with yield levels nearly equivalent to the hybrids (Andrews et al. 1985). Currently, these high yielding cultivars occupy about the same area in India as newer hybrids, now with better disease resistance (ICRISAT 1990). The third achievement, which was slow to develop and has had less impact due to limited seed multiplication and extension efforts, was the generation in the early 1970s of widely adapted varieties from Serere, Uganda, with Iniati/Koupela parentage. These proved superior in tests and have been released in countries from Sudan to Botswana.

Breeding in the USA

The foundation for breeding pearl millet grain hybrids in both India and more recently in the United States traces directly back to the pioneering research done by Glenn Burton in the forage crops program at Tifton, Georgia, which commenced in 1936. Besides CMS, dwarf stocks with early maturity and other valuable information about pearl millet breeding and genetics have been produced from Tifton. The development of forage cultivars in the United States in the past 50 years, mostly due to research at Tifton, has progressed from open-pollinated cultivars, through synthetic cultivars, poly-cross F1s to single-cross hybrids. Advances have been made in both biomass productivity and digestibility, the latter largely through the use of dwarfing genes to increase leaf/stem ratio. Tolerance to nematodes and diseases have been incorporated (see review by Andrews and Kumar 1992).

Why breeding grain hybrids in pearl millet did not immediately commence in the United States in the 1960s to parallel hybrid development in grain sorghum is not clear. Contributing factors may have been that grain production in sorghum was already established using dwarf and semi-dwarf inbred varieties that mostly had sufficient stalk strength to be combine harvested; and there was a relatively much larger germplasm base of adapted sorghum stocks from which to breed whereas the initial stocks from the Tifton program were phenotypes primarily intended for use in forage production. Also in the 1950s and 1960s, the relative nutritional advantage of pearl millet grain compared to sorghum was not widely appreciated.

In 1969, Kansas State University began a grain breeding program in pearl millet at Manhattan, Kansas, which grew partly out of the USDA/OAU joint Cereals Research Project 26 in Africa, which supported genetic research in pearl millet at Serere, Uganda. The millet breeding program at the Fort Hays Experiment Station started in 1971. Early sources of germplasm for the Hays program came from both East and West Africa; India; Tifton, Georgia; and the USDA Plant Introduction Station pearl millet germplasm collection, Experiment, Georgia. While the Tift A1 cytoplasm has been the basis for the development of seed parents at Kansas State University, another accession (PI 185642) from the Ghana/Togo landrace called Iniati/Koupela, has been a parent of fundamental importance in transmitting the character associations of large (12 to 16 g/1000), round, slate-gray or yellow grain, relatively large head width/length ratio, good combining ability, and earliness uninfluenced by photoperiod response. Dwarf derivatives of another Togo type cultivar (Serere 3A) have contributed early maturity, large seed size, and high grain yield potential to numerous imported accessions, inbred lines, and populations used as sources of pollen parents of experimental hybrids. The breeding value of the Iniati/Koupela germplasm was independently recognized in breeding programs in India, East and now West and Southern Africa. Seed parents from Hays lines have been released via ICRISAT in India, and are used extensively in hybrid production in northwest Indian states.

Work at Hays, Kansas, now supported by INTSORMIL, is focused on improving stand establishment, fertility restoration, and lodging resistance--characteristics necessary for mechanized production of hybrid millet. Large seed size and ability to emerge from deep (7.5 to 10 cm) field plantings have been selected at Hays to overcome establishment difficulties (Stegmeier 1990). These materials emerge from normal planting depths up to one day earlier than unselected lines, which is advantageous when weather conditions cause either crusting or rapid drying of seedbeds.

Fertility restoration of the A1 cytoplasm has been difficult to stabilize within the variable environment of the central Great Plains, but inbred lines have been identified that have consistently produced fertile hybrids in 20 or more tests during the past five years.

Severe stalk lodging and breaking of stem internodes occurs within all germplasm sources, lines, and hybrids selected for improved grain yield. Two sources of improved stalk quality have been found that reduce the incidence of lodging and are being incorporated into elite inbred lines.

Grain yield levels of up to 5.3 t/ha have been recorded (Christensen et al. 1984). Grain yield comparisons of sorghum and pearl millet hybrids of similar maturities (W.D. Stegmeier unpubl. data) indicate millet yields are to 60 to 90% as large as sorghum when grown on silty clay loam soils, 85 to 100% on silt loams, and will often exceed the yield of sorghum on sandy soils. On sandy soils in southcentral Kansas, Stegmeier (1990) reported pearl millet hybrids producing up to 76% more grain than the commercial sorghum hybrid check yield of 2.4 t/ha.

Research on grain production started as an adjunct to the on-going pearl millet forage breeding and wide crossing program at Tifton, Georgia, in the early 1980s. Dominant resistance to pearl millet rust (Puccinia substriata Ell. & Barth. var. indica Ramachar & Cumm) and blast (Piricularia setariae Nisikado) has been incorporated into A1 seed parents (Hanna 1991a), while pollen parents have been obtained from crossing the doubled (6x) pearl millet x elephant grass cross back to pearl millet (Hanna 1991b). A hybrid (Tift 90DAE x 8677), with these parents has been released under an exclusive license and is being grown on a pilot scale of a few hundred hectares in 1991 on the sandy soils of Georgia and South Carolina.

The breeding program for grain pearl millet commenced at the University of Nebraska-Lincoln and High Plains Agricultural Station at Sidney in 1984 with the support of INTSORMIL. Germplasm introduced earlier had been random-mated into a population early enough to mature in western Nebraska. Breeding material was extensively introduced from India and Africa. Both population and pedigree breeding are being used to produce adapted inbreds for use as hybrid parents, in synthetics, and to make new populations. New seed parents have been produced in A1 cytoplasm with improved seed set and lodging resistance. Seed and pollen parents are also being produced with the Am (monodii) cytoplasm.

The possibility of producing hybrids by using the species natural protogyny, which would increase potential hybrid combinations and greatly reduce hybrid development time, is currently being investigated (Andrews 1990). Tests with mechanical mixtures of "seed parent" lines and pro-hybrid seed have been conducted to estimate the effect on hybrid performance of any self-pollination that might occur in the pro-hybrid seed parent during hybrid seed production. Provided the hybrid has a dominant phenotype, no significant loss in hybrid yields was found in three different hybrids when 20% inbred seed of the female parent was added (Andrews 1990). Actual losses were from 4 to 6% (for detailed results see Andrews et al. 1993 in this vol.). Much less than 20% selfing would be expected in a well managed seed plot. Protogynous hybrids, therefore, seem feasible to produce and may be particularly useful in African situations.

Pearl millet regional grain yield trials testing initial experimental hybrids and other entries from ARS/USDA, Tifton, Georgia; Kansas State University, Hays; and University of Nebraska, Lincoln; have been grown cooperatively at 5 locations in the United States since 1988 (Fig. 1). The 1990 results shown in Table 1 are typical. Across locations the best pearl millet hybrids averaged 85% of the grain yield of the sorghum hybrid checks. Only where the season was short as in North Dakota, and in double cropping after wheat in Indiana (sorghum failed to mature) did millet yields exceed sorghum. Considerations of maturity, height, lodging, leaf disease occurrence, and relative genotype yields suggest that there are at least two contrasting adaptation areas within the region in which the tests have been conducted. These are the Midwest High Plains and the Southeast. Cultivars from the Southeast are too late maturing in the Midwest (will mature in Kansas but require more moisture), tend to be tall, and have little resistance to lodging following frost. Conversely, Midwest cultivars are too early in the South, and have little resistance to leaf diseases.

GRAIN QUALITY AND FEED VALUE

Results from feed experiments involving pearl millet with maize or sorghum from literature reviewed by Hoseney et al. (1987), Rooney and McDonough (1987), Serna-Saldivar et al. (1990), Sullivan et al. (1990), and Bramel-Cox et al. (1992) indicate that pearl millet is at least equivalent to maize and generally superior to sorghum in protein content and quality, protein efficiency ratio (PER) values, and metabolizable energy (MEn) levels. Pearl millet does not contain any condensed polyphenols such as the tannins in sorghum that can interfere with or slow down digestibility.

Recent chick feeding experiments, Sullivan et al. (1990) (Table 2) and Hancock et al. (1990) (Table 3) show that weight gains and feed/gain ratios obtained in pearl millet based diets are equal to that of maize and some sorghums. Smith et al. (1989) similarly report that pearl millet can replace maize in chick diets without affecting weight gain or feed efficiency. Both the gross energy and MEn values of pearl millet tend to be higher then those of maize and many have been previously underestimated by 20% (Fancher et al. 1987). Tribble et al. (1986) reported that they were also able to substitute pearl millet for sorghum in sorghum based diets for growing pigs without affecting performance. Calder (1955, 1961) had previously concluded that pearl millet was suitable for pig feeding.

Studies on the comparative value of pearl millet with sorghum or corn for cattle are few. When millet and sorghum grain were compared in high-silage growing rations for steers adjusted to equal protein intake, the results suggested millet protein had a high biological value as the addition of Rumensin to the rations gave millet grain a 10% advantage over sorghum grain (Brethour 1982) (Table 4). With finishing steers, Brethour and Stegmeier (1984) comparing rations where 25% of the sorghum component was replaced with pearl millet, reported that average daily gains were 1.40 and 1.20 kg, and feed/gain ratios were 7.53 and 8.03, respectively, for millet based versus sorghum based diets. Estimated net energy value of pearl millet was 4% higher than for sorghum. In both experiments, the amounts of soybean meal and/or urea needed for iso-N rations were less when pearl millet was used.

In a metabolism trial with steers, Hill and Hanna (1990) compared a diet with 79% pearl millet (PM) to diets of 76% sorghum + 2.8% soybean meal (GS) with a control (C) of 73% maize + 6% soybean meal. Ether extract and crude protein digestibilities were higher for C and PM than GS while retained N was similar for all. In an accompanying growth trial with yearling heifers, diet C gave a higher daily gain than PM, but feed:gain ratios were similar for all diets (8.5, 9.1, and 8.2 kg feed/kg gain-1, respectively, for PM, GS, and C).

In general, feeding test results support data from biochemical analyses which indicate that pearl millet is similar to maize and superior to sorghum as a feed grain. A number of factors are thought to be responsible. Pearl millet grain generally has a higher crude protein level by 1 to 2 percentage points relative to sorghum grown with similar cultural practices. Pearl millet is still deficient in essential amino acids, but averages 35% more lysine than sorghum (Rooney and McDonough 1987). Pearl millet grain has 5 to 6% oil and a lower proportion of the less digestible cross-linked prolamins (Jambunathan and Subramanian 1988). These differences can be partly attributed to the different structure of the kernel. The proportion of germ in pearl millet grain (17%) is about double that of sorghum, while the endosperm accounts for 75% as against 82% in sorghum (Table 5). Amounts of bran are similar.

Major recessive genes that strongly influence grain protein lysine levels, as discovered in sorghum and maize, have not been found in pearl millet, despite an extensive survey of the world collection. However, selection for grain protein level in pearl millet has resulted in inbreds where crude protein levels (and consequently higher levels of lysine per sample) are 4 to 6 percentage points higher than normal, without affecting endosperm development (Singh et al. 1987). Hybrids made between these high protein inbreds and normal parents gave normal yield levels but with some elevation in grain protein, indicating partial dominance for the expression of grain protein content (ICRISAT 1984). It would appear possible to breed for moderately higher protein grain content levels (and higher lysine/sample) in pearl millet without the use of a high lysine gene that adversely affects endosperm development.

CULTIVATION

Cultivating, harvesting, and handling a pearl millet crop for grain with existing equipment and in ways similar to current farming practices, will be important for its successful adoption. Hybrid plant types are being bred with this in mind. Existing hybrids can be grown as a row crop like grain sorghum with some adjustments. Pearl millet establishes best when sown slightly shallower than sorghum in well prepared warmer seed beds on well-drained soils. It tolerates many of the post-emergence broad-leaf herbicides (bentazon, bromoxynil, and 2,4-D), but so far among the pre-emergence herbicides that control grassy weeds, only half rate atrazine is tolerated. (Selection is underway for propachlor resistance--see below). Plant densities should be similar or slightly higher (100,000 to 175,000 plants/ha) than for sorghum. The grain is tougher and more dense than sorghum and can be easily combined when well dry using higher cylinder speeds, more air and adjusting the screens for the smaller seed size. The point at which pearl millet is dry enough for harvesting can be easily judged in the field. When the crop is ripe and dry, grains will pop out cleanly when the head is pinched. The grain flows easily and trucks and grain bins do need to be completely grain-tight.

More agronomic research is needed now that new hybrids are available, particularly on seedling establishment and control of grassy weeds. Preliminary observations at UN-L indicate that the choice of hybrid phenotype (medium maturity, 120 to 130 cm height, elongated, and closed canopy), planting date (delay sufficient to allow germination and removal of some grass seed), and row spacing (mechanical cultivation of wide rows vs non-cultivated narrow rows) are important in reducing competition effects of foxtail and fall panicum grasses. Pearl millet seed protectants and safeners are not available for use with the amide family of herbicides (metolachlor and alachlor). We have made good progress at the University of Nebraska, Lincoln on selecting for propachlor tolerance and the tolerance is not limited to one source of germplasm. Selection for large seed size and long mesocotyl at Kansas State University, Hays has identified genotypes with better seedling establishment and early growth which thus can be planted a little deeper into assured moisture.

Apart from the rust and leaf blast in the South, no major diseases have so far been identified on pearl millet in the Midwest. Bacterial leaf spotting caused by (Psuedomonas syringae pv. syringae van Hall) (Odrody and Vidaver 1980) has occasionally occurred in July in pearl millet forage crops, but subsides later in the season. Increased stalk lodging can occur in high nitrogen soils (>112 kg N/ha) with some hybrids. As with sorghum, some peduncle attack of the European corn borer [Ostrinia nubilalis (Hübner)] can occur and cinch bugs [Blissus leucopterus leucopterus (Say)] can spread to pearl millet from adjacent wheat to increase head and stalk lodging or kill plants during the growing season. Pearl millet has two distinct advantages over sorghum or proso--its seed will not over-winter in moist soil, and there are no wild relatives in the United States to which it will naturally outcross, so it would not become a weed in subsequent crops.

CONCLUSION

Pearl millet is a widely grown Old World tropical food cereal well adapted to the hot drought prone areas of Africa and the Indian subcontinent where about 26 million ha (about 7 times the United States grain sorghum area) is grown. A very wide range of genetic variability is available in the primary germplasm pool for improvement of this species where genetic manipulation is facilitated by its tillering protogynous habit and high seed number per head. Sustained advances have been made in the United States since the 1940s on breeding pearl millet forage cultivars. The resulting genetic information and the discovery of CMS has been vital for breeding for grain yield.

Following the demonstration of the yield potential of early maturing hybrids in India, breeding commenced in the early 1970s on grain pearl millet in the United States at Kansas State University, Hays and was joined in the 1980s by USDA/ARS Tifton and the University of Nebraska-Lincoln and Sidney. Fully dwarf experimental hybrids which can be grown like sorghum have been produced and tested regionally since 1988, giving yields averaging 2.3 to 3.8 t/ha. Highest yields on a field basis (5.3 t/ha) were recorded in Kansas. Two adaptation zones, the Southeast and Midwest High Plains are evident from these tests.

Feeding tests on cattle, swine, and particularly chickens have shown pearl millet is at least equivalent to maize and often superior to sorghum in feed rations, generally because of high energy and grain protein levels.

Initial breeding efforts and utilization tests have given encouraging results. Further cultivar improvements can be expected. Opportunities for production will be dependent on a number of factors including marketing possibilities, which may first be by specific contracts. Clearly, more agronomic research is needed on determining optimum cultivation practices, but pearl millet crops can presently be grown well with existing row crop equipment and practices. Potential production areas are those where pearl millet will have a relative advantage over other summer cereals, such as in the Southeast coastal sands, in the drier or short-season parts of the Midwest High Plains, and possibly in double-cropping after wheat in the central Midwest.

REFERENCES


*Joint contribution of the Department of Agronomy, University of Nebraska, research in part supported by USAID S&T Grant No. DAN-1254-00-0021-00 to INTSORMIL, and International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).
Table 1. Mean grain yields in 1990 pearl millet regional grain yield trial.
Mean grain yield (kg/ha)
Georgia Indiana Kansas Nebraska North Dakota
Entry Tifton Lafayette Hays Mead Sidney Carrington
MLS variety 2640 2990 2340 3120 3540 3090
68A x MLSz 2300 3790 3120 4130 4440 3670
EDS variety 2600 3120 2190 2360 3320 2580
68A x EDSz 2980 3780 3070 3610 4360 3670
90PV0046 x 0049y 2640 3060 1920 2670 3190 1510
90PV0003 x 0005y 4790 2570 2460 4010 3480 790
90PV0016 x 0017y 3690 2980 2320 2900 2560 2730
90PV0016 x 0015y 3220 3330 2840 4050 3770 2190
H23DA1E x 77x 2950 1930 1260 3720 2510 810
RR23DAE x 77x 4950 2320 1180 4020 2590 1380
1163 x 86-7907x 2670 3960 3130 3330 3670 3810
2068 x 87-8025x 4610 2930 1990 3830 3030 2220
DK 39 sorghumx 5650 --- 4860 6090 4170 1210
F 2233 sorghumx 5840 --- 3660 5660 5220 2720
Mean 3680 3060 2590 3820 3560 2310
CV 24 20 13 14 13 28
LSD 0.05 1509 1064 551 934 787 1088
zcms topcross
ypro-hybrid single cross
xcms single cross
Table 2. Performance of broiler chicks fed pearl millet, maize, high (HT) and low (LT) tannin sorghum based dietsz.
Grainy Added fat (%)xWeight gain (g) d 1 to 42Gain:feed d 1 to 42
Pearl millet 9.0/9.8 1466aw 0.472a
Maize 4.0/3.8 1372ab 0.469a
Sorghum, HT 9.6/9.8 1384ab 0.426b
Sorghum, LT 5.7/6.0 1329b 0.448ab
zSullivan et al. (1990).
yDiets were isocaloric and iso-N; five replications of 60 birds/treatment.
xFat levels in the starter/grower diets.
wMean separation by Duncan's Multiple Range Test, 5% level.
Table 3. Nutrient content of pearl millet, sorghum, and maize and growth performance of broiler chicksz.
Crop Crude protein
(%)
Lysine
(%)y
MEn
(kcal/kg)y
Gain
d 7 to 21 (g)
Gain/feed
Pearl millet 10.3 0.35 3459 475 0.656
Sorghum 11.0 0.27 3397 467 0.638
Maize 10.1 0.30 3288 479 0.654
zAdapted from Hancock et al. (1990).
yCorrected to 90% dry matter.
Table 4. Rolled pearl millet compared to rolled sorghum in high silage steer growing rationsz.
Avg daily ration (kg)
Ration Sorghum
silage
Rolled
sorghum
Rolled pearl
millet
Soybean
meal
Premix Air dry
total
Avg. daily
gain (kg)
Kg feed/
45.4 kg gain
Control
Pearl millet 18.0 --- 2.1 0.26 0.14 8.6 1.08 359
Sorghum 18.9 1.8 --- 0.56 0.14 8.8 1.11 368
Rumensiny
Pearl millet 17.5 --- 2.1 0.26 0.18 8.4 1.18 337
Sorghum 17.8 1.8 --- 0.56 0.18 8.5 1.07 364
zAdapted from Brethour (1982).
yNo endorsement is intended, nor is any criticism implied of any similar product not mentioned.
Table 5. Percent anatomical grain composition and protein content of pearl millet and sorghum grain fractions.
Pearl milletz Sorghumy
Grain fraction % of grain Protein % of grain Protein
Endosperm 75 10.9 82.3 12.3
Germ 17 24.5 9.8 18.9
Bran 8 17.1 7.9 6.7
Whole grain 100 13.3 100 12.3
zAbdelrahman and Hoseney (1984).
yHubbard et al. (1950).

Fig. 1. Dwarf pearl millet grain hybrid (protogyny type), 1990 Pearl Millet Regional test, Hays, Kansas (2-row plots).


Last update September 10, 1997 aw