West Africa is a center of origin and diversity of pearl millet [Pennisetum glaucum (L.) R. Br.], but this diversity is neither well-understood nor fully accessible to and exploited by NARS breeders and farmers. The objective of the present study was to multiply and initially characterize 281 pearl millet accessions from all over West and Central Africa, with the final aim of promoting a more systematic and targeted exploitation of genetic diversity in adapted germplasm in West African pearl millet improvement programs

Boubacar, A

Boureima, S S

Haussmann, B I G

Vigouroux, Y

ICRISAT Open Access Repository

110 ISMN 47, 2006Multiplication and Preliminary Characterization of West and CentralAfrican Pearl Millet LandracesBIG Haussmann1*, A Boubacar2, SS Boureima2 and Y Vigouroux3[1. International Crops Research Insitute for the Semi-Arid Tropics (ICRISAT), BP 12404, Niamey, Niger; 2. UniversitéAbdou Moumouni, BP 10662, Niamey, Niger; 3. Institut de la Recherche pour le Développement (IRD), BP 11416, Niamey, Niger]*Corresponding author: b.ig.haussmann@cgiar.orgIntroductionWest Africa is a center of origin and diversity of pearlmillet [Pennisetum glaucum (L.) R. Br.], but this diversityis neither well-understood nor fully accessible to andexploited by NARS breeders and farmers. The objectiveof the present study was to multiply and initially characterize281 pearl millet accessions from all over West and CentralAfrica, with the final aim of promoting a more systematicand targeted exploitation of genetic diversity in adaptedgermplasm in West African pearl millet improvementprograms.Materials and MethodsThe 281 pearl millet accessions originated from ninecountries of West and Central Africa: Benin (22 accessions),Burkina Faso (42), Cameroon (10), Central African Republic(9), Guinea (10), Mali (80), Mauritania (8), Niger (70)and Senegal (30). The accessions had been assembledduring joint collections by the Institut de la Recherchepour le Développement [IRD; formerly called the Officedes Recherches Scientifiques et Techniques d’Outre-Mer(ORSTOM)] and ICRISAT in 1976 and 2003, and wereobtained from IRD-Montpellier and IRD-Niamey. Geo-graphically, these accessions cover longitudes from8°44′E to 17°28′W and latitudes from 6°49′N to 20°26′N.Since the primary objective was to multiply eachaccession to an adequate effective population size, theaccessions were grown in nonreplicated plots of 3–10rows (depending on seed availability) in the rainy seasonof 2005 at the ICRISAT station at Sadoré, Niger. The rowlength was 4.8 m with 0.75 m interrow distance and 0.4 mdistance between hills within a row. Thinning was doneto 2 plants per hill. Multiplication of materials wasperformed by controlled sibbing within each accession,aiming at a minimum effective population size (Ne) of 60plants contributing to the next generation. This limit wasset to avoid inbreeding and random loss of diversity underthe given budgetary constraints. With self-fertilizationexcluded, the inbreeding rate in small populationsfollows the equation ∆F = 1/(2Ne+1) (Falconer 1989).With the limit set at Ne = 60, the expected inbreeding ratewould be ∆F = 1/121 = 0.0083, which was consideredacceptable. For regeneration of highly-outbreeding, open-pollinated cultivars of carrot (Daucus carota L.), Le Clercet al. (2003) had recommended an effective populationsize of only 50 plants. Pollen donors were simultaneouslyselfed to obtain S1 seed of each accession for linedevelopment. Simultaneously with the multiplication, theaccessions were preliminarily characterized for days to50% flowering, plant height, panicle length, circumference,exsertion, form and compactness of the panicle, yield persibbed panicle, 1000-grain weight, and grain color.Results and DiscussionSeed multiplication. Out of the 281 accessions, 12 werecompletely lost due to lack of germination or severedowny mildew attack, and others had too few plants toassure proper multiplication. Seed multiplication throughsibbing was finally achieved for 248 accessions, with theamount of seed produced ranging from 22 g to 2474 g.The effective population size of Ne ≥60 was achieved inonly 117 accessions (minimum of 30 sibbed panicles).Twenty-five accessions were multiplied to an effectivepopulation size of less than 20 (<10 sibbed panicles) dueto poor germination or lack of adaptation of theaccessions. An increase of the inbreeding coefficient by0.02 to 0.2 units has to be noted for these accessionswhen further used. Selfed seed was produced from 240accessions with the seed quantities obtained ranging from14 g to 2901 g.Initial characterization. The pearl millet accessionsrevealed wide ranges for all the phenotypic traits assessed(Table 1) and are therefore a most valuable source ofvariation for specific breeding objectives. Frequencydistributions of the accessions were normal for plantheight but skewed for most other traits (data not shown).Accessions from Benin, Burkina Faso, Cameroon andMali showed particularly large ranges for days to 50%flowering (at least 95 days, difference between the earliestand the latest flowering accession). Accessions fromNiger revealed the widest range for panicle length (91 cmdifference between accessions with the shortest and thosewith the longest panicle).ISMN 47, 2006 111b) Panicle length (cm) a) Days to 50% flowering (d) Figure 1. Geographic differentiation of West and Central African pearl millet landraces for (a) days to 50% flowering and (b) paniclelength.112 ISMN 47, 2006Geographic differentiation. Linking the phenotypicobservations to the geographic origin of the pearl milletaccessions revealed patterns of geographic differentiationmainly for days to 50% flowering and panicle length (Fig. 1).Days to 50% flowering was correlated to latitude (coefficientof correlation r = −0.61, significant at P = 0.01), reflectingthe predominance of early-flowering accessions in thenorth and later-flowering accessions in the south (Fig. 1a).This differentiation corresponds to the increasing amountof rainfall from north to south, which results in increasingthe length of the life cycle of the cultivated landraces.Geographic differentiation for panicle length revealedtwo groups: (1) accessions originating from western Niger,northeastern Benin, northern Burkina Faso and Senegalwith generally longer panicles; and (2) accessions originatingfrom eastern Niger, western Benin, Cameroon, CentralAfrican Republic, southern Burkina Faso and Mali withoverall shorter panicles. These results confirm earlierobservations by Bono (1973) and Marchais (1982) whoequally divided West African pearl millets into two mor-phologically different groups, one comprising accessionsfrom Mali, Mauritania and Burkina Faso, and the secondfrom Niger and Senegal.Future plans. The materials have been complementedwith further accessions multiplied in the off-season of2005/2006 (less well-characterized because of large off-season effects on phenotypes), including landraces fromNigeria, Chad and Sudan which were missing in ourstudy. Small amounts of the regenerated seed werereturned to IRD and ICRISAT genebanks for furtherlong-term conservation. But the main part of the seedproduced from a total of 424 accessions (including off-season multiplication) will be exploited in multilocationdiversity analysis and heterotic grouping of West Africanpearl millet genetic resources. A three-year project(2006–2009) funded by the Federal Ministry for EconomicCooperation and Development, Germany (BMZ) hasstarted to work on these aspects since April 2006.Besides enhancing access to and use of local diversity byNARS colleagues in Senegal, Mali, Burkina Faso, Nigerand Nigeria, this project strives toward a more systematicand efficient, regionally coordinated use of diversity inbreeding open-pollinated and hybrid cultivars of pearlmillet in West Africa. Inbred lines are also being developedout of the selected accessions to widen the genetic basefor potential pearl millet hybrid development based onWest African adapted materials. Further information andseed samples of the multiplied accessions may be obtainedfrom the corresponding author.Acknowledgment. The authors would like to thank AdamouAmadou, Ada Abarchi, Djingri Lankoande and HalarouSalha for their excellent technical assistance. This study wasfinanced through ICRISAT core funds.ReferencesBono M. 1973. Contribution à la morphosystématique desPennisetum annuels cultivés pour leur grain en Afrique occidentalefrancophone. In Fr. L’Agronomie Tropicale 28(3):229–356.Falconer DS. 1989. Introduction to quantitative genetics. 3rdedn. Essex, UK: Longman Scientific and Technical.Le Clerc V, Briard M, Granger J and Delettre J. 2003.Genebank biodiversity assessments regarding optimal samplesize and seed harvesting techniques for the regeneration of carrotaccessions. Biodiversity and Conservation 12:2227–2236.Marchais L. 1982. La diversité phénotypique des milspénicillaires cultivés au Sénégal et au Mali. In Fr. L’AgronomieTropicale 37:68–80.Table 1. Mean values of 269 West and Central African pearl millet accessions and minimum and maximum observed values1for different traits evaluated at ICRISAT-Sadoré, Niger, rainy season, 2005.Trait Mean Minimum MaximumDays to 50% flowering 89 40 155Seedling vigor (1–9 scale)2 2 1 7Plant height (cm) 274 153 405Panicle length (cm) 43 18 115Panicle diameter (cm) 2 1 6Panicle exsertion (cm) −3 −23 13Grain weight per pollinated panicle (g) 22 1 781000-grain weight (g) 9 4 141. No statistics indicated here because materials were grown without replication with the main objective of multiplying them to a sufficientlylarge population size.2. 1–9 scale for seedling vigor: 1 = excellent, 3 = good, 5 = medium, 7 = poor and 9 = very poor.

Multiplication and preliminary characterization of west and central African pearl millet landraces

http://oar.icrisat.org/1130/1/ISMN-47_110-112_2006.pdf

Multiplication and preliminary characterization of west and central African pearl millet landraces

Abstract

Similar works

Full text

Available Versions

ICRISAT Open Access Repository