1995. Etude du comportement et des pos­ sibilités d'introduction de nouvelles variétés de sor

ghos photosensibles en zone Cmdt dans le secteur de

Kadiolo. ·Mémoire de fin d'étude lpr de Katibougou,

Mali, 37 p.

GIRAUDY F., 1995. Annuaire statistique 94/95 -Résultats de l'enquête agricole permanente. Cmdt/Dpcc, Bamako, Mali, 14 p.

KAMATE A., 1996. Etude du comportement et des possibilités d'introduction de nouvelles variétés de sorghos photosensibles en zone Cmdt dans le.secteur de Kimparana. Mémoire de fin d'étude lpr de Kati­ bougou, Mali, 42 p.

MAÏGA A., 1 996. Etude du comportement et des pos­ sibilités d'introduction de nouvelles variétés de sor­ ghos photosensibles en zone Cmdt dans le secteur de M'Pessoba. Mémoire de fin d'étude lpr de Kati­ bougou, Mali, 39 p.

OUMAR 1., 1995. Etude du comportement et des pos­ sibilités d'introduction de nouvelles variétés de sor­ ghos photosensibles en zone Cmdt dans le secteur de

Koumantou. Mémoire de fin d'étude lpr de Kati­

bougou, Mali, 35 p.

SANAGO O., 1996. Etude du comportement et des possibilités d'introduction de nouvelles variétés de sorghos photosensibles en zone Cmdt dans le secteur de Koumantou. Mémoire de fin d'étude lpr de Kati-bougou, Mali, 44 p.

SANGARE D., 1996 . . Etude du comportement et des possibilités d'introduction de nouvelles variétés de sorghos photosensibles en zone Cmdt dans le secteur de Konobougou. Mémoire de fin d'étude lpr de Kati­ bougou, Mali, 40 p.

TRAORE S., 1995. Etude du comportement et des possibilités d'introduction de nouvelles variétés de sorghos photosensibles en zone Cmdt dans le secteur

de Dioïla. Mémoire de fin d'étude lpr de Katibougqu,

Mali, 55 p.

OUATTARA M., VAKSMANN M., REYNIERS F.N., NIANGADO O., KOU RESSY M., 1997. Diversité phénologique des sorghos du Mali et adaptation à la diversité des agro-systèmes - Mise en valeur d'un savoir. Rencontre internationale « Gestion des res­ sourcés génétiques des plantes de savanes, 21-28 février 1997, Bamako, Mali , p. 73-84.

O.S. MURTY

RATNADASS A., CHANTEREAU J. GIGOU J. (éditeurs), 1 998.

Amélioration du sorgho et de sa culture en Afrique de l'Ouest et du Centre.

Actes de l'atelier de restitution du programme conjoint sur le sorgho lcrisat-Cirad,

1 7-20 mars 1 997, Bamako, Mali.

Collection Colloques, Montpellier, Cirad-ca, 3 1 5 p.

lcrisat (International Crops Research lnstitute for the Semi-Arid Tropics), BP 320, Bamako, Mali

R. lABO

lcrisat (International Crops Research lnstitute for the Semi-Arid Tropics), PMB 3491 , Kano, Nigeria

Abstract - Regional trials conducted in West and Central Africa (Wca) during 1 986-1 995 showed that sorghum hybrids had higher grain yields (38% yield advantage) and stability than pure line varieties. Regression analysis of yield showed that the selected hybrids maintained their yield superiority consistently across low and high yielding environments over years. There is a scope for further improvement of hybrids adapted to Wca through breeding male and female parents with Wca germplasm. ln agronomie studies conducted during 1 990-1 992 across three different agroecological zones, hybrids exhibited, on average, grain yield advantage of 28 to 60% over the pure line variety and had higher harvest indices. Hybrids such as lcsh 89002 Ng, lcsh 89009 Ng, and lcsh 507 responded more to increased nitrogen and plant density than pure line varieties. "These hybrids performed well also when intercropped with legumes such as groundnut, ·cowpea, soy­ bean and pigeonpea. On-farm tests in collaboration with national programs in Wca gave encouraging results, but more detailed studies in conjunction with Integrated Pest Manage­ ment (1pm) practices are required. ln order to ensure that the hybrid technology is adopted by farmers in 1his region, thereby increasing sorghum productivity, there is a need to establish commercial production of hybrid seeds and to enhance the availability of other inputs, particularly fertilizer.

Résumé - Les potentialités des sorghos hybrides en Afrique de l'Ouest et du Centre. Les essais régionaux conduits en Afrique de l'Ouest et du Centre durant les années 1 986-1 995 ont montré que les hybrides de sorgho ont un rendement et une stabilité du rendement supérieurs aux lignées fixées. Une analyse de régression de rendem@t a également montré que les hybrides sélectionnés ont maintenu leur supériorité de ren­ dement sur plusieurs années et sous différentes conditions d'environnement. Des possibilités d'amélioration d'hybrides adaptés à l'Afrique de l'Ouest et du Centre sont envisageables par la sélection de parents mâles et femelles avec le germo­ plasme ouest et centrafricain. Au cours des études agrono­ miques, conduites de 1 990 à 1 992 dans trois zones écolo­ giques différentes, les hybrides ont présenté des index de récolte meilleurs et des rendements moyens de 28 à 60 % supérieurs aux lignées pures. Les hybrides tels que lcsh 89002

Ng, lcsh 89009 Ng et lcsh 507 fournissent une meilleure réponse à un apport d'azote et à une densité élevés que les variétés pures. Ils sont également bien adaptés aux associations culturales (avec des légumineuses telles que arachide, niébé, soja ou pois d' Angole). Les résultats des tests en milieu paysan, menés en collaboration avec les instituts nationaux, sont encourageants mais des études en liaison avec les programmes de lutte intégrée doivent être poursuivies. Pour favoriser l'adoption par les paysans de ces nouvelles variétés et par conséquence accroître la productivité du sorgho, il est néces­ saire d'organiser la production commerciale de semences et de faciliter l'accès aux intrants et en particulier desiertilisants.

Sorghum productivity in West and Central Africa (Wca) has remained well below 1 t/ha compared to 4 to 5 t/ha in North America and .Europe for the last three decades (lcrisat/Fao 1 996). The reason for this large difference is essentially the degree of commer­ cialization and adoption of new technologies. One important factor underlying sorghum yield increases in the developed as well as developing countries such as Usa and Mexico is the adoption of hybrids. However in Wca, most of the sorghum is produced on smal l farms using land races, sometimes inter­ cropped, and frequently in areas where soil fertility is low and rainfall distribution is poor.

The advantages and stability of sorghum hybrids over pure line varieties even in bad years in eastern Africa has been documented (Doggett, 1 988). ln Wca, studies on sorghum hybrids conducted by Andrews (1 975), Chantereau (1 983) and Kapran (1 988) showed the high potential of hybrids, but the need for· more intensive studies across a wide range of environments in compai:i son with varieties and an evaluation of suitable cropping and management systems for hybrids was recognized. Currently, there are only a few national programs in Wca engaged in

hybrid evaluation: Niger, Nigeria and Burkina Faso. Recently hybrids have been formai ly released in Nigeria and Niger and it is tao early to assess their impact. lcrisat has been experimenting with sorghum hybrids in Wca since 1 986 in collaboration with the national programs as well as the West and Central Africa sorghum research network (Wcasrn).

There were several objectives of these experiments with sorghum hybrids:

- to evaluate the productivity and stability of hybrids in comparison with bath improved and local varie­ ties;

- to identify suitable female (Cms) and male parents among those avai lable from various sources;

- to quantify the heterotic response of the hybrids over parents;

- to assess the total d_ry matter partitioning in hybrids compared to improved varieties and local land races; - to determine the optimum plant density and fertility levels for hybrids in comparison with varieties; - to investigate the suitability of hybrids in the inter­ cropping systems with legumes.

The following sections summarize the important results obtained in some of the experiments conducted over the last ten years.

1 Hybrid yield superiority

Ten to 30 hybrids were evaluated in the West African sorghum hybrid adaptation trials (Washat) at 6 to 1 3 locations each year during 1 986-1 995 using improved varieties as well as local contrais. Average grain yield of the top ranking hybrids across locations in the 87 tests was 3.59 t/ha which was 38% superior to the best variety contrai average (2.60 t/ha, table 1). The local contrais, which were frequently late matu­ ring (and variable across locations), were the poorest yielders in all the years. Grain yields of the best

hybrids in individual tests were as high as 6 t/ha in some years. Regression analyses of the multiloca­ tional data each year and across years for some selected hybrids showed that hybrids such as lcsh 507 (lcsa 38 x Mr 926) maintained their yield super­ iority consistently across low and high yielding envi­ ronments in all the years. Encouraging results were also obtained in farmers' managed on-farm trials in Kano and Jigawa states in northern Nigeria during 1 991 and 1 992. Average grain yields from 2 1 trials grown in these two states ranged from 1 .24 to 1 .35 t/ha for hybrids as compared to 1 .07 t/ha for the farmers' variety. Similar work is in progress inj3urki['a Faso and Mali in cooperation with the Institut national d'études et de recherche agricoles (lnera) and la Compagnie malienne pour le développement des textiles (Cmdt), respectively.

1 Hybrid parents

A range of female (A 1 Cms) and male parents bred at lcrisat Asia Center and also several from Texas A & M University were evaluated over the years in Nigeria, Mali and Burkina Faso. Important female parents identified include lcsa/B 38, lcsa/B 39, lcsa/B 41 , lcsa/B 42, Tx NB 631 , Tx NB 8606, etc. Ali these are of exotic and zerazera origin and have good grain quality and adequate levels of disease resistance. Similarly the male parents in use are also of zerazera origin. Currently available elite hybrids in Wca are thus based on parents bred elsewhere but found to be acceptable in Wca. However, hybrids based on exotic x Wca local derived parents could exhibit improved local adaptation and advantage and are therefore required in the future. Moreover, the exotic parents are ail early maturing (< 75 days to 50% flo­ wering) and there is a need to diversify the range of maturity among hybrid parents to enable production of hybrids required in higher rainfall zones.

Table 1. Mean grain yields (t/ha) of top ranking hybrids and variety contrais in West African sorghum hybrid

adaptation trials (Washat), 1 986-1 995.

Year Locations n

.

1 986 1 2 lcsh 143 3.22 Framida 2.43 1 987 1 0 lcsh 643 2.97 Framida 1 .77 1 988 7 lcsh 507 3.31 lcvs 111 2.56 1 989 8 lcsh 507 3.66 lcvs 1 1 1 2.97 1 990 8 lcsh 89002 Ng 3.71 lcvs 1 1 1 2.08 1 991 1 3 lcsh 89009 Ng 3.40 lcvs 1 1 1 2.70 1 992 6 lcsh 89009 Ng 4.34 lcvs 1 1 1 3.02 1 993 8 lcsh 507 4.30 lcvs 1 1 1 3.1 2 1 994 8 lcsh 89009 Ng 3.46 lcvs 1 1 1 2.70 1 995 7 lcsh 507 3.56 lcvs 1 1 1 2.63

Mean Hybrid 3.59 Variety 2.60

1 Heterosis

Male and female parents of three hybrids along with their corresponding hybrids and three pure line varieties including the local contrai were evaluated for their phenological and yield performance in a replicated trial at Bagauda in 1992. On the average, the hybrids outyielded their male parents by 26% and their female parents by 53%. The hybrids produced an average total dry matter of 13.41 t/ha which was 9% higher than that of the male parents and 26% higher than that of the female parents. The hybrids yielded 6.60 t/ha of grain as compared to 5.23 and 4.29 t/ha for their male and female parents, respecti­ vely.

1 Harvest index

Agronomie experiments conducted at Bagauda in l990 showed that under terminal drought the har­ vest index of the sorghum hybrid lcsh 507 was superior to 26 land races included in the study under all the 5 planting dates (commencing with the rainy season) and the hybrid outyielded the local races (lcrisat, 1991 ).

Two sorghum hybrids (lcsh 507 and lcsh 89002 Ng) were studied in comparison with an early maturing variety (lcvs 247) and a late maturing local variety (Samsorgh 14) for ·their performance in replicated experiments conducted in the rainy season over five years at Bagauda, Nigeria (table 11). The average harvest index (Hi) of the hybrids was 0.39 to 0.41 while that of the early maturing variety was 0.34 compared to 0.18 for the late maturirrg local contrai. The early maturing -hybrid, lcsh 89002 Ng produced an average of 10.86 t/ha of total dry matter as compared to 12.36 t/ha of the late maturing local variety. The average grain yield of the hybrid was 4.20 t/ha while that of the local variety was 2.23 t/ha.

1 Plant density and nitrogen

Field trials were conducted at (Bagauda, Minjibir and Samaru) in northern Nigeria to evaluate the per­ formance of three hybrids (lcsh 507, lcsh 89002 Ng, and lcsh'-89009 Ng) in comparison with a late matu­ ring contrai variety (Samsorgh 14) at two plant densi­ ties (5.3 and 10.6 plants/m2) and four nitrogen levels . (0, 45, 90 and 135 kg N/ha). The hybrids exhibited, on average, grain yield advantage of 28 to 60% over the check variety which produced more total dry matter and larger grains than the hybrids. Cultivar �es­ ponse to plant density and nitrogen level varied from year to year and was influenced by rainfall. ln wet

years, optimal density was 10.6 plants/m2 but in dry

years it was 5.3 plants/m2. Maximum grain yields

were obtained at 90 kg N/ha (lcrisat, 1991, 1992, 1993). 5imilar studies were done at Samanko, Mali during 1996 and the same trends were obtained.

l lntercr�pping systems

lntercrop experiments involving sorghum hybrids with legumes such as groundnut, cowpea, soybean and pigeonpea were conducted at Bagauda, Nigeria during 1990 to 1993 (lcrisat, 1991; 1992; 1993; 1994). The hybrids performed as well or better than the early maturing pure line variety and the late maturing local variety as indicated by their higher grain yields. Land equivalent ratios were_ also found greater with hybrids in these intercropping systems than with pure line varieties.

1 1 ntegrated pest management

. . practices

Grain quality of sorghum hybrids can be affected by head bugs (Eurystylus oldi) in some seasons and

Table 11. Mean grain yield (t/ha), total dry matter (t/ha) and harvest index of sorghum cultivars observed at Bagauda, Nigeria 1 989-1 993(1!.

Cultivar Time to 50% flowering (d.) Grain yield Total d_ry matter Harvest I ndex

lcvs 247 71 3.37 9.86 0.34

Samsorgh-1 4

(Local contrai) 93 2.23 1 2.36 0.1 8

lcsh 507 65 4.37 1 0.56 0.41

lcsh 89002 NG 71 4.20 1 0.86 0.39

(1)Based on agronomie experimental data averaged over five years for lcvs 247 and Samsorgh-14 and over four years for lcsh 507 and lcsh 89002 Ng.

locations. We evaluated the performance of a hybrid, lcsh 89009 Ng and two pure line varieties including a local variety (Gaya early) under unprotected and pro­ tected conditions at two dates of planting and two nitrogen levels during 1995 and 1 996 at Bagauda and Samaru, Nigeria. The hybrid outyielded the varieties under protected as well as unprotected conditions. On farm studies on the population dynamics of

E. oldi in hybrid sorghum are under way.

1 Conclusions

The super�or performance of sorghum hybrids over pure line varieties was demonstrated in various trials conducted over years and across different agroecological zones in West and Central Africa. Overall, the grain yield advantage of the hybrids over the pure line varieties ranged from 28 to 60%. The hybrids had higher harvest indices and were more responsive to increased plant density and nitrogen level than varieties. The hybrids performed well in intercropping systems involving legumes such as groundnut, cowpea, soybean and pigeonpea. The potential of the hybrids could be better exploited in the Sudanian zones (600 - 1 000 mm rainfall) and more specifically in the Sofitex or Cmdt areas in Bur­ kina Faso and Mali where the residual fertilizers applied to cotton are available for exploitation. On­ farm studies, in collaboration with the Nars partners, are needed to gather additional information on the performance of these hybrids under the farmers' levels of management and taking into account various. integrated pest management practices. Seed

2 1 4

availability is crucial to sorghum hybrid production and it is therefore essential to establish good hybrid seed production and distribution infrastructures. Other inputs such as fertilizer also should be made available to the farmers to ensure that the potential of the hybrids is fully exploited.

References

ANDREWS D. J., 1975. Sorghum grain hybrids in Nigeria. Experimental Agriculture 11: 11 9-1 27. CHANTEREAU J., 1983. Sélection d'hybrides de sorgho pour le Centre-nord et le nord du Sénégal. L'Agronomie Tropicale 38 (4) : 295-302.

DOGGETI H., 1988. Sorghum, 2nd edition. Tropical Agriculture series. Harlow, U.K. Longman, 512 p. ICRISAT, 1991 . lcrisat West African Programs Annual Report 1991. Niger, lcrisat Sahelian center.

ICRISAT, 1992. lcrisat West African Programs Annual Report 1992, Niger, lcrisat Sahelian center.

ICRISAT, 1993. lcrisat West African Programs Annual Report 1993, Niger, lcrisat Sahelian center.

ICRISAT 1 994. lcrisat West African Programs Annual Report 1994, Niger, lcrisat Sahelian center.

ICRISAT/FAO, 1996. The world sorghum and millet economies. Facts, trends and outlook. lcrisat, lndia, 68 p.

KAPRAN 1., 1 988. Evaluation of the agronomie