+Bioline International Official Site (site up-dated regularly)

African Crop Science Journal, Vol. 9. No. 3, pp. 481-486

AGRONOMIC PERFORMANCE OF IITA'S IMPROVED MUSA GERMPLASM AT CRBP, NJOMBé, CAMEROON

P. NOUPADJA and K. TOMEKPÉ

CRBP, P.O. Box 832 Douala Cameroon

Received 20 Septeber, 1999
Accepted 17 October, 2000

Code Number: cs01067

Abstract

Black Leaf Streak Disease (BLSD) constitutes one of the major biological threats to plantain and banana production in sub-Saharan Africa, where over 100 million people rely on these crops for their food energy. In order to overcome this constraint, IITA (International Institute of Tropical Agriculture) developed resistant germplasm that has been evaluated in various production areas in Africa. Six of these hybrids (TMPx 7002-1, TMPx 1621-1, TMPx 4479-1, TMPx 7152-2, TMBx 1378 and TMBx 5295-1) recently made available through the INIBAP Transit Center (ITC), were evaluated in the climatic conditions of CRBP-Njombé (Cameroon) for their agronomic performance and their response to the disease. The trial consisted of a randomised complete block design with 2 replicates of 10 plants per hybrid. Observations were carried out for two production cycles. The results showed that the plantain hybrids TMPx 1621-1 and TMPx 7002-1 performed well in Njombé, both having an average bunch weight of 17.7 kg. In terms of yield potential, TMPx 7002-1 outyielded TMPx 1621-1 because of its shorter growth cycle. The very precocious cooking banana hybrid TMBx 5295-1 (9.4 months) is highly productive with over 50 t.ha^-1 yr^-1. Reaction to black sigatoka of the hybrids tested varied from «susceptible» (S) to «highly resistant» (HR). These results emphasise the need for multilocational testing of newly bred germplasm before their release in production areas.

Key Words: Bananas, black sigatoka, IITA hybrids, plantain

Résumé

La Maladie des Raies Noires (MRN) est l'une des contraintes majeures à la production des bananes et des plantains qui constituent une importante source alimentaire pour plus de 100 millions de personnes en Afrique au sud du Sahara. De nombreux hybrides résistants à cette maladie ont été créés par le programme d'amélioration génétique des bananiers de l'IITA et évalués dans plusieurs localités de la région. Six de ces hybrides (TMPx 7002-1, TMPx 1621-1, TMPx 4479-1, TMPx 7152-2, TMBx 1378 et TMBx 5295-1) récemment mis à disposition par l'INIBAP après indexation virale ont été évalués dans les conditions climatiques de Njombé (Cameroun) pour leurs performances agronomiques et leur réaction vis à vis de la maladie. Les hybrides ont été plantés selon le dispositif expérimental des blocs de Fisher constitués de 2 répétitions de 10 bananiers par traitement. Les observations ont été réalisées au cours des 2 premiers cycles de production. Les caractéristiques agronomiques montrent que deux hybrides de plantain, TMPx 1621-1 et TMPx 7002-1, ayant des régimes de poids moyen de 17,7 kg, se comportent mieux que les autres à Njombé. Cependant, l'hybride TMPx 7002-1 est plus productif que le TMPx 1621-1 à cause de son cycle plus court. L'hybride de banane à cuire TMBx 5295-1 qui est très précoce (9,4 mois) est très productif avec un rendement potentiel atteignant 50 kg/ha/an. Le comportement des hybrides testés vis à vis de la MRN va du phénotype S (sensible) au phénotype TR (très résistant). Ces résultats impliquent la nécessité des évaluations multilocales de matériel végétal nouvellement créé avant leur diffusion pour la production.

Mots Clés: Bananes, maladie des raies noires,hybrides IITA, plantains

INTRODUCTION

Bananas and plantains provide an important food source for over 100 million people in sub-Saharan Africa. The highest per capita consumption in the world is found in this region (INIBAP, 1999). All plantains traditionally grown by West and Central African farmers are susceptible to black leaf streak disease (BLSD), a leaf spot disease caused by the airborne fungus, Mycosphaerella fijiensis Morelet. The disease was first identified in the Fiji Islands in 1963 from where it spread to other Pacific Islands, Asia, and 10 years later to Africa and Central and South America (IITA, 1994). The spores of the fungus, dispersed by wind and water, cause leaf necrosis and sharply reduce photosynthesis. An infected plant can lose one-third to one-half of its expected yield (Stover, 1983; Mobambo et al., 1993). In 1987 IITA started a breeding program for plantains and cooking bananas to identify and develop cultivars with resistance to the disease. Many BLSD-resistant tetraploid hybrids of plantain have since been developed (Vuylsteke et al., 1993a, b) and evaluated over different agro-ecological conditions of West and Central Africa (De Cauver et al., 1995). In 1996, Crouch and Ortiz (Crouch and Ortiz, 1996) reported the availability of six IITA improved hybrids from the INIBAP Transit Center (ITC) in Belgium. This paper presents the agronomic performance and BLSD response of these hybrids evaluated under the climatic conditions of CRBP, Njombé, Cameroon.

MATERIALS AND METHODS

The trial was carried out in Njombé from April 1997 to April 1999. The climate in Njombé (4°35 N, 9°39 E) is tropical with 2 seasons: 8-months rainy season from mid-March to mid-November and 4-months dry season from mid-November to mid-March. Annual rainfall is 2,567 mm of water falling in 160 days. Annual mean temperature is 26.6°C with minimum of 21.8°C and maximum of 31.5°C. Mean relative humidity throughout the year is 82%. The soils of the experimental site are young brown soils derived from volcanic rocks. They are characterised by good texture and structure, moderate depth, rich in minerals, with a pH of 6.0 at the surface and 6.3 at 50 cm depth (Martin et Segalen, 1966).

The trial consisted of four plantain hybrids (TMPx 1621-1, TMPx 4479-1, TMPx 7002-1 and TMPx 7152-2) and 2 cooking banana hybrids (TMBx 5295-1 and TMBx 1378) (Table 1). The planting material was made up of in vitro plantlets weaned by the CRBP tissue culture laboratory after virus indexation by the INIBAP's Virus Indexing Center (VIC). These materials were planted following a randomised complete block design with 2 replicates of 10 plants per hybrid. 'French sombre', a black sigatoka susceptible plantain cultivar, was planted alongside the hybrids to provide Mycosphaerella fijiensis inoculum, but the disease incidence was not recorded on this cultivar. Plants were spaced 3 m between rows and 2 m within rows, giving a plant density of 1,667 per hectare. The plants were not chemically treated against BLSD. Other cultural practices and treatments such as fertilisation were uniformly applied to each hybrid.

Agronomic data were collected on the plant crop and the first ratoon. Plant height (PHF) was measured at flowering. The suckering behaviour as indicated by both the number of suckers (NS) with a height of more than 50 cm and the height of the tallest sucker (HTSF) was recorded at flowering. Cycle duration included days to flowering (DF), days to harvesting (DH) and fruit filling time (FFT). The total number of leaves (TNL) with a lamina broader than 10 cm was recorded until flowering. Yield components consisted of bunch weight (BW) measured in kilogrammes, number of hands (NH) and number of fingers (NF). Length (FL) and caliber (FC) of the characteristic fruit (middle finger of the external row of the fourth superior hand, measured along the internal side of the fruit) were also recorded. By using bunch weight (BW) and growth cycle (GC), yield potential (YLD) (mt ha^-1 year^-1) was obtained as YLD = (BW x 365 x 1,667) / (GC x 1,000) (5). The GC indicates the period from planting to harvesting of the first ratoon. Cultivar response to BLSD was assessed during the vegetative phase of the plant crop by recording severity of the disese on the youngest leaf spotted (YLS), the number of standing leaves at flowering (NSLF) and at harvesting (NSLH).

The data were analysed by standard analysis of variance (ANOVA) with the STATITCF statistical package. The Newman-Keuls test was used to detect significant differences between means at 5% level of significance.

RESULTS

Growth and yield characteristics. The results of growth and yield of the plant crop are shown in Table 2. Significant differences (P < 0.05) were observed for growth and yield characteristics, except for number of suckers at flowering (NS), bunch weight (BW) and number of fingers per bunch (NF). Plant height varied from 2.74 m (TMPx 7152-2) to 4.23 m (TMBx 1378). All hybrids produced 3.1 to 4 suckers at flowering with their height ranging from 1.41 m to 3.34 m. In terms of cycle duration, the banana hybrid TMBx 5295-1 with a fruit filling time of 2 months was very precocious compared to the plantain hybrids. The bunch weight varied from 13.9 kg in TMPx 7152-2 to 20 kg in TMBx 5295-1. Among the plantain hybrids, TMPx 1621-1 recorded the highest bunch weight. Cultivar TMBx 1378 produced a compact bunch with many small fingers. The fruit length was highest for hybrid TMBx 5295-1, while the fruit size of the plantain hybrids was approximately 20 cm.
In the ratoon crop (Table 3), significant differences (P < 0.05) were observed for bunch weight. The banana hybrid TMBx 1378 recorded the highest bunch weight of 30.9 kg, registering an increase of 84% compared to the plant crop. The bunch weights of the plantain hybrids were less than 20 kg. Contrary to the plant crop, TMPx 1621-1 produced smaller bunches in the second cycle. In terms of yield potential expressed in mt ha^-1 year^-1 (data not analysed statistically), TMBx 5295-1 was the best hybrid having 50 mt ha^-1 year^-1. Hybrid TMPx 7002-1 outyielded the other plantain hybrids with a yield potential of 38.6 mt ha^-1 year^-1.

Black leaf streak disease reaction. Reaction of the hybrids tested to BLSD varied from phenotype S (susceptible) to phenotype HR (highly resistant) (Table 4). While hybrids TMPx 7002-1, TMPx 4479-1, TMBx 1378 and TMBx 5295-1 showed a partial resistance (PR), TMPx 1621-1 was susceptible (S) with the lowest YLS at flowering, which is in agreement with the disease scoring by Vuylsteke et al. (1993a). TMPx 7152-2 exhibited a high resistance (HR) behaviour to BLSD, although it had only 2 standing leaves at harvest.

DISCUSSION

Several BLSD-resistant plantain and banana hybrids have been developed by IITA (Vuylsteke et al., 1993b) and some of them were registered and made available for distribution to national agricultural programs in order to be evaluated under a wide range of agro-ecological conditions prior to their release as new cultivars (Crouch and Ortiz, 1996; Vuylsteke et al., 1993a). A series of multilocational testing has been carried out at IITA and NARS sites in sub-Saharan Africa.

The best plantain hybrid in Njombé (Cameroon) in terms of yield as expressed by bunch weight was TMPx 1621-1 with an average of 17.7 kg for the two crop cycles. This hybrid has been widely tested. In a series of multilocational tests carried out in 10 environments from 1992 to 1995, the mean bunch weight recorded for this hybrid (plant crop and ratoon) was 9.6 kg (Ortiz et al., 1996) with the highest weight recorded at Mbalmayo, Cameroon (16.4 kg). This bunch weight has been confirmed by Noupadja and Tomekpe (Noupaja and Tomekpé, 1999) in a trial carried out at Mbalmayo from 1997 to 1999 (plant crop). Hybrid TMPx 7002-1 also yielded an average of 17.7 kg for the two crop cycles, but this hybrid was superior to TMPx 1621-1 because of its shorter growth cycle. A range of 9.1 to 17.5 kg was obtained for TMPx 7002-1 in other trials carried out at Ibadan (Ayodele, 1996), Ivory coast (N'Guessan et al., 1996), Ghana (Ahiekpor et al., 1996) and Onne (Ortiz et al., 1996). In an Advanced Musa Yield Trial (AMYT) performed at Limphasa in Nkhata-Bay district, Malawi (Mwenebanda and Phiri, 1998), this hybrid produced a bunch weight of 10 kg for the plant crop and 5.4 kg in the ratoon crop. The 'Bobby Tannap' hybrid 'TMPx 4479-1' performed quite well in Njombé and Mbalmayo (Noupadja and Tomekpé, 1999) compared to Onne where a bunch weight of 13.2 kg were obtained (Vuylsteke et al., 1993a,b). The Laknau-derived cooking banana hybrid 'TMPx 5295-1' with its bunch weight of more than 20 kg was very productive, but was not appreciated by consumers because of its lower pulp quality.

In the process of this evaluation, the banana streak virus (BSV) problem could not be overlooked. Symptoms of BSV were noticed on hybrids TMPx 7002-1, TMPx 4479-1, TMPx 7152-2 and TMBx 1378 even though these materials were indexed negative by the VIC. These symptoms mostly appeared during the ratoon crop, implying a long time for the virus titre to build up and express itself after in vitro culture. Since there may be activation of the virus when the planting material is processed in vitro, the question of germplasm movement has to be re-examined in view of the type of planting material to be transferred or the weaning procedure to be followed. This also raises the problem of which type of planting material should be used for evaluation trials in order to alleviate this problem. N'Guessan et al. (1996), while evaluating black sigatoka resistance of some tetraploid plantain hybrids in the pedo-climatic conditions of lowland Ivory Coast, concluded that the BSV problem was still not solved and might constitute a constraint to the release of some of these hybrids.

The results presented here show that the hybrids performed well in Njombé, Cameroon, compared to the other NARS sites in sub-Saharan Africa, probably because of good soil fertility. Their poor performance in Onne where they were developed might be due to aluminum toxicity of the soil, which causes root tip stunting and death leading to poor growth (Buddenhagen, 1996). These results emphasise the importance of multilocational testing of improved Musa hybrids in studying their performance in various environments and testing their adaptability before their release as new cultivars. It has been noticed that the hybrids performed differently across different environments. This is probably due to the influence of many enviromental factors, namely climate, soil type and disease pressure. The cultural practices applied to the planting material also has to be taken into account. These plantain hybrids are not appreciated by local producers in Njombé because of their compact bunch shape and their short finger length.

ACKNOWLEDGEMENTS

The authors are grateful to INIBAP for providing the planting material and CRBP for financial support. We also thank our field technicians Djithe E. Berthin for field managemant and agronomic observations and Wamba André for black sigatoka assessement.

REFERENCES

Ahiekpor, E.K.S., Afreh-Nuamah, K., Ortiz, R. and Ferris, R.B.S. 1996. Advanced Musa yield trial at the University of Ghana Agricultural Research Station - Kade: 1. Growth and yield parameters. In: Plantain and Banana: Production and Research in West and Central Africa. Proceedings of a Regional Workshop held at High Rainfall Station, Onne,
Rivers State, Nigeria. Ortiz, R. and M.O. Akoroda (Eds.), pp. 129-132. Published by IITA, Ibadan, Nigeria.
Ayodele, M. 1996. Advanced Musa yield trial at Moor Plantation, Ibadan. In: Plantain and Banana: Production and
Research in West and Central Africa. Proceedings of a Regional Workshop held at High Rainfall Station, Onne, Rivers State, Nigeria. Ortiz, R. and M.O. Akoroda (Eds.), pp. 132-133. Published by IITA, Ibadan, Nigeria.
Buddenhagen, I.W. 1996. Banana research needs and opportunities. In : Banana Improvement: Research Challenges and Opportunities. Persley, G.J. and G. Pamela (Eds.), The World Bank, Washington, D.C. 5 pp.
Crouch, J.H. and Ortiz, R. 1996. Availability of IITA's improved Musa germplasm. MusAfrica 9:1-2.
De Cauver, I., Ortiz, R. and Vuylsteke, D. 1995. Genotype-by-environment interaction and phenotypic stability of Musa germplasm in West and Central Africa. African Crop Science Journal 3:425-432.
IITA. 1994. International Institute of Tropical Agriculture. Annual Report 1994. 16 pp.
INIBAP. 1999. Networking Banana and Plantain: INIBAP Annual Report 1998. International Network for the Improvement of Banana and Plantain, Montpellier, France. 47 pp.
Martin, D. et Segalen, P. 1966. Notice explicative. Carte pR.B.S. dologique du Cameroun oriental au 1/1 000 000. ORSTOM, YaoundR.B.S. 133 pp.
Mobambo, K.N., Gauhl, F., Vuylsteke, D., Ortiz, R., Pasberg-Gauhl, C. and Swennen, R. 1993. Yield loss in plantain from black sigatoka leaf spot and field performance of resistant hybrids. Field Crops Research 35:35-42.
Mwenebanda, B.M.L. and Phiri, N.A. 1998. Performance of Advanced Musa Yield Trial at Limphasa in Khata-Bay District, Malawi. MusAfrica 12:5-11.
N'Guessan, A., Kobenan, K. et Kone, D. 1996. Evaluation de la résistance à la cercosporiose noire d'hybrides tétraploïdes de plantain dans les conditions pédo-climatiques de la Basse Côte d'Ivoire. In: Plantain and Banana: Production and Research in West and Central Africa. Proceedings of a Regional Workshop held at High Rainfall
Station, Onne, Rivers State, Nigeria. Ortiz, R. and M.O. Akoroda (Eds.), pp. 127-129. Published by IITA, Ibadan, Nigeria.
Noupadja, P. and Tomekpé , K. 1999. Agronomic performances of six improved IITA Musa germplasm in the agroecological conditions of Mbalmayo (Cameroon). Results of the plant crop. Document CRBP 99/177. (Infomusa, in press). 7 pp.
Ortiz, R., Vuylsteke, D., Okoro, J., Adelaja, B.A., Arene, O., Ikiedugwu F.E.O., Hemeng, O.B., Yeboah, D.K., Agbor, A.N., Nwogu, A.N., Okoro, E. and Lawrence, A. 1996. Multilocational testing of hybrid Musa germplasm at IITA and NARS sites in sub-Saharan Africa. In: Plantain and Banana: Production and Research in West and Central Africa. Proceedings of a Regional Workshop held at High Rainfall Station, Onne, Rivers State, Nigeria. Ortiz, R. and M.O. Akoroda (Eds.), pp. 115-133. Published by IITA, Ibadan, Nigeria.
Stover, R.H. 1983. Effet du Cercospora noir sur les plantains en Amérique centrale. Fruits 38: 326-329.
Vuylsteke, D., Swennen, R. and Ortiz, R. 1993a. Registration of 14 improved Musa plantain hybrids with black sigatoka

resistance. HortScience 28:957-959.
Vuylsteke, D., Swennen, R. and Ortiz, R. 1993b. Development and performance of black sigatoka-resistant tetraploid hybrids of plantain (Musa spp., AAB group). Euphytica 65:33-42.

The following images related to this document are available:

Photo images