Variation in susceptibility of 'Grand Naine' (AAA) to Colletotrichum musae, one of the causal agents of crown rot, in relation to fruit position in the bunch
Crown rot, caused by a parasitic complex, is one of the main post-harvest diseases affecting bananas. Colletotrichum musae is often regarded as one of the most prevalent fungi contributing to the crown rot complex. Geographical and seasonal variations in symptom expression have been observed for disease caused by C. musae. It has been suggested that this phenomenon results partially from variations at the level of fruit quality potential. Quality potential is controlled by a physiological component, but also by a parasitic component, which appears as the level of banana contamination. The physiological component of the fruit quality potential determines fruit susceptibility, i.e. the response of the fruit to inoculum pressure. For better knowledge of the mechanisms influencing fruit susceptibility to crown rot, the within-bunch variability of fruit susceptibility was evaluated. For this, one bunch per week reaching 900 degree-days (dd) as calculated by the method of Ganry (1978) was harvested at the Diadia station (PHP, Njombé, Cameroon) over a 10-week period. Bunches harvested were equivalent in size with no observable defects. Hands were numbered from 1 to 8 according to their order of appearance on the bunch (hand 1: top of the bunch, hand 8: bottom of the bunch, near the final bud). The susceptibility of each hand was evaluated. Statistical test showed highly significant (p<0.001) within-bunch variability in fruit susceptibility to C. musae. The fruits of hands 1 to 3 showed statistically the same susceptibility and appeared as the most susceptible, with an internal necrotic surface (INS) average of 138.3 mm2. The second statistical group comprised the fruits of hands 4 to 8 and had an INS average of 87 mm2. A strict linear correlation (R=0.95) was observed between INS and hand position in the bunch.
| Main Authors: | , , |
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| Format: | conference_item biblioteca |
| Language: | eng |
| Published: |
Cirad
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| Subjects: | H20 - Maladies des plantes, J11 - Manutention, transport, stockage et conservation des produits d'origine végétale, Musa, banane, Colletotrichum, anthracnose, facteur du milieu, développement biologique, fruit (botanique), récolte, http://aims.fao.org/aos/agrovoc/c_4993, http://aims.fao.org/aos/agrovoc/c_806, http://aims.fao.org/aos/agrovoc/c_1761, http://aims.fao.org/aos/agrovoc/c_481, http://aims.fao.org/aos/agrovoc/c_2594, http://aims.fao.org/aos/agrovoc/c_921, http://aims.fao.org/aos/agrovoc/c_3119, http://aims.fao.org/aos/agrovoc/c_3500, |
| Online Access: | http://agritrop.cirad.fr/542556/ http://agritrop.cirad.fr/542556/1/document_542556.pdf |
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| Summary: | Crown rot, caused by a parasitic complex, is one of the main post-harvest diseases affecting bananas. Colletotrichum musae is often regarded as one of the most prevalent fungi contributing to the crown rot complex. Geographical and seasonal variations in symptom expression have been observed for disease caused by C. musae. It has been suggested that this phenomenon results partially from variations at the level of fruit quality potential. Quality potential is controlled by a physiological component, but also by a parasitic component, which appears as the level of banana contamination. The physiological component of the fruit quality potential determines fruit susceptibility, i.e. the response of the fruit to inoculum pressure. For better knowledge of the mechanisms influencing fruit susceptibility to crown rot, the within-bunch variability of fruit susceptibility was evaluated. For this, one bunch per week reaching 900 degree-days (dd) as calculated by the method of Ganry (1978) was harvested at the Diadia station (PHP, Njombé, Cameroon) over a 10-week period. Bunches harvested were equivalent in size with no observable defects. Hands were numbered from 1 to 8 according to their order of appearance on the bunch (hand 1: top of the bunch, hand 8: bottom of the bunch, near the final bud). The susceptibility of each hand was evaluated. Statistical test showed highly significant (p<0.001) within-bunch variability in fruit susceptibility to C. musae. The fruits of hands 1 to 3 showed statistically the same susceptibility and appeared as the most susceptible, with an internal necrotic surface (INS) average of 138.3 mm2. The second statistical group comprised the fruits of hands 4 to 8 and had an INS average of 87 mm2. A strict linear correlation (R=0.95) was observed between INS and hand position in the bunch. |
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