SORGHUM HEAD BUG INFESTATION AND MOULD INFECTION ON THE GRAIN QUALITY OF SORGHUM IN NORTHERN GHANA

Abstract

Sorghum ( Sorghum bicolor ) panicle is reported to be attacked by a myriad of insect pest species, whose infestation predisposes the grains to fungal infection, thereby compromising their quality. A complex of bugs has been reported to infest sorghum, thereby affecting quality of grains in West Africa. The objective of this study was to investigate the effect of head bug ( Eurystylus oldi (POPPIUS) infestation and mould infection on sorghum grain quality. An experiment consisting of eight sorghum breeding lines (two parental checks and six F8 derivatives), was carried out in fields at three Agro-ecological Zones (Nyankpala, Damongo and Manga) in Northern Ghana. Results showed that damage caused by head bug populations per panicle were not significant (P>0.05). Head bug damage was, however, found to be highly correlated with panicle grain mould ratings (PGMR) at all three locations. This points to the significant roles head bug damage plays in fungal infection of sorghum grains. The derivatives, on the other hand, suffered less PGMR than the compact headed Kapaala, across the three locations. The three dominant fungi isolated at Manga and Nyankpala included those of the genera Curvularia sp. (31.6 and 31.4%, respectively), Fusarium sp. (22.3 and 27.6%, respectively) and Thielaviopsis sp. (20.3 and 20.9%, respectively). At Damongo, Fusarium sp. (29.6%), Curvularia sp. (23.6%) and Mucor sp. (17.2%) were dominant. Grain quality, in terms of head bug and mould damage ratings, showed the following lines emerging superior at Manga (SARSORG-MRG-2011-3, SARSORG-SBG-2011-5 and SARSORG-SRG-2011-6), at Damongo (SARSORG-TRG-2011-1, SARSORG-SBG-2011-5 and SARSORG-MBG-2011-4) and at Nyankpala (SARSORG-MBG-2011-4, SARSORG-MRG-2011-3 and SARSORG-TRG-2011-1) and; thus suggest they may possess some desirable traits for which they could be selected for further improvement.La panicule du sorgho ( Sorghum bicolor ) a \ue9t\ue9 rapport\ue9e d\u2019\ueatre attaqu\ue9e par une multitude d\u2019esp\ue8ces d\u2019insectes pestes, dont l\u2019infestation pr\ue9dispose les grains \ue0 l\u2019infection des champignons, par cons\ue9quent compromet leur qualit\ue9. Un complexe de punaises a \ue9t\ue9 rapport\ue9 d\u2019infester le sorgho, donc affecte la qualit\ue9 des grains en Afrique de l\u2019Ouest. L\u2019objectif de cette \ue9tude \ue9tait d\u2019investiguer l\u2019effet de l\u2019infestation des punaises de t\ueate ( Eurystylus oldi , POPPIUS) et des moisissures sur la qualit\ue9 des grains du sorgho. Une exp\ue9rimentation comportant huit lign\ue9es am\ue9lior\ue9es du sorgho (deux contr\uf4les parentaux et six F8 d\ue9riv\ue9es), \ue9tait conduite au champ en trois zones agro-\ue9cologiques (Nyankpala, Damongo et Manga) au Nord du Ghana. Les r\ue9sultats ont montr\ue9 que les dommages caus\ue9s par les populations de punaises de t\ueate sur la panicule n\u2019\ue9taient pas significatifs (P>0,05). Le dommage de la punaise de t\ueate \ue9tait, toutefois, retrouv\ue9 hautement corr\ue9l\ue9 avec les scores de panicule de grains moisies (PGMR) \ue0 toutes les trois locations. Ceci montre le r\uf4le significatif que joue la punaise de t\ueate dans l\u2019infection fongique des grains du sorgho. Les d\ue9riv\ue9es, d\u2019autre part, ont souffert moins de PGMR que le Kapaala \ue0 t\ueate compacte, \ue0 travers les trois locations. Les trois champignons dominants isol\ue9s \ue0 Manga et Nyankpala comprennent ceux du genre Curvularia sp. (31,6 et 31,4%, respectivement), Fusarium sp. (22,3 et 27,6%, respectivement) et Thielaviopsis sp. (20,3 et 20,9%, respectivement). A Damongo, Fusarium sp. (29,6%), Curvularia sp. (23,6%) et Mucor sp. (17,2%) \ue9taient dominants. La qualit\ue9 du grain, en termes des scores du dommage de punaise de t\ueate et des moisissures, a montr\ue9 que les lign\ue9es suivantes \ue9taient sup\ue9rieures \ue0 Manga (SARSORG-MRG-2011-3, SARSORG-SBG-2011-5 et SARSORG-SRG-2011-6), \ue0 Damongo (SARSORG-TRG-2011-1, SARSORG-SBG-2011-5 et SARSORG-MBG-2011-4) et \ue0 Nyankpala (SARSORG-MBG-2011-4, SARSORG-MRG-2011-3 et SARSORG-TRG-2011-1) et\ua0; donc sugg\ue8re qu\u2019ils pourraient poss\ue9der quelques traits d\ue9sirables pour lesquels ils pourraient \ueatre s\ue9lectionn\ue9s pour une meilleure am\ue9lioration