ISSAKA Ahmadou

DEVELOPMENT OF DOWNY MILDEW RESISTANT, F1 PEARL MILLET (Pennisetum glaucum ( L.) R. Brown) HYBRIDS IN NIGER

Abstract

A Participatory rural appraisal conducted in three villages belonging to the three most favorable zones for agriculture in Niger showed that pearl millet is the dominant crop across the area surveyed. Farmers used diverse criteria for selecting millet varieties according to the environmental conditions in their locality. Resistances to Striga, head miner, downy mildew, stem borer, rainstorms, and drought; high grain yield, food quality, and earliness are the main preferred traits. Characters like spike length and compactness are needed for particular zones. Qualitative traits such as grain size and grain color were regularly mentioned by farmers, even though they appeared in low frequencies during farmers’ criteria evaluations. Pearl millet productivity should be increased particularly in the Sahelian zone where land availability constitutes a more important issue. Hybrid breeding is the most effective way to increase pearl millet productivity. Heterosis and combining ability of sixteen hybrids developed from eight locally adapted, improved and land race varieties belonging to two heterotic groups were studied. Eight hybrids: Gamoji x HKB, Ex-Borno x H80-10Gr, Moro x HKP-GMS, Ankoutess x HKB, Ankoutess x HKP-GMS, Ankoutess x Souna-3, Gamoji x Souna-3, and Ex-Borno x HKB outyielded the check which in turn performed better than the best parent Souna-3. Variety HKB had the best GCA for grain yield. The hybrid between Gamoji and HKB had the highest SCA and the best mid-parent heterosis for grain yield. There was a good association between GCA, SCA and heterosis for increased yield in the hybrid. Increased yield was found to be positively and highly correlated with peduncle girth while it was negatively correlated with the number of days to flowering. Hybrids showed more phenotypic uniformity than their parents. There were interactions between genotype and environment. Downy mildew is the most important disease of pearl millet; resistance to the pathogen is required to guarantee a stable harvest. Pot-grown seedlings of the above eight parents and the sixteen hybrids plus seven checks were inoculated with four isolates of Sclerospora graminicola under glass house conditions at ICRISAT-Sadoré. The isolates collected from different fields in Niger were different from each other. The isolate from Maradi showed the highest level of pathogenicity. Twelve hybrids: Ankoutess x Souna-3, Ex-Borno x Souna-3, Ankoutess x HKB, Ex-Borno x HKB, Ex-Borno x HKP-GMS, Gamoji x HKB, Gamoji x HKP-GMS, Gamoji x H80-10Gr, Gamoji x Souna-3, Moro x HKB, Moro x HKP-GMS, and Moro x Souna-3; and 6 parents: Ankoutess, Ex-Borno, Gamoji, Moro, HKB, and H80-10Gr; were resistant over the 4 isolates with a mean disease incidence less than 10%. The inheritance of the resistance was dominant to additive, dominant to recessive, additive, and completely recessive for the Liboré, Sadoré, Tara, and Maradi isolates; respectively. Besides being dominant, additive or recessive; epistatic effects affected the inheritance of the resistance. Cytoplasmic male sterile versions were obtained with seven parents among the eight. The varieties with high rate of sterilization could be considered those having the most stable sterility.