DR. ISSAKA AHMADOU

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

With rapid population growth, continued improvement for yield of pearl millet, the first staple cereal in Niger, is a major priority. It is also necessary to integrate local community needs in technology development through exploitation of their knowledge.

Hence a participatory rural appraisal was conducted in three villages, in order to obtain the farmers’ views on elite varieties of pearl millet. Resistances to downy mildew, head miner, stem borer and rainstorms, drought; high grain yield, food quality, and earliness were the main preferred traits by farmers. Hybrid breeding is the most cost effective way to expand the production of this cereal while selecting for qualitative traits. Heterosis in millet is a function of both general and specific combining abilities. Hence, a study on heterosis and combinability was carried out using sixteen hybrids developed from eight locally adapted varieties belonging to two heterotic groups. The hybrids and their parents were tested in two locations, during 2010 and 2011, in a randomized complete block design. Data on yield and productivity related traits were recorded. Eight hybrids, which outyielded the check variety, have been identified. Among the parental varieties, HKB had the best GCA for grain yield and other traits. The hybrid between Gamoji and HKB had the highest SCA and the best yield. There was a good association between GCA, SCA and higher yield in pearl millet. Increased yield was found to be positively correlated with peduncle girth, tillering ability, spike length and other agronomic traits, while it was negatively correlated with the number of days to flower. Hybrids showed more phenotypic uniformity than their parents. GCAs for most traits were influenced by the environment. To guarantee a sustainable production stable yield against underlining the. Downy mildew is the most important disease on pearl millet and can threaten the stability of production throughout the whole country. The most plausible and cost effective way to control the disease with less risk, is to screen gerplasm. The parental genetic materials used in this study were inoculated with a mixture of Sclerospora graminicola in the field during two off seasons in 2011 and 2012 at Kollo. Parents and hybrids and seven checks were also inoculated with four isolates of S. graminicola under glass house conditions at ICRISAT-Sadoré in Niger. One hybrid, Ankoutess x Souna 3, was highly resistant to three of the four isolates. Four other combinations were highly resistant each to two isolates. The inheritance of resistance to downy mildew appeared to be controlled by a single dominant gene. An efficient hybrid breeding program also necessities a sound method for large scale seed production. This is made possible by the discovery of CMS by Burton in 1958. Development of male sterile A-line is necessary. To do this, ICMA 05 888 was selected to convert the local varieties into male sterile lines, while ICMR 06 111 was used to develop new restorer lines. To develop CMS lines, the local varieties were back crossed onto the CMS source to produce male sterile A-line and fertile, maintainer B-line. Seven of the eight varieties were able to be sterilized. Restorer versions of all eight local varieties were also obtained.