Ecological stability of genetic diversity among landraces of little millet (Panicum sumatrense) in south India

Risk-prone agriculture by resource-poor tribal farmers in Kolli hills, south India is slowly giving way to commercial exploitation for paltry compensation thus eroding genetic diversity of millets. Cultivation and conservation of millets, particularly, little millet (Panicum sumatrense Roth ex Roem. et Schult.), called samai in the local language, Tamil are on the wane. Whether irregular and sparse cultivation of little millet by tribals has an impact on the current level of genetic divergence is also not clear. Therefore genetic divergence among 7 landraces and 1 check variety was evaluated based on morphometric traits at two sites over two seasons. The seven landraces formed six distinct groups with high inter-group distances. Days to maturity and flowering time contributed the most to genetic differentiation. Principal component analysis confirmed the results of divergence analysis. But a recent molecular analysis of diversity reported that the landraces were all genetically uniform and any observed diversity could be due environmental variation. An analysis of the contradictory results only emphasized the fact that lack of polymorphism need not imply lack of genetic divergence. The findings co evaluated with relevant published work highlight the value of morphometric analysis and reveal sustained genetic divergence in little millet.