Farmers' seed systems and management practices determine pearl millet genetic diversity patterns in semiarid regions of India

Pearl millet [Pennisetum glaucum (L.) R. Br.] landraces provide nutritional quality and security under the harsh environmental conditions of Rajasthan, India. Using amplified fragment length polymorphism (AFLP), this study investigated pearl millet genetic diversity patterns and related the results to farmers' local knowledge and seed systems. Thirty-nine cultivars were assessed: 14 farmer landraces from western Rajasthan, 13 farmer landraces from eastern Rajasthan, and 112 control cultivars. Shannons' information index for western (H = 0.34) and eastern (H = 0.32) Rajasthan landraces was up to 14% higher than in composite-based improved cultivars. Analysis of molecular variance (AMOVA) revealed that variation within landrace populations was much higher than between regional samples. In the west, intra-village variation was higher than inter-village variation. In the east, variation between landrace groups bearing a specific name was higher than intra-group variation. Gene flow, inferred from genetic distances between populations, was used as an indicator for seed exchange between farmers. In western Rajasthan, seed exchange appears to be especially dynamic, as gene How was greater than N(e)m = 25 among most of its populations. Farmers' knowledge of local cultivars and seed systems was, for the most part, supported by the AFLP analysis. These results are relevant for in situ maintenance and breeding strategies with a view to improving traditional cultivars, specifically performance and yielding stability.