Improving pearl millet for drought tolerance - Retrospect and prospects

Drought stress is the most important production constraint of pearl millet (Pennisetum glaucum) in sub-Sahara Africa and south Asia where it is the staple diet and cheaper source of nutritious food for more than 90 million people. A much greater necessity therefore exists for improving pearl millet for drought-prone areas to attain food security in resource limited and fragile ecosystems. An attempt is made here to review the progress made in understanding the adaptation mechanism of pearl millet to drought situation and then to appraise how this knowledge has been used in improving drought-tolerance of pearl millet. A good amount of work has been accomplished in understanding the response of pearl millet to drought imposed at different growth stages of crop in order to understand its adaptation to drought stress. The foremost issues that have been addressed in breeding for enhanced drought tolerance in pearl millet are nature of base germplasm used, selection criterion, and representation of target environment during development, testing and evaluation of cultivars. Recent advancement in development and application of genomic tools in pearl millet is expected to improve the efficiency of breeding for improved drought tolerance. The major achievements in developing pearl millet specifically for drought conditions include identifying genetic material with built-in tolerance, developing early maturing cultivars, assigning importance to both grain and stover yields while releasing the cultivars, and identification of quantitative trait loci associated with drought tolerance. Prospects of further improvement of pearl millet for drought-prone areas are also discussed in this review.