Seedling Root and Coleoptile Length as Selection Criteria for Field Emergence in Pearl Millet

Abstract

ABSTRACT Pearl millet (Pennisetum glaucum [L.] R. Br.) production in semi-arid regions is limited by poor seedling emergence that results in poor stand establishment and, low yield. Six pearl millet populations were created by divergent selection within the Tift #2 S-1 (TIFT2) pearl millet population for seedling root length in sand in the greenhouse or seedling root or coleoptile length in paper germination towels in the laboratory. The TIFT2 population (TIFT2) and the six selected populations were grown in the field in a randomized complete block design at Mississippi State, MS (MSU) and at Katumani and Kiboko, Kenya in 1991 and 1992. Populations were evaluated for seedling emergence and shoot height every 3 d for the first 15 d after planting. The greatest differences in emergence occurred at the most water-stressed locations in both years. The population selected for longer seedling root length in sand (LR-S) generally showed the highest field seedling emergence and shoot height during the first 9 d. Emergence of the LR-S population (18.8, 11.3, and 9.8 seedlings) at 15 d was significantly greater than TIFT2 (11.3, 5.7, and 4.3 seedlings) in the more moisture-stressed locations, Katumani and MSU in 1991 and Kiboko in 1992, respectively. Emergence of the LR-S population exceeded that of TIFT2 in every case except day 6 at MSU in 1992. The LR-S population also exhibited the fastest rates of emergence (1.1 to 2.1 seedlings d−1) at the most water-stressed locations. The LR-S population was able to tolerate or avoid moisture stress better than the other populations. There was little or no increase in seedling emergence or shoot height with selection for coleoptile length or seedling root length in paper germination towels. Selection for seedling root length in sand culture in the greenhouse demonstrated promise as an indirect selection criterion for increased seedling emergence and shoot height.