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This article in CS

  1. Vol. 39 No. 5, p. 1306-1315
    Received: Aug 27, 1998

    * Corresponding author(s): edmeadgreg@hibred.com
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Selection Improves Drought Tolerance in Tropical Maize Populations: I. Gains in Biomass, Grain Yield, and Harvest Index

  1. G.O. Edmeades *a,
  2. J. Bola n ˜ osb,
  3. S.C. Chapmanc,
  4. H.R. Lafitted and
  5. M. B a ¨ nzigerb
  1. a Pioneer Hi-Bred International, Inc., 7431 Kaumualii Highway, P.O. Box 596, Kekaha, HI 96752 USA
    b CIMMYT, Apdo. Postal 6-641, 06600 Mexico D.F., Mexico
    c CSIRO Tropical Agriculture, 306 Carmody Rd., St. Lucia, QLD 4067, Australia
    d IRRI, P.O. Box 933, Manila, Philippines


Drought is common in tropical environments, and selection for drought tolerance is one way of reducing the impacts of water deficit on crop yield. The primary objective of this study was to evaluate biomass, grain yield, and harvest index of maize (Zea mays L.) populations selected for drought tolerance. Three late-maturing tropical maize populations were subjected to three cycles of S 1 recurrent selection (`La Posta Sequı́a' and `Pool 26 Sequı́a') or eight cycles of full-sib recurrent selection (`Tuxpeño Sequı́a') for yield and traits indicative of drought tolerance during flowering and grain filling. Selection gains were assessed in five trials conducted under mid–late season drought and in five trials conducted under well-watered conditions. In water-stressed environments, with average yields of 1.0 to 4.5 Mg ha−1, yield gains averaged 0.26 Mg ha−1 (12.6%) cycle−1 for La Posta Sequı́a and Pool 26 Sequı́a and 0.08 Mg ha−1 (3.8%) cycle−1 for Tuxpeño Sequı́a. In well-watered conditions, where mean yields ranged from 5.8 to 10.4 Mg ha−1, corresponding gains per cycle were 0.12 Mg ha−1 (1.5%) and 0.04 Mg ha−1 (0.5%). Total biomass was unaffected by selection. Mean correlated responses to selection observed under drought were −0.11 Mg ha−1 cycle−1 in stem biomass and 0.025 cycle−1 in harvest index (HI), and under well-watered conditions, 0.005 cycle−1 in HI. Stem biomass and HI were negatively correlated under drought ( r = −0.57; P < 0.01) Improved drought tolerance was attributed to simultaneous selection in well-watered environments and under carefully managed water stress at flowering, resulting in greater partitioning of biomass to the ear and increased harvest index.

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Copyright © 1999. Crop Science Society of AmericaCrop Science Society of America