Gains from improvement for mid-season drought tolerance in tropical maize (Zea mays L.) uri icon

abstract

  • Drought and low soil fertility are major factors limiting maize production in the tropics. We examined the performance of hybrid progenies of drought-tolerant populations (DTP) in stressed (drought and low-N) and unstressed environments. A set of high-yielding normal single cross hybrids, developed using inbred lines improved with main emphasis on yield per se under optimal input conditions, was evaluated and compared with DTP c9 S-3 topcrosses across environments. Performance of normal hybrids was slightly better than DTP-topcrosses under unstressed conditions. However, under stress normal hybrids performed poorly with an average yield of 3.3-4.8% under drought and 34.8-36.2% under low-N stress. Hybrid progenies from DTP yielded up to 31.8-42.4% under drought and 48.9-63.6% under low-N as compared with their yields with out stress. Estimation of gains with selection for mid-season drought stress in DTPs over selection for improved yields under optimal input conditions showed that the gains were remarkable for drought (89.6%), and also for low-N stress (39.3%). The improved performance of DTP hybrids across environments was due to improvements in secondary traits such as reduced anthesis-silking interval, increased ears per plant, delayed senescence and relatively high leaf chlorophyll during late grain filling. Correlations between the performance of genotypes under drought and low-N stresses were positive and fairly high for DTP progenies, both white (r(2) = 0.45(*): r = 0.56(*)) and yellow (r(2) = 0.42(*), r = 0.52(*)), while it was not significant with normal hybrids. Selection for mid-season drought tolerance resulted in morpho-physiological changes that proved advantageous under both drought and low-N stress, without significant yield penalties under optimal input conditions. (C) 2004 Elsevier B.V. All rights reserved.

publication date

  • 2004
  • 2004
  • 2004