Pf. Byrne et al., GAINS FROM SELECTION UNDER DROUGHT VERSUS MULTILOCATION TESTING IN RELATED TROPICAL MAIZE POPULATIONS, Crop science, 35(1), 1995, pp. 63-69
Ideal maize (Zea mays L.) cultivars for tropical areas should yield we
ll both in the presence and absence of drought, but optimal selection
strategies for accomplishing this goal are not clear. This study evalu
ated progress from selection of two related tropical populations acros
s a broad range of environmental conditions. 'Tuxpeno Sequia' (TS) had
undergone full-sib recurrent selection for eight cycles at one locati
on under managed levels of drought stress, while Tuxpeno 1' (T1) was s
elected for six cycles in a modified full-sib selection scheme that re
lied heavily on multilocation yield trial data. Combined over 12 envir
onments (with mean yields ranging from 0.30-7.83 Mg ha(-1)), regressio
n analysis revealed significantly different rates of change per cycle
for TS and T1, respectively, for grain yield (1.68 and 1.06%, P < 0.10
), anthesis-silking interval (ASI) (-8.59 and 0%, P < 0.10), ears per
plant (1.26 and 0%, P < 0.05), and plant height (-0.83 and 1.29%, P <
0.01). Days to anthesis decreased in both TS and T1 (-0.36 and -0.15%
per cycle, respectively), but the difference between populations was n
ot significant at P < 0.10. The interaction of environments with the l
inear rate of gain in grain yield was not significant in either popula
tion, indicating similar progress across the range of environmental co
nditions sampled. Stability analysis indicated that TS Cycles 6 and 8
and the check variety 'La Posta Sequia Best' were the most stable and
high yielding entries in the trial. Better yield gain in TS is likely
related to its selection for reduced ASI under controlled stress at a
single site. Selection under managed levels of drought stress at one l
ocation together with multilocation testing may be desirable component
s of maize breeding programs for drought-prone tropical areas.