Selection for response to low nitrogen in the La Posta maize population - Mexico, DF (Mexico) CIMMYT : 1997 - Printed
Improved maize cultivars that require low levels of nitrogen fertilization to produce high grain yields would be highly desirable for areas practicing low input agriculture. We conducted two studies in a lowland tropical maize population to 1) estimate the effectiveness of recurrent selection for improved agronomic performance in the population under low levels of applied N, and 2) determine the effects of six cycles of recurrent selection on the N response of the population. In one study, 100 randomly chosen full-sib families from La Posta maize population were evaluated at 40 (low N) and 160 (high N) kg N ha-1 applied as ammonium sulfate at two locations in 1985 and 1986 in Ghana, West Africa. Expected genetic gain per cycle of full-sib selection for grain yield, mid-silk, plant height and grain moisture were 4.6, 2.4, 2.8, 8.4% at low N and 5.0, 1.9, 1.4, 5.4% at high N, respectively. In the other study, cycles 0, 2, 4, and 6 of La Posta were evaluated at 0, 80, and 160 kg N ha-1 at six locations in 1986. Between C0 and C6, yields increased by 0.26, 0.50 and 0.63 t ha-1 at 0, 80 and 160 kg ha-1 of N applied, respectively. It was concluded from the two studies that recurrent selection would be effective in improving the population under low and high N, although absolute gains are lower under low N.
633.153 / EDM