NITROGEN IN FERTIGATION TO PRODUCE SEED OF PARENTAL LINES AND SINGLE CROSSES OF MAIZE: DOSE AND DISTRIBUTION

Abstract

The cost and the environmental impact of applying nitrogen fertilizer to produce hybrid maize (Zea mays L.) seed are high and opposed to sustainable development. The dose, distribution and form of applications are limited; thus, the application of N in fertigation and its effect on seed yield in parental lines and single crosses of maize hybrid were evaluated. In 2013 and 2014 lines M-54, M-55 and CML-242, single crosses M-54×M-55 and M-55×M-54, and the hybrid H-70 were evaluated with the doses of N 150, 225 and 300 kg ha^-1 in a randomized complete block design. The distribution of doses 150, 225 and 300N-60P-30K was carried through the biological cycle. Differences between genotypes, doses of N and years were statistically significant (P ≤ 0.01) for initiation of male (IMF) and female (IFF) flowering and seed yield. There was a difference of 7 to 11 days between M-54 and M-55 for IMF and IFF, and from 3 to 5 d between M-54×M-55 and CML-242. Lines and single crosses yielded an average of 3.28 and 8.44 Mg ha^-1, respectively. Doses of 225 and 300 kg N ha^-1 in fertigation delayed IMF and IFF by 1 to 3 d on average, compared to 150 kg N ha^-1, which had an average yield of 6.37 Mg ha^-1. In 2013 IMF and IFF increased by 4 and 2 d while the yield decreased by 3% compared to 2014. Line M-55 with a dose of 225 kg N ha^-1 in 2013 yielded 25 % more than with 150 kg N ha^-1. Applying 150 kg N ha^-1 in fertigation increases seed production and the doses of 225 and 300 kg N ha^-1 delay flowering.