EFFECT OF WATER AND NITROGEN STRESS ON ROOTS OF HYBRID AND CREOLE VARIETIES OF MAIZE (Zea mays L.)

Abstract

With the objective of evaluating the response from a group of hybrid and Creole varieties of maize (Zea mays L.), in terms of accumulation of dry material from roots, under conditions of irrigation, drought and nitrogen deficiency in greenhouse, two old hybrids (H-28 and H-30), two modern (H-48 and H-50), and two Creole (white and blue grain) maize varieties were evaluated. A completely random block design with two repetitions in a 4X2 factorial arrangement was used, and the experimental unit was of one tube (PVC, 1 mx4”), filled with sandy loam soil (CC=33.9% and PMP=21.1%). The maize variants were subject to irrigation during their biological cycle; S₁, 10 days without irrigation (30-40 dds); S₂, 20 days without irrigation (50-70 dds), and S₃, 30 days without irrigation (70-100 dds) with high nitrogen (AN, 160-40-20) and low nitrogen (BN, 80-4020) applied in the sowing. The decrease of soil hydric content was reflected in a higher (p?0.05) accumulation of dry matter in the roots of plants subject to drought. The plants under drought produced a higher dry weight of roots than those under irrigation. These differences between soil moisture were higher than those observed between levels of nitrogen. The average accumulation of dry matter from roots was higher (p?0.05) in improved varieties than in Creole ones under conditions of drought and nitrogen deficiency.