Plant absorption of nitrogen (N) present in soil or supplied through fertilization is regulated by a complex of enzymes that act in a jointly and ordered way in the plant. The purpose of this research was to investigate the effects of the herbicides atrazine and ammonium glufosinate in N absorption by plants and their effects on corn plant traits. In one of the experiments (experiment 1), three atrazine rates were tested (0, 200, and 2000 g a.i. ha-1), three ammonium glufosinate rates (0, 40, and 80 g a.i. ha-1), and two N rates (0 and 90 kg ha-1). In another experiment (experiment 2), three herbicide treatments were tested (atrazine, 200 g a.i. ha-1; ammonium glufosinate, 40 g a.i. ha-1; atrazine + glufosinate, 200 + 40 g a.i. ha-1; and a check), two N sources (urea and ammonium nitrate), and two N rates (0 and 100 kg ha-1). Effects of the treatments were evaluated at 10 and 20 days after herbicide application (DAA) in experiment 1, and when corn plants presented 10 developed leaves (15 DAA) and at tasseling (40 DAA) in experiment 2. Statistical analyses revealed that N side dressing application in corn promotes an increase in most of the grain yield components and increases grain yield by 35%, and that such effects occur regardless of the N source used, urea or ammonium nitrate. There was no interaction effect among factors related to herbicides that are inhibitors of photosystem II (atrazine) and to herbicides inhibitors of the glutamine synthesis (ammonium glufosinate) and N side-dressing application in corn. The use of these herbicides in reduced rates, applied alone or in combination, did not affect grain yield nor yield components. Atrazine shows little consistency in affecting chlorophyll and N contents in corn; nevertheless, in some cases, its action is favorable, especially when used at the recommended rate or even when sprayed alone. Ammonium glufosinate, applied at reduced rates, in general does not affect N content in corn; however, in some situations, chlorophyll content is affected and, when used at 80 g a.i. ha-1, promotes N content increase in the corn tissue.
[1]
C. M. Mundstock,et al.
Regulação da absorção e assimilação do nitrogênio nas plantas
,
2000
.
[2]
Prikhshayat Singh,et al.
Effect of 2,4-D on the Nitrate Assimilation Process in Cowpea Shoot☆
,
1998
.
[3]
G. Coruzzi,et al.
THE MOLECULAR-GENETICS OF NITROGEN ASSIMILATION INTO AMINO ACIDS IN HIGHER PLANTS.
,
1996,
Annual review of plant physiology and plant molecular biology.
[4]
G. Coruzzi,et al.
Use of Arabidopsis mutants and genes to study amide amino acid biosynthesis.
,
1995,
The Plant cell.
[5]
L. Kleczkowski.
Inhibitors of Photosynthetic Enzymes/Carriers and Metabolism
,
1994
.
[6]
D. Turpin,et al.
Integration of Carbon and Nitrogen Metabolism in Plant and Algal Cells
,
1994
.
[7]
L. Klepper,et al.
Effects of ametryn [2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-s-triazine] on nitrate reductase activity and nitrite content of wheat (Triticum aestivum L.)
,
1979
.
[8]
L. Klepper.
Effects of certain herbicides and their combinations on nitrate and nitrite reduction.
,
1979,
Plant physiology.
[9]
D. Nicholas,et al.
Effects of atrazine on the assimilation of inorganic nitrogen in cereals
,
1978
.
[10]
C. Fedtke.
Formation of nitrite in plants treated with herbicides that inhibit photosynthesis
,
1977
.
[11]
L. Klepper.
Nitrite Accumulation Within Herbicide-Treated Leaves
,
1976,
Weed Science.
[12]
L. Klepper.
Inhibition of Nitrite Reduction with Photosynthetic Inhibitors
,
1975,
Weed Science.