Foliar levels of macro and micronutrients in glyphosate-tolerant corn submitted to herbicides

Abstract

A serial of factors related to development of glyphosate-tolerant corn should be approached and best studied. This work was developed to evaluate foliar levels of N, P, K, Ca, Mg, S, B, Cu, Fe, Mn and Zn, besides the grain yield of glyphosate-tolerant corn (DKB390 RR hybrid). An experiment was carried out under field conditions, during the crop year of 2010/2011. A randomized complete block design with four repetitions was used to distribute the treatments in the field. Twelve herbicide treatments were studied: glyphosate (720, 1200 and sequential application of 960 plus 720 g ha-1 of the acid glyphosate equivalent), atrazine (2500 g ha-1), nicosulfuron (60 g ha-1), mesotrione (192 g ha-1), tembotrione (100,8 g ha-1), atrazine plus glyphosate (1000 + 960 g ha-1), atrazine plus nicosulfuron (1000 + 20 g ha-1), atrazine plus mesotrione (1000 + 144 g ha-1) and atrazine plus tembotrione (1000 + 75,6 g ha-1) and one control treatment without herbicide. The glyphosate and mesotrione alone did not cause no visible injury to corn. The other herbicides caused intoxication symptoms classified as light (<5%). The treatments studied did not affect foliar levels of N, P, K, Ca, Mg, S, B, Mn and Zn in the corn plants. But, the plants treated with atrazine plus nicosulfuron had more leaf Fe content, and the plants sprayed with glyphosate (in the three doses) and atrazine, more accumulation of Cu in the leaf. The Grain yield of corn was reduced with application single of glyphosate (1200 g ha-1), nicosulfuron, tembotrione and with the mixture atrazine plus nicosulfuron.