Interference Periods of Weeds Infesting Maize Crop

Luciane Renata Agazzi,Leandro Galon,César Tiago Forte,Felipe Nonemacher,Lauri Lourenço Radunz,Francisco Wilson Reichert Júnior,Maico André Michelon Bagnara,Felipe José Menin Basso,Ricardo Luis Gabiatti

doi:10.5539/jas.v10n10p197

Abstract

When competing with crops, weeds interfere with their growth and consequently reduce grain yield. The purpose of this research was to determine the periods of interference; PIP (pre-interference period), TPWC (total period of weed control), and CPWC (critical period of weed control) of the weeds Alexandergrass (Urochloa plantaginea) and southern crabgrass (Digitaria ciliares) in maize. The experiment was conducted in a randomized complete block design with four replications, in a no-tillage system. The treatments consisted in maintaining maize in the presence and absence of Alexandergrass and southern crabgrass for increasing periods of 0, 7, 14, 21, 28, 35 and 42 days after emergence (DAE). Southern crabgrass and Alexandergrass weeds originated from the soil seed bank with an average density of 215 and 87 plants m-2, respectively. At the end of each period, PIP or TPWC, the weed and crop dry biomass was determined. At 42 DAE, the height and stem diameter of maize plants were evaluated. At harvest 10 maize plants per experimental unit were evaluated for length of ears, number of rows per ear, and number of grains per row. Yield was measured by taking three central rows from each experimental unit. The results indicate that the PIP was 17 DAE, the TPWC was 32 DAE, and the CPWC was 17 to 32 DAE.

Highlights

Maize (Zea mays L.) is one of the most important crops in the world, used for both human and animal consumption or even for energy production
A reduction in stem diameter and maize height was observed as the maize coexisted longer with weeds, that is, from 0 to 42 days after emergence (DAE)
For the weed control model treatments, there were no differences, except for the stem diameter at 0 DAE, which was lower than the other weed control periods

Summary

Introduction

Maize (Zea mays L.) is one of the most important crops in the world, used for both human and animal consumption or even for energy production. In Brazil, maize is one of the most economically and socially important crops, with an estimate of 4.97 million hectares in production, yielding 5.05 t ha-1, and producing 92.34 million tons in the 2017/18 crop year (CONAB, 2017). Maize productivity is lower than that obtained in areas that adopt high technological levels or experimental areas, because it is affected by several factors. It is estimated that yield losses in maize as a function of competition with weeds are in the order of 13% (Carvalho et al, 2007). In many situations, where no control measures are adopted, this reduction can reach 85% (Carvalho et al, 2007) or more than 90% (Merotto Jr. et al, 1997; Galon et al, 2008)

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