Effect of the nitrogen fertilization on the selectivity of post-emergenceherbicides for the culture of the corn

• Grant number: 09/15852-7
• Support type: Regular Research Grants
• Duration: September 01, 2010 - August 31, 2011
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal researcher: Fernando Tadeu de Carvalho
• Grantee: Fernando Tadeu de Carvalho
• Home Institution: Faculdade de Engenharia (FEIS). Universidade Estadual Paulista (UNESP). Campus de Ilha Solteira. Ilha Solteira , SP, Brazil

Abstract

The selectivity of the herbicides to the plantations can to have the interfered by external factors to the application. In the case of the culture of the corn, there is a concern of not apply the herbicide nicosulfuron in the time of the nitrogen fertilization because there is the risk of causing phytotoxicitys. However, this information does not contain scientific backrest, since there are no works proving the fact. The present work will be developed with the objective of analyzing the interaction between the nitrogen fertilization and also the moment of the application of post-emergence herbicides in the selectivity for the culture of the corn. The experiment will be installed using two corn cultivars with sowing in November /2010 in the FEP-FEIS-UNESP, located in the municipal district of Selvíria, MS. The experimental area will be prepared conventionally for the corn sowing (hybrid). The experimental design will be blocks at random with four replications in a factorial 2 x 4 x 8: being the factor 1 the corn cultivars, the factor 2 the herbicide type and the factor 3 the moment of herbicide application. Each portion will consist of 4 lines with 5 m of length and 4 m of width. The treatments will be applied in post-emergency of the culture using a costal pulverizer with constant pressure (CO2) of 45 lb.pol-2, with a bar equipped with beaks of the fan type and with volume of syrup of 200 L/ha. The selectivity evaluations will be accomplished weekly until the disappearance of the phytotoxicitys symptoms using a visual scale in offense percentage where 0% = any symptom and 100% = total death of the culture and through an apparel (portable fluorometer) that analyzes the punctual phytosanity of the culture after the application of the treatments. Analyses of growth of the culture will be accomplished evaluating plant height, the height of ear height and the diameter of the plants. At harvest will be counted the number of plants and the number of spike of the useful area and, after threshing, will be determined the moisture content of grain, the 100 grains weight corrected to 13% (wet basis), the number of grains per spike and the productivity estimated in kg.ha-1, based in 13% (wet basis). (AU)