Reação a doenças em variedades de algodoeiro resistentes a herbicidas

Abstract

The purpose of this work was to compare the reaction to ramulosis and Fusarium wilt of two genotypes of cotton, on the conventional form, transgenic and transgenic with the herbicide use, in controlled terms, and the reaction to diseases of a transgenic varieties and a conventional in different culture systems. In controlled terms (greenhouse) index diseases were evaluated, the altitude and the plant dry mass of two genotypes of cotton on the ways: conventional (FiberMax 966 and DeltaOpal); transgenic (FiberMax 966 LL and NuOpal) and transgenic with the herbicide use (FiberMax 966 LL + Ammonium Glufosinate and NuOpal + Glyphosate), inoculated with the diseases ramulosis and Fusarium wilt. In field, the mass of a thousand seeds, productivity and the severity of ramularia and myrothecium leaf spot of two conventional species (FiberMax 910) and transgenic (FiberMax 966 LL) in four culture systems. The reaction genotypes of cotton plant in the different ways vary according to the disease. In the presence of ramulosis, both the diseases, the transgenic form presents the largest index. In the presence of Fusarium wilt, around 60 days after the inoculation, the conventional form (FiberMax 966) and the transgenic with herbicide application (NuOpal + Glyphosate) presents the largest index of disease. The reactions of a conventional variety and of a transgenic differ according to the culture system adopted. In the acres localized in the cities of Primavera do Leste and Pedra Preta, where it was adopted the plantation with conventional spacing (90 cm), occurs reaction similar between the varieties relative to the severity of ramularia disease. The acre with spacing super dense (45 cm) presents severe reaction, for both diseases, ramularia and myrothecium leaf spot . The reaction to the ramularia disease is upper in the conventional variety in the culture system of dense plantation (76 cm), in plants with high altitude and with reduced use of fungicide.