Sintomas de fitotoxicidade e crescimento de mudas de café submetidas aos herbicidas inibidores da protox

Abstract

This research aimed to evaluate the influence of the herbicides flumioxazin, oxyfluorfen and carfentrazoneethyl in initial growth of coffee seedlings under field conditions, identifying the phytotoxicity symptoms caused in plants. The experiments were performed in a randomized block design with four replicates and six doses of the herbicides (0%, 10%, 40%, 70%, 100% and 200% of the recommended dose). The herbicides were applied directly onto the plants using a knapsack sprayer pressurized by CO2 and regulated to 45 kgf/cm². After the pulverization, the seedlings remained in field for 45 days, being performed the identification and observation of the symptoms of phytotoxicity. The observation of the phytotoxicity symptoms was done each two days, by the capture of images and the comparison of plants that received herbicides against the pattern. At the end of the experiment were evaluated the number of leaves, stem diameter and plant dry weight. In the herbicides oxyfluorfen, carfentrazone-ethyl and flumioxazin, from the dose of 10%, the main symptom of phytotoxicity observed was the formation of irregular necrotic spots on the leaf surface, mainly in the apical regions. The oxyfluorfen and carfentrazone-ethyl herbicides, on all studied doses, despite causing phytotoxicity and light injuries in coffee seedlings did not affect its growing. The flumioxazin herbicide showed higher phytotoxicity in plants, significantly reducing their growing compared to control, starting at the 10% dose.