Seletividade de herbicidas inibidores da protox e da biossíntese de carotenóides em clones do gênero eucalyptus

Abstract

The weeds in eucalypt stands may cause interference, and the use of herbicides becomes an essential tool. However selectivity can vary from the dose, cultivars, time and application technology. In this study, two experiments were conducted in a greenhouse at the Federal University of Alagoas. The study aimed to verify the influence of spray tips selectivity of herbicides, as well as the selectivity of different herbicides on seedlings of different clones crossing Eucalyptus Eucalyptus urophylla x Eucalyptus grandis. The first experiment aimed to evaluate the influence of spray tips, selectivity in VC865 clone seedlings. XR 110.02 and 110.02 TTI spray tips were used for herbicide application: control (0 g a.i. ha-1), oxyfluorfen (150 g a.i. ha-1) and saflufenacil (98 g a.i. ha-1). The experimental design was a factorial 2x3 (2 spray nozzles x 3 herbicide treatments), using a randomized block design with four replications. The second experiment was to evaluate the selectivity of herbicides on seedlings of eucalyptus clones was performed with a randomized block design in a factorial 6x3, where the factors were herbicides (6): control (0 g a.i. ha-1), isoxaflutole (150 g a.i. ha-1), flumioxazin (90 g a.i. ha-1), clomazone (900 g a.i. ha-1), oxyfluorfen (960 g a.i. ha-1) and saflufenacil (98 g a.i. ha-1), and Clones (3): VC865, CO1407 and I-144, with 5 repetitions. The application in both experiments was carried out 15 days after transplanting the seedlings. We evaluated the plant height (PH), stem diameter (DC), number of leaves (NF), total dry matter (DM), leaf area (AF), visual phytotoxicity (F), quantum efficiency of photosystem II - Fv / Fm (EQ), effective quantum yield of PSII - YIELD (Yii), the electron transport rate (ETR) and the Spad index (S). Spray tips XR 110.02 and 110.02 TTI, they showed little difference between them. The saflufenacil herbicides, clomazone and oxyfluorfen and flumioxazin despite having the highest phytotoxicity notes specifically in this order, did not cause reduction in biometric variables and physiological aspects of eucalyptus clones VC865, CO1407 and I-144, which showed recovery at 30 DAA and total absence of phytotoxicity after 35 DAA. The herbicide isoxaflutole not promoted as prominent changes in the studied parameters, compared to the control, which is the most suitable for use in plantations with eucalyptus seedlings.