Herbicide tolerance and water use efficiency in forest species used in degraded areas recovery programs

Abstract

The use of tree species in recovery areas is a sustainable practice in many Brazilian regions. However, a major challenge is to manage invasive species and contain the herbicide residues applied in areas for recovery. Amid all the concerns about water crises, employing species with a better use of water in recovery programs of degraded areas on herbicides-contaminated sites becomes interesting. The objective of this study was to evaluate sensitivity to atrazine, clomazone and 2,4-D and water use efficiency in tree species. For this, an experiment was conducted under nursery and greenhouse conditions, in random blocks, consisting of a factorial arrangement: eight forest species (Eremanthus crotonoides, Richeria grandis, Protium heptaphyllum, Tapirira guianensis, Kielmeyera latrophyton, Calophyllum brasiliense, Inga striata and Caesalpinia ferrea) and three herbicide solutions, plus the control group. The total dose proposed for each product was twice the average recommended dose (2.5 kg ha^-1, 2.0 L ha^-1 and 0.806 kg ha^-1, respectively, for atrazine, clomazone and 2,4-D), divided into six ten-day intervals each. After 80 days of the first application, phytotoxicity was evaluated, as well as chlorophyll, leaf temperature, leaf area and efficient use of water. Most species were negatively affected by the three herbicides. Protium heptaphyllum, K. latrophyton, I. striata and C. ferrea also experienced negative alterations in some variables, however, they were classified as the less sensitive group, allowing eventual use of the tested herbicides for chemical weed control in commercial plantations. Tapirira guianensis was the most efficient species in the use of water, regardless of herbicide presence.