The influence of 2,4-D and dicamba on the physiology of olive seedlings

Abstract

Abstract The objective of this work was to evaluate the influence of herbicides 2,4-D and dicamba on the physiological response of chlorophyll a in olive (Olea europaea) seedlings. The following eight rates of the 2,4 D (670 g a.e. ha-1) and dicamba (720 g a.e. ha-1) herbicides were applied: 0, 1.56, 3.13, 6.25, 12, 25, 50, and 100% of the recommended for burndown. The herbicides were applied at 80 cm above the seedlings using a CO2 pressurized back sprayer with a 150 L ha-1 spray volume. Plant gas exchange was measured using a portable infrared gas analyzer. Chlorophyll a fluorescence was evaluated using a portable modulated light fluorometer. The application of both herbicides caused a decrease in the process of CO2 assimilation in the plants, reducing net photosynthesis and stomatal conductance. The 2,4-D herbicide caused the most severe effects on the variables related to chlorophyll a fluorescence. Low values of maximum quantic yield were observed after the application of the herbicides, of which dicamba was the most harmful. Both herbicides damage the photosynthetic apparatus of olive seedlings.

Keywords

• Olea europaea
• conductance
• herbicide
• net photosynthesis