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Herbicide promotes physiological and biochemical changes even in tolerant species. The objective of this study was to evaluate the interference of the herbicides clodinafop-propargyl and 2,4-D in the antioxidant system of wheat, and iodosulfuron-methyl in wheat and ryegrass. Two studies, divided into three experiments, were conducted in an entirely randomized design in a greenhouse and phytotron. The first study tested herbicides iodosulfuron-methyl, clodinafop-propargyl, 2,4-D, and a control without application in wheat. The second, divided into two experiments with wheat and ryegrass, tested iodosulfuron-methyl doses (0, 1.75, 3.5, and 7.0 g a.i. ha-1). The variables analyzed were the concentrations of chlorophylls a, b, carotenoids, hydrogen peroxide (H2O2), lipid peroxidation (TBARS), electrolyte leakage, and antioxidant system activity. The herbicide treatments iodosulfuron-methyl, clodinafop-propargyl, and 2,4-D decreased the concentrations of chlorophylls and carotenoids in wheat plants. The herbicides promoted oxidative stress with increased H2O2 and TBARS concentrations. Increasing the dose of iodosulfuron-methyl provided a reduction in the activity of the enzymatic antioxidant system in wheat and ryegrass. [ABSTRACT FROM AUTHOR]

The application of plant growth regulators represents an alternative to attenuate the occurrence of stress in crops, such as periods of water scarcity in canola (Brassica napus L.). Therefore, the objective was to evaluate the application of salicylic acid in the initial development of the crop. of canola subjected to water deficit. The experiment was carried out in a greenhouse, in a randomized block design in a 5 x 2 factorial scheme, consisting of five doses of salicylic acid (0; 0.5; 1.0; 1.5 and 2.0 mM L-1 ) and two water regimes, with and without water deficit (25% and 80% of vessel capacity), with four replications. The variables analyzed were visual injuries, plant height, chlorophyll content and shoot dry mass. The application of different doses of salicylic acid did not present significant differences in relation to non-application. The water deficit resulted in a higher percentage of injuries, lower height and dry mass of plants, indicating the occurrence of stress to the crop. The application of salicylic acid did not attenuate the effects of water deficit, as well as it did not demonstrate beneficial effects on the development of canola plants. [ABSTRACT FROM AUTHOR]

Fast perishability of dragon fruit requires that strategies be adopted to extend its post-harvest shelf life, in order to reduce losses, maintain quality and increase the financial return of economic activity. The objective of this work was to evaluate the effect of storage conditions in combination with the application of 1-methylcyclopropene (1-MCP) on the quality maintenance of red dragon fruit. The treatments evaluated were cold storage (CS; 21 kPa O2 + 0.03 kPa CO2), controlled atmosphere (CA; 2 kPa O2 + 5 kPa CO2) and modified atmosphere (MA; 40 µm thick low-density polyethylene bags) combined or not with the application of 1-MCP (300 nL.L-1), with four replications per treatment. The fruits of all treatments were stored for 20 days at 13 ± 2°C and relative humidity (RH) of 90 ± 5%, followed by 3 days of exposure at ambient conditions (20 ± 3°C and RH of 70 ± 5%). After the shelf life, CA and MA maintained fruits with a higher hue angle. The treatment of 1-MPC added to CA and MA provided greater force for pulp penetration. CS, AC and MA, added to the treatment with 1-MCP, are promising technologies to be used in the storage of dragon fruit. [ABSTRACT FROM AUTHOR]