B. S. Colares

The research proposal was part of the evaluation of the application technology, control efficiency and selectivity of the chia crop (Salvia hispanica L.) subjected to sequential applications of herbicides inhibiting the enzyme ACCase. The experiment was conducted under field and in the laboratory conditions at the State University of the Midwestern Paraná State University (UNICENTRO), CEDETEG Campus, Guarapuava, Paraná, Brazil. The treatments consisted of the sequential application of clethodim (108 and 216 g ha-1), sethoxydim (184 and 368 g ha-1), tepraloxydim (200, 100 and 200 g ha-1), haloxyfop (48 and 96 g ha-1), fenoxaprop (110 and 220 g ha-1), quizalofop (120 and 240 g ha-1), fluazifop (250 and 500 g ha-1), weeded control and unweeded control. All herbicides were associated with the adjuvant mineral oil Assist™ (0.25 L ha-1) and sprayed with an application rate of 200 L ha-1. No significant differences were found between the treatments for the spray deposition of herbicides applied to crabgrass (Digitaria horizontalis). In chia, the average deposition of the treatments clethodim (216 g ha-1), sethoxydim (368 g ha-1), tepraloxydim, haloxyfop and fenoxaprop was 16.5% higher than the group of other herbicides. All herbicides were efficient for crabgrass, especially in sequential application, although they caused height reduction and more evident phytotoxicity symptoms in the crop in the second application (≤18%). However, only haloxyfop (48 and 96 g ha-1) and quizalofop (240 g ha-1) were not considered selective for sequential application in chia because they reduced grain yield by around 15.3% and 26.7%, respectively.

Soybean has significant importance in the global agricultural sector. However, yield is often compromised by the low availability of phosphorus in the soil. The inoculation of phosphate-solubilizing bacteria has shown promise in increasing the absorption of this nutrient. Therefore, this study aimed to evaluate the efficiency of Bacillus licheniformis as a phosphorus solubilizer, as well as to investigate its impact on soybean crop development. The experimental design was a randomized block design arranged in a 4x2 factorial scheme, with four replications. Treatments consisted of four phosphate fertilization rates (0, 40, 60, and 80 kg ha−1 P2O5, applied as single superphosphate and equivalent to 0, 50%, 75%, and 100% the recommended rate) associated or not with inoculation with Bacillus licheniformis. Morphological variables (plant height, root length, stem diameter, and branch number) and yield components (pods per plant, seeds per plant, seeds per pod, thousand grain weight, and grain yield) were determined. There were no significant effects of biological inoculation or phosphorus rate on morphological characteristics or some yield components, attributed to the high content of available phosphorus in the experimental soil (39.3 mg dm−3). On the other hand, inoculation with B. licheniformis significantly increased thousand grain weight and grain yield, even under high phosphorus availability. Regression analysis indicated that both variables had a positive linear response to phosphorus rate. These results reinforce the agronomic potential of B. licheniformis as a complementary technology to phosphate fertilization, contributing to the sustainability of soybean production.

This study aimed to evaluate the efficacy of the herbicide pyraflufen-ethyl, with and without the adjuvant, for the control of Raphanus raphanistrum (wild radish) in wheat pre-sowing, as well as the spray deposition dynamics and physicochemical properties of the spray solutions. Two experiments were conducted under field and laboratory conditions, comprising 12 treatments: pyraflufen-ethyl (7.5, 8.75, 10.0, 11.25, and 12.5 g ha-1), applied with and without the adjuvant (Lanzar® 0.2% v/v), iodosulfuron-methyl (10.0 g ha-1), and an untreated control, in a completely randomized design. Results indicated that the tank mixture of pyraflufen-ethyl with the adjuvant reduced pH, increased electrical conductivity, and had little effect on the static surface tension of the solutions. The combination of pyraflufen-ethyl with the adjuvant Lanzar® (0.2% v/v) decreases pH, increases electrical conductivity, and has minimal effect on the surface tension of the solutions. Pyraflufen-ethyl, from a dose of 7.5 g ha−1 combined with the adjuvant Lanzar® (0.2% v/v), significantly enhanced spray deposition and the speed of control of Raphanus raphanistrum, while also demonstrating selectivity for use in pre-sowing applications in wheat cultivation.

Potassium fertilization is essential for cassava cultivation, especially in sandy soils with low nutrient availability. This study aimed to evaluate the growth, development, and yield of cassava in response to increasing rates of potassium chloride (60% K2O), as well as to assess the feasibility of applying higher rates. The experiment was carried out in a randomized block design with four replications and five treatments: T1 – no potassium fertilization; T2 – 200 kg ha−1 of KCl applied 45 days after planting; T3 – 200 kg ha−1 of KCl at 45 days plus 200 kg ha−1 at 90 days after planting; T4 – 267 kg ha−1 of KCl at 45 days; and T5 – 267 kg ha−1 of KCl at 45 days plus 267 kg ha−1 at 90 days after planting. Five plants were harvested per plot to determine the number and mass (kg) of tuberous roots, allowing estimation of the total number of roots per hectare and yield (kg ha−1). From each harvested plant, one root was randomly selected for measuring length (cm) and diameter (cm). Starch content (g kg−1) was determined using the hydrostatic balance method. No significant differences among treatments were observed for root length, diameter, or starch content. However, treatments with 200 kg ha−1 of KCl (T2 and T3) showed higher root numbers per hectare and yield compared with the others. The management with doubled potassium rates was not economically feasible, since the productivity gain did not offset the increased fertilizer cost.