The use of magnetizers for the treatment of irrigation water can be used in agriculture as an alternative to increase the growth and yield of several crops. The objective of this study was to evaluate the effect of different irrigation depths and magnetic treatment of water on eggplant crop cultivated in protected environment. The study was carried out in two experiments, in the first one, the design was completely randomized with four replications and two factors: water depths (50, 75 and 100% ETc) for two water qualities (water treated by magnetizers and water without treatment). In the second one, the design was completely randomized with five replicates and two factors: water depths (75 and 100% ETc) for two irrigation water treatment (water treated by magnetizers and water without treatment). In the second experiment was ignored the treatment of 50% of ETc in order to increase the number of repetitions to check if there are differences between water treated to water without treatment. There were no significant differences in eggplant yield and growth as function of the magnetic treatment of water. The water depth that provided the highest yield, number of fruits per plant and stem dry matter in the two experiments was 100% ETc regardless of water quality.

Nanoformulations have been used to improve the delivery of fertilizers, pesticides, and growth regulators, with a focus on more sustainable agriculture. Nanoherbicide research has focused on efficiency gains through targeted delivery and environmental risk reduction. However, research on the behavior and safety of the application of these formulations in cropping systems is still limited. Organic matter contained in cropping systems can change the dynamics of herbicide–soil interactions in the presence of nanoformulations. The aim of this study was to use classical protocols from regulatory studies to understand the retention and mobility dynamics of a metribuzin nanoformulation, compared to a conventional formulation. We used different soil systems and soil with added fresh organic material. The batch method was used for sorption–desorption studies and soil thin layer chromatography for mobility studies, both by radiometric techniques. Sorption parameters for both formulations showed that retention is a reversible process in all soil systems (H~1.0). In deep soil with added fresh organic material, nanoformulation was more sorbed (14.61 ± 1.41%) than commercial formulation (9.72 ± 1.81%) (p < 0.05). However, even with the presence of straw as a physical barrier, metribuzin in nano and conventional formulations was mobile in the soil, indicating that the straw can act as a barrier to reduce herbicide mobility but is not impeditive to herbicide availability in the soil. Our results suggest that environmental safety depends on organic material maintenance in the soil system. The availability can be essential for weed control, associated with nanoformulation efficiency, in relation to the conventional formulation.

Pre-emergent herbicides are applied directly in the soil or over the straw in no-till systems and can be retained, reducing the product’s availability. The current study characterizes the retention of diclosulam and diuron in forage turnip (FT), buckwheat (BW), and black oat (BO) straws. Radiometric techniques evaluated the sorption–desorption and leaching processes. Spectroscopic and microscopic methods characterized chemical and morphological alterations in the straw. Sorption rates (Kf) of diclosulam and diuron followed the order BO > BW > FT. Irreversible sorption (hysteresis < 0.7) occurs to diclosulam applied to BO straw. The BO straw showed porous structures, indicating physical entrapment of the herbicides. Straw fragments (<1 mm) increased the sorption of herbicides. The increase in straw amount (2.5 to 5 t ha−1) reduced herbicide leaching to 18.8%. Interactions between chemical groups (C-Cl, C-F, and C-N) from herbicides with straw characterize a chemical barrier. The present research suggests that entrapment and chemical interaction are involved in the sorption–desorption process of herbicides, such as diclosulam and diuron, in the straw matrix, directly interfering with their availability in the environment. This process can reduce the herbicide environmental risk but can decrease weed control efficiency.

O sistema de rotação de culturas tem trazidos vários benefícios tanto para o produtor quanto para o solo. Entretanto o sistema de rotação de cultura da canola com a soja pode causar danos na germinação e no desenvolvimento de plantas de soja, devido à liberação de compostos alelopáticos liberados pela palhada da canola. Diante disso, esse trabalho tem como objetivo realizar uma revisão bibliográfica apresentado alguns resultados encontrados na literatura para diminuir os efeitos negativos causados pela alelopatia da cultura da canola sobre a cultura da soja. Essas informações serão de suma importância para os produtores, auxiliando na redução do efeito alelopático e na diversificação de renda do produtor. O trabalho teve como conclusão de que a mistura de inoculantes Bradyrhizobium japonicum associado ao cobalto e molibdênio tem maior capacidade de reduzir os efeitos alelopáticos. Além disso, algumas cultivares de soja são mais suscetíveis a esses compostos comparadas a outras.

A mistura de tanque com a utilizando adubos foliares e herbicidas atualmente é liberada no Brasil sendo comum para as maiores da cultura, trazendo como principais vantagens um custo reduzido e uma menor compactação no solo. Desse modo, esse trabalho tem como objetivo realizar uma revisão bibliográfica apresentado alguns resultados encontrados na literatura para os principais ingredientes ativos (glifosato, 2,4-D e atrazina) com adição de adubos foliares utilizados nos sistemas de manejo do Brasil. Resultados que podem auxiliar os produtores na busca de potencializar o uso desses herbicidas em misturas de tanques, diminuindo o custo operacional e compactando menos o solo. As interações física e química entre os herbicidas e adubos foliares pode acarretar efeito aditivo, sinérgicos ou antagônicos, o impulsiona na realização de estudos para analisar o comportamento da planta. O trabalho teve como conclusão que alguns elementos minerais podem interferir na absorção da planta sobre o herbicida. Além disso, alguns micronutrientes podem potencializar a absorção dos herbicidas na plantas e ainda que as culturas não sofram com deficiência nutricional.

No abstract

The evolution of herbicide-resistant weeds is the major challenge for chemical management worldwide, increasing production costs, and reducing yield. This work aimed to evaluate the putative resistance of the Amaranthus hybridus population from Candido Mota (CMT) to glyphosate and imazethapyr and to investigate the non-target site mechanisms involved. Dose–response studies were conducted under greenhouse conditions and the control and biomass reduction were evaluated 28 days after application (DAA). Absorption, translocation, and metabolization studies were evaluated at 72 h after treatment (HAT) using radiometric techniques. The dose–response results show different responses among populations to glyphosate and imazethapyr. The CMT population was not controlled with labeled herbicide doses. Based on biomass reduction, the resistance factor was 16.4 and 9.4 to glyphosate and imazethapyr, respectively. The CMT absorbed 66% of 14C-glyphosate and 23% of 14C-imazethapyr at 72 HAT. Although the CMT population absorbed more glyphosate than the susceptible population (12.6%), translocation was impaired for both herbicides in the CMT when compared to the SUS population. There was no evidence that herbicide metabolization was involved in CMT resistance to the herbicides studied. Understanding the mechanisms endowing resistance allows better decision-making. This is the first study that describes non-target-site resistance mechanisms in an Amaranthus hybridus population from Brazil.

The knowledge of the adequate period for the beginning of weed management in lettuce crop can increase the efficiency of production, reducing the costs with management. The aim of this study was to determine the pre-interference period (PIP), the critical time for weed removal (CTWR) and the critical period of weed control (CPWC) in three lettuce cultivars, Elisa, Lucy Brown and Solaris. Coexistence and the absence of weeds were evaluated for each cultivar. The design was in randomized blocks with seven treatments (0, 7, 14, 21, 28, 35 and 42 days after transplanting - DAT) of coexistence and the same seven periods of weed absence with four replicates in each experiment. The highest infestation densities were with the species Oxalis latifolia, Coronopus didymus and Amaranthus hybridus. The leaf area and number of leaves per plant were reduced by up to 50% and 66%, respectively, in relation to the longest period of coexistence with weeds and yield reduced by 48% (Elisa), 40% (Lucy Brown) and 33% (Solaris). The cultivar Solaris showed greater tolerance to weed interference. Based on yield, PIP was 1, 3 and 3 DAT and CTWR was 37, 37 and 35 DAT, and CPWC was 2 to 37, 3 to 37 and 3 to 35 for the cultivars Elisa, Lucy Brown and Solaris, respectively.