Introduction

The temperature of the spray solution stands as a pivotal factor in formulating effective weed management strategies, particularly within the context of agricultural systems in temperate and warm regions. Variations in temperature can significantly influence the physical and chemical properties of herbicide formulations, thereby affecting the penetration rate and absorption efficiency of herbicides by summer broadleaf weeds. Glufosinate is a widely used post-emergence contact herbicide. Its efficacy is known to be directly influenced by environmental conditions, making the understanding of the relationship between spray solution temperature and the effectiveness of this herbicide crucial for developing more precise and efficient weed management protocols. Considering that weeds such as common purslane (Portulaca oleracea L.) and ground cherry (Physalis divaricata L.) are recognized as problematic and resistant species in numerous agricultural fields, investigating the factors that contribute to their effective control holds particular importance. This study was designed to comprehensively explore how different spray solution temperatures, in conjunction with the application of glufosinate and a specific adjuvant, impact the control of these two summer broadleaf weeds.



Materials and Methods

This research was conducted as a dose-response experiment employing a completely randomized design in a factorial arrangement. The study aimed to evaluate the impact of six different doses of glufosinate herbicide across five distinct temperature levels of the spray solution: 4°C, 19°C, 32°C, 46°C, and 58°C. The experiment was carried out on two summer broadleaf weeds, common purslane (Portulaca oleracea L.) and ground cherry (Physalis divaricata L.), with three replications for each treatment combination. The treatments were applied both as a pure herbicide solution and in a mixture with the surfactant “GyasidPlus”. The collected data were subjected to Analysis of Variance (ANOVA) to determine the significance of the main effects and their interactions. Furthermore, a three-parameter log-logistic equation was fitted to the data to estimate the effective doses (ED10, ED50, and ED90), representing the doses required for 10%, 50%, and 90% growth reduction, respectively. This methodological approach enabled a precise comparison of the effects of temperature and the adjuvant on herbicide efficacy.



Results and Discussion

The ANOVA results revealed a highly significant effect (P<0.01) of both varying glufosinate doses and different temperature treatments on the fresh weight of both purslane and groundcherry weeds. The lowest herbicidal efficacy was observed when all doses of glufosinate were applied at the cold temperature of 4°C, indicating a significant reduction in the herbicide’s performance under suboptimal thermal conditions. Moderate yet significant effects were obtained from the application of different glufosinate doses at temperatures of 19°C and 58°C. However, the most favorable conditions for enhancing glufosinate efficacy were identified at thermal levels of 32°C and 46°C. This strongly suggests a clear temperature-dependent response of glufosinate activity, with an optimal range for its action. The co-application of all treatments with the GyasidPlus surfactant led to a significant increase in the efficacy of glufosinate across all temperature conditions, which was further evidenced by the reduction in the calculated ED values. This enhancement is likely attributable to the surfactant’s role in improving spray retention, spreading, and penetration of the herbicide into the plant tissues, thereby optimizing its contact action. These findings align with previous research highlighting the importance of environmental factors and formulation components in determining herbicide performance.



Conclusion

In conclusion, this study demonstrates that the temperature of the spray solution plays a critical role in the herbicidal activity of glufosinate against summer broadleaf weeds, common purslane and ground cherry. The optimal temperature range for achieving satisfactory control with glufosinate was found to be between 19°C and 46°C. Temperatures significantly below or above this range led to a noticeable decrease in herbicide efficacy. Furthermore, the inclusion of the surfactant GyasidPlus consistently improved glufosinate performance under all tested temperature regimes, significantly reducing the required doses for effective weed control. Therefore, the most effective treatment recommended for managing these two summer broadleaf weeds involves the application of 2050 g a.i. ha-1 of glufosinate in combination with the GyasidPlus surfactant, applied within the optimal temperature window. This integrated approach, considering both herbicide dose, adjuvant use, and environmental temperature, offers a more robust and efficient strategy for sustainable weed management in agricultural systems.