Orange peels and shrimp shell used in a fermentation process to produce an aqueous extract with bioherbicide potential to weed control

Efficacy of pre-harvest weed control treatments on onion bulb storability

Storage experiments were carried out, in 2019 and 2020, to evaluate the effect of pre-harvest weed control treatments on quality attributes and storability of onion bulbs during a six-month storage at room temperature (25 ± 5 °C and 50-60% relative humidity) in corrugated paper boxes. Weed control treatments consisted of the aqueous extracts of orange peel processing waste (OPPW) 20%, mango leaves waste (MLW) 30%, and olive oil processing waste (OOPW) 30%, alone or mixed with half a dose of oxyfluorfen herbicide (938 ml ha-1), soil mulching with orange peel processing waste, mango leaves, olive oil processing waste, and rice straw (OPPWM, OOPWM, MLW, and RSM, respectively) at 10 tons ha-1, hoeing, oxyfluorfen herbicide (at 938 and 1875 ml ha-1), and an unweeded control treatment. OPPW mulch and hoeing treatments were the most effective treatments in improving storability, decreasing weight loss and decay percentages of onion bulbs as well as maintaining bulb quality attributes, i.e., bulb firmness, dry matter, total soluble solids and total soluble sugars content during a six-months storage. It was concluded that using OPPW and MLW, as soil mulches or as aqueous extracts, for weed control within onion field, helps maintain onion bulb quality, and storability.

Microbial Bioherbicides Based on Cell-Free Phytotoxic Metabolites: Analysis and Perspectives on Their Application in Weed Control as an Innovative Sustainable Solution

Weeds cause significant agricultural losses worldwide, and herbicides have traditionally been the main solution to this problem. However, the extensive use of herbicides has led to multiple cases of weed resistance, which could generate an increase in the application concentration and consequently a higher persistence in the environment, hindering natural degradation processes. Consequently, more environmentally friendly alternatives, such as microbial bioherbicides, have been sought. Although these bioherbicides are promising, their efficacy remains a challenge, as evidenced by their limited commercial and industrial production. This article reviews the current status of microbial-based bioherbicides and highlights the potential of cell-free metabolites to improve their efficacy and commercial attractiveness. Stirred tank bioreactors are identified as the most widely used for production-scale submerged fermentation. In addition, the use of alternative carbon and nitrogen sources, such as industrial waste, supports the circular economy. Furthermore, this article discusses the optimization of downstream processes using bioprospecting and in silico technologies to identify target metabolites, which leads to more precise and efficient production strategies. Bacterial bioherbicides, particularly those derived from Pseudomonas and Xanthomonas, and fungal bioherbicides from genera such as Alternaria, Colletotrichum, Trichoderma and Phoma, show significant potential. Nevertheless, limitations such as their restricted range of action, their persistence in the environment, and regulatory issues restrict their commercial availability. The utilization of cell-free microbial metabolites is proposed as a promising solution due to their simpler handling and application. In addition, modern technologies, including encapsulation and integrated management with chemical herbicides, are investigated to enhance the efficacy and sustainability of bioherbicides.

Fungus-based bioherbicides on circular economy

This review aimed to show that bioherbicides are possible in organic agriculture as natural compounds from fungi and metabolites produced by them. It is discussed that new formulations must be developed to improve field stability and enable the commercialization of microbial herbicides. Due to these bottlenecks, it is crucial to advance the bioprocesses behind the formulation and fermentation of bio-based herbicides, scaling up, strategies for field application, and the potential of bioherbicides in the global market. In this sense, it proposed insights for modern agriculture based on sustainable development and circular economy, precisely the formulation, scale-up, and field application of microbial bioherbicides.