Biodegradable Spray Mulch Applications in Greenhouse Agroecosystems.

The replacement of synthetic chemical herbicides and traditional plastic sheets is a major challenge of modern horticulture in view of a sustainable weed management. In the first step of this research, we tested the weed control efficacy of two biodegradable polymers, chitosan and galactomannan, applied to the soil surface as spray mulching, with or without the addition of charcoal as a light masking agent, and five essential oils with recognized herbicide properties. The results showed the ability of chitosan in reducing the number and the biomass of annual plants, regardless of the addition of charcoal and essential oils. In the second step, we tested the efficacy of one or three days of false seeding to increase the effectiveness of chitosan against seed germination. The results showed, on average, a reduction of 79% of annual weed presence after three days of false seeding. In both steps, the microbial biomass and three indicators of microbial activity (i.e., basal respiration, FDA hydrolysis activity, and D-glucosamine-induced respiration) were measured in the soil under the experiments in order to investigate possible alterations of soil biological activity induced by the treatments. The results provided no evidence of negative impact of the treatments on soil microbial biomass and activity. [ABSTRACT FROM AUTHOR]