Dissulfeto de dialila no controle de Meloidogyne incognita em alface e (R)-carvona no manejo de plantas daninhas.

Abstract

Lettuce (Lactuca sativa L.) is a vegetable crop of considerable socioeconomic importance in Brazilian agriculture. However, its production faces significant challenges, particularly damage caused by plant-parasitic nematodes, specifically Meloidogyne incognita, and competition from weeds. Given the absence of registered chemical nematicides for lettuce and the need to reduce dependence on conventional synthetic inputs, this study evaluated the efficacy of compounds derived from Allium sativum (diallyl disulfide, DADS) and Menthaspp. (R)-carvone) as alternative management strategies. The experiments were conducted at the Center for Development and Technology Transfer (CDTT/UFLA), located in Ijaci, Minas Gerais, Brazil. A randomized complete block design was adopted, consisting of four treatments with six replicates: diallyl disulfide (DADS), (R)-carvone, an untreated control (water), and a commercial metam sodium-based product. Evaluations were performed 45 days after treatment application and included the number of M. incognita eggs per gram of root, as well as the fresh biomass of shoots and roots. For weed assessment, soil samples were collected from the experimental plots, homogenized, and placed under greenhouse conditions for subsequent species identification and analysis of diversity indices (ShannonWiener, Richness, and Evenness). The results demonstrated that DADS exhibited nematicidal activity, significantly reducing the number of eggs per gram of root (by 48% to 65%), with performance statistically comparable to that of the commercial product. In contrast, (R)-carvone did not provide significant nematode control, remaining statistically similar to the untreated control. Regarding plant growth parameters, metam sodium promoted the greatest increases in shoot and root fresh biomass. Although DADS and (R)-carvone produced intermediate results, both significantly outperformed the untreated control. In weed management, metam sodium inhibited seed germination by more than 99% and significantly reduced all diversity indices. (R)-Carvone reduced weed germination by 71.36%, whereas DADS achieved a 43.65% reduction, without significantly altering the diversity of the weed community relative to the untreated control. These findings indicate that DADS represents a promising alternative for the management of M. incognita, while (R)-carvone stands out for its high herbicidal potential, supporting the use of plant-derived compounds as sustainable tools for the integrated management of lettuce crops.