Study on Population Density and Mulch Effectiveness in Early Growth of Onions Seedlings and Weed Dynamics

Onion cultivation (Allium cepa), known as "bawang Bombai,"is relatively new in Indonesia, a tropical region. It can be done using transplanting or direct seed planting (DSP). Farmers favor DSP as it eliminates the need for a separate nursery; however, optimal seedling density and effective weed control are crucial during the early growth stages. This study, conducted in Yogyakarta from May to July 2024, investigated the impact of onion seedling density and mulch on early growth using DSP. The experimental design features a split-plot arrangement with four replications. The main plot involved the mulch treatments (none and plastic mulch), while the subplot examined seedling densities (2, 4, 6, and 8 g per m2). Results showed no interaction between seedling density and mulch on any variables. Treatments did not significantly affect seedling emergence, plant height, or leaf number. Plastic mulch reduced total weed emergence, but the difference was not significant compared to no mulch during the early growth phase. However, higher seedling densities could suppress total weed emergence. Eleusine indica and Portulaca oleracea were the dominant weed species during the early growth stage. Plastic mulch was only effective in suppressing the emergence of Eleusine indica. In contrast, Portulaca oleracea emergence could not be suppressed by either plastic mulch or increased seedling density in the bed. The findings suggest that using plastic mulch can effectively manage weeds in an early growth phase, particularly Eleusine indica, making this practice beneficial for farmers. © 2025 Published under licence by IOP Publishing Ltd.