Manejo agronômico da malva (Urena lobata L.) para produção de fibra no estado do Amazonas

Abstract

Malva (Urena lobata L.) is the main species used for the production of bast fiber in Brazil. It is traditionally cultivated by smallholder farmers in the floodplains of the Amazon and Solimões Rivers. Over the past two decades, local production has declined sharply and currently supplies less than 30% of national demand. The adoption of improved cultivation techniques in floodplain areas and the expansion of malva farming to terra firme (non-flooded upland soils) are promising strategies to increase production in the medium term. This dissertation aimed to evaluate agronomic management practices for malva fiber production in both floodplain and terra firme environments in the state of Amazonas. Three fields experiments were conducted: one in the floodplain of the Solimões River and two in terra firme areas at the UFAM Experimental Farm. These trials investigated the effects of planting spacing, liming, and phosphorus fertilization in malva cultivation for fiber production. Malva responded positively to increased planting density under standardized spacing, with fiber productivity rising as plant density increased, both in floodplain and terra firme conditions. In acidic, dystrophic, and phosphorus-deficient soils typical of the Amazon region, phosphorus fertilization at sowing was essential for plant establishment and vegetative development under closely spaced planting. When combined with liming, it significantly enhanced aboveground biomass accumulation and fiber yield. This research presents novel insights into the morpho-agronomic traits, dry matter yield, biomass allocation, and fiber productivity of malva in response to planting spacing, liming, and fertilization.