ABSTRACT
Known locally as embauba, Cecropia pachystachya Trécul is a rustic, pioneer species with fast growth, ideal for cultivation in soils of low fertility, which explains its dependence on arbuscular mycorrhizal fungi (AMF). The symbiosis of this plant with AMF increases its efficiency in absorbing nutrients from the soil solution, especially those of low mobility such as phosphorus, which makes it possible to use phosphate fertilisers of low solubility in the production of seedlings. To evaluate this possibility, work was carried out in a greenhouse for 120 days, where natural rock phosphate was tested at five doses of P (0, 75, 150, 300 and 600 mg L-1) for colonisation by AMF. Also tested was the development of embauba seedlings grown in a substrate comprising natural soil (SN), natural soil with 50% (v/v) sterilised soil (SND), and natural soil with 25% (v/v) organic material (SNM). Evaluations were made of height, shoot dry weight production, stem diameter, levels of N, P, K, percentage mycorrhizal root colonisation, number of AMF spores in the substrate, soil basal respiration (RBS), microbial biomass carbon (CBM) and soil metabolic quotient (qCO2 ). Growth, stem diameter and shoot dry matter in the embauba were not benefitted by the substrates or the levels of P. However, root mycorrhizal colonisation, sporulation, RBS, CBM and qCO2 were affected by the phosphorus and organic fertilisers added to the soil.
Key words:
Cecropia pachystachya Trécul. Phosphorus. Mycorrhiza; Organic fertiliser
