Resumo

Schizolobium parahyba (Vell.) S.F. Blake var. parahyba (known as guapuruvu), a pioneer leguminous, has potential to be used as a source of wood and/or in revegetation program. The use of growth-promoters microorganism as inocula should be considered as a technological improvement applied in intensive silviculture that use N-fixing bacteria and arbuscular mycorrhizal fungi (AMF) to increase wood production. The aim was to test plant growth and survival of Schizolobium parahyba inoculated with the arbuscular mycorrhiza fungi (AMF) Glomus clarum and N-fixing bacteria Rhizobium sp. The inocula was 10 g of soil colonized with Glomus clarum and/or 1 mL of cell suspension (107 CFU/mL) of Rhizobium sp. and/or 100 g of chemical fertilizer NPK 20-05-20 per planting hole. The experimental design was a complete randomized blocks arranged in a factorial treatment combination with five replications and eight treatments (n = 800): 1.Control; 2.Rhizobium; 3.G. clarum; 4.Fertilizer; 5.Rhizobium + fertilizer, 6.Rhizobium + G. clarum; 7.G. clarum + fertilizer; 8.Rhizobium + G. clarum + fertilizer. Plant height, stem diameter and plant survival were measured at 30, 60, 120,180 and 240 days, except stem diameter that was measured only at 180 and 240 days. The results were tested for normality and homogeneity of variances and analyzed by ANOVA and Tukey test (p < 0.05). Rhizobium and AM fungi showed no effect on plant growth. Environmental factors probably influenced the effectiveness of symbiosis with microorganisms and in plant growth. The high level of P found in the soil (24.0 mg dmˉ³) probably influenced the activity of AM fungi. Also the low pH 4,5 in the experimental soil may have influenced the establishment of the symbiosis between G. clarum/Rhizobium and plant. The chemical fertilizer increased plant growth of S. parahyba. During the first 120 days plants suffered with drought and frost. At 180 days plants inoculated with microorganism plus chemical fertilizer showed higher survival when compared with control. The results showed that the microbial inoculants used had an important role in plant survival after high stress conditions, but not in plant growth.