Substrate and irrigation scheme on the growth of Parapiptadenia rigida seedlings/Diferentes substratos e regimes de rega no desenvolvimento de mudas de Parapiptadenia rigida

Parapiptadenia rigida (angico-vermelho) is a native arboreal species widely found in central and southern Brazil and is indicated for restoration of degraded areas due to its high plasticity to light gradients and ease adaptation to degraded environments. However, there is still a lack of information on this species regarding the production of quality seedlings, as well as the rational use of the resources involved. Thus, the objective of this study was to evaluate the effects of different substrates and irrigation schemes in the development of P. rigida seedlings. The experimental design used was randomized blocks, in a factorial scheme with split plots, with four substrate formulations (100% peat; 80% peat + 20% carbonized rice husk (CRH); 60% peat + 40% CRH; 40%peat + 60% CRH) and six irrigation schemes (4; 8; 12; 16; 20 and 24mm.[day.sup.-1]). At 180 days after emergence, the following parameters were evaluated: height, stem diameter, height and stem diameter ratio, shoot dry weight, root dry weight, total dry weight and Dickson Quality Index. Use of substrate composed of 80% peat + 20% carbonized rice husk and/or 100% peat, combined with irrigation scheme of 4mm [day.sup.-1], resulted in the best growth of P. rigida seedlings. Key words: Parapiptadenia rigida, irrigation, production of seedlings. Parapiptadenia rigida (angico-vermelho) e uma especie arborea nativa amplamente encontrada na regiao central e sul do Brasil, e indicadapara restauracao de areas degradadas em virtude de sua alta plasticidade a gradientes de luz e facilidade de adaptacao a ambientes degradados. No entanto, a especie ainda carece de informafoes no que se refere a producao de mudas de qualidade, bem como, a utilizacao de forma racional dos recursos envolvidos. Dessa forma, esse estudo teve por objetivo avaliar os efeitos de diferentes substratos e regimes de rega no desenvolvimento de mudas de P. rigida. O delineamento experimental utilizado foi blocos ao acaso, em esquema fatorial com parcela subdividida, considerando quatro formulafoes de substratos (100% turfa; 80% turfa + 20% casca de arroz carbonizada (CAC); 60% turfa + 40% CAC; 40% turfa + 60% CAC) e seis regimes de rega (4; 8; 12; 16; 20 e 24mm.[dia.sup.-1]). Aos 180 dias apos a emergencia, foram avaliados os seguintes parametros morfologicos: altura, diametro do coleto, relacao altura e diametro do coleto, massa seca aerea, massa seca radicular, massa seca total e indice de qualidade de Dickson. Constatou-se que a utili