Resumo -O objetivo deste trabalho foi avaliar o efeito de diferentes arranjos espaciais no desempenho agronômico de mucuna-verde (Mucuna pruriens var. utilis). O experimento consistiu de oito tratamentos, dispostos em delineamento de blocos ao acaso em arranjo fatorial 2x4, com quatro repetições. Os tratamentos foram semeadura da mucuna-verde, em dois espaçamentos entre sulcos de plantio (0,5 e 1,0 m) e quatro densidades de plantas (2, 4, 8 e 16 plantas m -1). Determinaram-se as taxas de cobertura do solo e de fixação biológica de nitrogênio (FBN) e a produção de matéria seca e a quantidade de N acumulado na parte aérea. A cobertura total do solo ocorreu aos 50 dias após a semeadura, na densidade de 16 plantas m -1 e espaçamento de 0,5 m entre sulcos de plantio. A combinação da densidade de 16 plantas m -1 com o espaçamento de 1,0 m entre sulcos proporcionou a maior produção de matéria seca e quantidade de N acumulado na parte aérea das plantas. Independentemente do arranjo espacial das plantas, a estimativa da FBN nesta espécie mostra que cerca de 70% do N presente na parte aérea é derivado da atmosfera.Termos para indexação: Mucuna pruriens var. utilis, adubo verde, fixação biológica de nitrogênio. Agronomic performance of velvet bean at different spatial arrangementAbstract -The objective of this work was to evaluate the effect of different plant spatial arrangements on agronomic performance of velvet-bean (Mucuna pruriens var. utilis). The experiment was performed with eight treatments, distributed in a randomized complete block design in a 2x4 factorial arrangement, with four replicates. The treatments were velvet bean sowing at two spacings between furrows (0.5 and 1.0 m) and four plant densities (2, 4, 8 and 16 plants m -1 ). Determinations were made for the soil covering and biological nitrogen fixation (BNF) rates, and for the dry matter yield and N accumulation in the plant shoots. Total soil cover was accomplished at 50 days after sowing at 16 plants m -1 density and 0.5 m spacing between furrows. The combination of 16 plants m -1 density with the 1.0 m spacing between furrows provided the greatest dry matter yield and accumulated most N in the plant shoots. Irrespective of the plant spatial arrangement, the estimation of BNF in this species shows that about 70% N present in the shoot is derived from the atmosphere.Index terms: Mucuna pruriens var. utilis, green manure, biological nitrogen fixation. IntroduçãoA adubação verde pode ser realizada com espécies de várias famílias botânicas, entre as quais se destacam as da família das leguminosas (Fabaceae). Além de proporcionar benefícios similares aos obtidos com espécies de outras famílias, as leguminosas têm como particularidade o fato de formar associações simbióticas com bactérias dos gêneros Rhizobium e Bradyhizobium, fixadoras de nitrogênio atmosférico. Como resultado da simbiose, quantidades expressivas de nitrogênio (N) tornam-se disponíveis após o corte da leguminosa, o que acarreta auto-suficiência em N, se a planta for adequadamente manejada ...

The work was carried out in nursery of the Agronomical Science College (ASC) UNESP-Botucatu, in period from September 21 st to October 31 st 2000. The propagation material (rhizophores) was obtained from plants, which were cultivated in the area of ASC. The rhizophores were selected according to their vigor and size. Healthy rhizophores were chosen between 15 and 25 g, which were treated with benomil (0,6 %, 10 minutes). As a basic commercial substratum Solomix® was used with mixing cattle manure and chicken manure in the following proportions: T1-pure substratum; T2 -substratum + cattle manure (1:1), T3-substratum + cattle manure (2:1); T4-substratum + chicken manure (4:1). The yacon rhizophores presented good shoots in all substrata with exception of T4. For all parameters no significant difference between the pure commercial substratum and its mixture with cattle manure were observed; however, the addition the chicken manure in the studied proportions revealed harmful effect on the survival and development of the plantlets. The results indicated, that the viability of smaller size rhizophores was higher as the size conventionally used in Brazil (60 to 80 g). * Data followed by the same letter, in the column, doesn't differ to each other at 5% of probability for the Tukey test.