The effects of the coexistence of weed communities on table beet yield during early crop development/Efeitos de convivencia da comunidade de plantas daninhas na producao de beterraba durante o desenvolvimento inicial da cultura

• Published in: Acta scientiarum. Agronomy 2010-10, Vol.32 (4), p.709-714
• Main Authors: Carvalho, Leonardo Bianco, Guzzo, Caio Doria, Pitelli, Robinson Antonio, Filho, Arthur Bernardes Cecilio, Bianco, Silvano
• Format: Article
• Language: eng ; spa
• Subjects: Beta vulgaris; direct seeding; interference; interferência; plantas daninhas; seedling transplanting; semeadura direta; transplante de mudas; weeds
• ISSN: 1679-9275; 1807-8621
• DOI: 10.4025/actasciagron.v32i4.4649

The objective was to evaluate the effects of initial weedy periods on the weed community and on the productivity of direct seeded and transplanted table beet cropping systems. A field trial was conducted at Sao Paulo State University, Brazil, in a randomized complete block design using a 2 x 13 factorial scheme. Direct seeding and seedling transplanting methods were evaluated within thirteen increasing weekly weedy periods. Weed relative importance was calculated and weed density and weed dry matter accumulation data were analyzed by nonlinear regression as well as beet yield and stand, which were submitted to analysis of variance. Amaranthus viridis, Coronopus didymus, Cyperus rotundus, Digitaria nuda, Galinsoga parviflora and Nicandra physaloides were the most important weeds found, with special reference to C. didymus. Weed dry matter accumulation was greater in the direct seeded crop, although weed density was higher in the transplanted crop. Transplanted beet yield was greater than of direct seeded beet in the weed-free treatment during the whole crop cycle. Crop-weed coexistence could remain for four and seven weeks after seeding/transplanting in direct seeded and in transplanted beet, respectively, before reducing yield economically. Thus, direct seeded crop was more susceptible to weed interference than the transplanted one. Key words: Beta vulgaris, weeds, interference, direct seeding, seedling transplanting. Objetivando avaliar efeitos de periodos de infestacao inicial na comunidade infestante e na produtividade da beterraba em sistema de semeadura direta e transplantio, conduziu-se um experimento em delineamento de blocos casualizados, esquema fatorial 2 x 13. Metodos de semeadura direta e transplante de mudas foram avaliados dentro de 13 periodos semanais crescentes de infestacao. Importancia relativa, densidade e materia seca acumulada pelas plantas daninhas foram analisadas por regressao nao-linear, assim como produtividade e estande da cultura de beterraba, que foram submetidos a analise de variancia. Amaranthus viridis, Coronopus didymus, Cyperus rotundus, Digitaria nuda, Galinsoga parviflora e Nicandra physaloides foram as plantas daninhas mais importantes, destacando-se C. didymus. O acumulo de materia seca das plantas daninhas foi maior na cultura em semeadura direta, embora a densidade de plantas daninhas tenha sido mais alta em sistema de transplantio. A produtividade da beterraba transplantada foi maior que a da semeadura direta no tr