Variabilidade da infestação em duas variedades de trigo mole (Triticum Aestivum L.). I – em função da data de sementeira e do controlo das plantas infestantes em pós-emergência

Variability of weed infestation in two wheat varieties (Triticum Aestivum L.). I - as influenced by sowing date and post-emergence weed control

José Manuel Godinho Calado^{1 (2)}; Gottlieb Basch^{1 (2)}, Mário de Carvalho^{1 (2)}

RESUMO

Neste trabalho, procurou-se verificar a influência da data de sementeira e do controlo das infestantes na infestação e na produção de duas variedades de trigo mole (Sever e Centauro), a partir de um ensaio instalado durante quatro anos (1996/97 a 1999/00) na Herdade da Revelheira, concelho de Reguengos de Monsaraz.

De acordo com a análise dos resultados, constatou-se que a sementeira do trigo efectuada no início de Novembro permitiu a ocorrência de maior infestação na cultura relativamente à realizada no fim de Novembro e, em consequência, as perdas de produção do trigo sem aplicação de um herbicida em pós-emergência foram maiores. Portanto, a aplicação de um herbicida em pós-sementeira, nas condições mediterrânicas do Sul de Porugal, é mais relevante para diminuir a infestação e as perdas produtivas do trigo quando a sementeira é precoce (realizada no início de Novembro).

Palavras-chave: data de sementeira do trigo, gestão de plantas infestantes.

 

ABSTRACT

The density of weed infestation of a crop is influenced by its sowing date due the variability of the control of the spontaneous flora in pre-emergence, depending on the level of weed emergence before sowing.

In this study the effect of different sowing dates of two wheat varieties (Sever and Centauro) and post-emergence weed control was analyzed in terms of weed infestation and crop performance. The trials were carried out over four years (1996/97 until 1999/00) on the farm “Revelheira” belonging to the Regional Directorate of Agriculture in the Reguengos de Monsaraz municipality.

When sowing was carried out in the beginning of November and without post-emergence weed control weed infestation during the crop cycle was much higher when compared to the sowing date at the end of November. Consequently, yield reduction was much more pronounced at the early sowing date. Thus, for early sowing dates, post-emergence weed control under Mediterranean conditions seems to be essential to avoid severe weed infestation and unacceptable crop yield reductions.

Key-words: sowing date, weed management, wheat.

 

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¹Universidade de Évora, Departamento de Fitotecnia, Apartado 94, 7002-554 Évora E-mail: jcalado@dfit.uevora.pt.

²Instituto de Ciências Agrárias Mediterrânicas. Apartado 94, 7002-554 - Évora E-mail: icam@uevora.pt

 

Recepção/Reception: 2006.11.16

Aceitação/Acception: 2007.06.25