In 1995 and 1996, an annual species growing in maize (Zea mays L.) fields near Torino, Vercelli and Novara, was identified as Polygonum orientale L., a species anciently grown as an ornamental plant and sometimes reported to run wild. The study was aimed at defining the main morphological traits of P. orientale plants growing in a natural weed community infesting maize. In a maize field located near Torino, where P. orientale showed a uniform plant density of 1.8 plants m-2, 4 plots of 8 m2 were marked out in 1996. Two whole plants were dug up from each plot at flowering stage and partitioned into roots, stems, leaves, inflorescences and seeds. These plant portions were then separately counted, weighed and measured. The species, not much shorter than maize (2.7 m, on average), presented numerous branches (10 - 44) of decreasing length from the basal to the upper stem portion (from 0.85 m to 0.11 m, on average). The leaf area ranged from 263 to 14 cm2 in the basal and upper part of the plant, respectively. Inflorescences appeared gradually at the end of each branch, at the time of maize panicle emission, and produced as many as 10,000 seeds per plant. The plant allocated about 80% of the dry biomass to epigean tissues. The morphological characterization of P. orientale showed features, such as plant height, seed production and leaf area, which could favour the species spreading in cultivated fields. It therefore seems necessary to follow the possible diffusion of the plant in the areas where it was reported, in order to evaluate if the species is a garden escape or a plant able to invade the crops in a stable manner.
Biometrical traits of Polygonum orientale, a potential weed in Italian maize fields
FERRERO, Aldo;VIDOTTO, Francesco
1998-01-01
Abstract
In 1995 and 1996, an annual species growing in maize (Zea mays L.) fields near Torino, Vercelli and Novara, was identified as Polygonum orientale L., a species anciently grown as an ornamental plant and sometimes reported to run wild. The study was aimed at defining the main morphological traits of P. orientale plants growing in a natural weed community infesting maize. In a maize field located near Torino, where P. orientale showed a uniform plant density of 1.8 plants m-2, 4 plots of 8 m2 were marked out in 1996. Two whole plants were dug up from each plot at flowering stage and partitioned into roots, stems, leaves, inflorescences and seeds. These plant portions were then separately counted, weighed and measured. The species, not much shorter than maize (2.7 m, on average), presented numerous branches (10 - 44) of decreasing length from the basal to the upper stem portion (from 0.85 m to 0.11 m, on average). The leaf area ranged from 263 to 14 cm2 in the basal and upper part of the plant, respectively. Inflorescences appeared gradually at the end of each branch, at the time of maize panicle emission, and produced as many as 10,000 seeds per plant. The plant allocated about 80% of the dry biomass to epigean tissues. The morphological characterization of P. orientale showed features, such as plant height, seed production and leaf area, which could favour the species spreading in cultivated fields. It therefore seems necessary to follow the possible diffusion of the plant in the areas where it was reported, in order to evaluate if the species is a garden escape or a plant able to invade the crops in a stable manner.
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