A study of the growth and development of Polygonum aviculare
Abstract
Laboratory experiments were carried out to investigate the dormancy and after-ripening requirements of mature Polygonum aviculare seed. Approximately 90% of the mature seed sample tested was shed with an innate dormancy preventing immediate germination. Storage at 4°C resulted in the release of this innate dormancy, although individual seeds showed subtle differences in their after-ripening requirements.
Further studies were carried out in the field to investigate the periodicity of germination of P. aviculare seed and the influence of variable light intensities on vegetative and reproductive growth of the weed.
The emergence of P. aviculare seed that was buried in the field at four different depths during winter, was observed in early spring. Non-germinating seed was retrieved the following winter and showed 96% germination when placed in suitable conditions. Depth of burial affected seed emergence, with maximum emergence occurring at 1 cm and the lowest at 10 cm.
P. aviculare growth and development was investigated at four light intensities; full, 47%, 23% and 7% daylight. Dry weight, leaf area and weight of seed produced per plant were significantly reduced at each light level below full daylight. Growth analysis showed that the relative growth rate at full daylight was high and similar to other annual weed species. It also appeared that P. aviculare partially compensated for lowered light intensities by increasing specific leaf area and stem weight ratio while the leaf weight ratio remained unaltered. Despite the severely retarded vegetative growth at 7% daylight, the plant still ripened seed.
The results attained in this study suggest that the early spring germination habit of the seed controlled by an environmentally modified dormancy, the high relative growth rate, the ability to survive at low light levels and yet produce seed, are all factors contributing to the presence and difficulties in controlling P. aviculare in arable land.
