Showing papers on "Plant morphology published in 2002"

Interactive effects of lateral shade and wind on stem allometry, biomass allocation, and mechanical stability in Abutilon theophrasti (Malvaceae).

Abstract: The effects of lateral shade and wind on stem allometry, whole-plant biomass allocation, and mechanical stability were examined for Abutilon theophrasti in a fully factorial glasshouse experiment. Lateral shade from neighboring plants increased stem height by 33% relative to control plants grown individually, despite a decrease in plant dry mass. Intermittent wind decreased stem height by 18% in unshaded plants, but by only 3% in shaded plants. Surprisingly, both lateral shade and wind caused decreases in stem diameter, even with diameter controlled for height, resulting in low diameter : height ratios in wind-treated plants relative to untreated plants. Under shade, wind-treated plants had higher root allocation than untreated plants, which allowed wind-treated shade plants to compensate for a low diameter : height ratio. This did not occur in the absence of shade, where stem tissue density and root allocation of wind-treated plants did not exceed that of untreated plants. Nevertheless, wind-treated plants experienced low drag relative to untreated plants due to a lower leaf area. Consequently, stem deflections of wind-treated plants did not exceed those of untreated plants at any given windspeed. Our results document a complex interaction between shade and wind on plant morphology and suggest that the nature of this interaction is generally that lateral shade acts to reduce or eliminate thigmomorphogenic responses.

Plant Population Effects on Fibre Hemp Morphology and Production

Abstract: This paper reports on a 4-year study into the effect of plant density on the morphology and production of fibre hemp. At high density (180-270 plants m2), strong competition for light early in the growing season promoted internode extension (primary growth) and inhibited increase of stem diameter (secondary growth). In relating plant density to fibre hemp production it can therefore be said that a high plant population favours a high yield of long bast fibres for the textile industry. Demands only for high total yield can however be satisfied by targeting 30-45 plants mr2. This is further supported by results of self-thinning, showing plant loss in 1999 was negligible at low density (30-90 plants m2), while at high density (180 and 270 plants m2) 50% and 60% of the initial stand was lost, respectively. In view of this result, and because of the fact that no significant morphological difference was found between 180 and 270 plants m2, it is also worth to note that when growing for long bast fibres...

Classification of Italian Xanthium strumarium complex based on biological traits, electrophoretic analysis and response to maize interference.

Abstract: Xanthium strumarium complex was studied taking plant seeds from 16 diverse locations in Italy. Plant morphophysiological traits were noted and electrophoretical analysis of seed reserve proteins was carried out from individual plants grown at the same site, in the presence and absence of competition from maize. Significant correlations between diverse plant phenological traits, the geographical origin of the seeds and the seed protein electrophoretic patterns were found. A high correlation between seed reserve proteins and the genetic structure of this weed was also detected. Maize competition increased Xanthium stem growth and decreased bur production and number of branches. Xanthium plant populations could be classified according to the morphological characters evaluated in three groups closely related to their geographical original area and latitude (northern, central and southern Italy), each showing precise morphological traits of Xanthium italicum, X. strumarium and X. orientale respectively. Electrophoresis supported the classification of these three morphological groups.

Seed and seedling morphology, and seed anatomy of Lasiopetaleae (Malvaceae s.l. or Sterculiaceae)

Abstract: Seed and seedling morphology and seed anatomy of Lasiopetaleae sensu Whitlock et al. (Malvaceae s.l.) and related genera are described. All seed of Lasiopetaleae, except Maxwellia, have arils that develop adjacent to the funicle. Some species have flexible, stellate hairs on their seeds. Seed size, shape, aril form, presence of hair and exotesta pattern can be definitive at generic and/or specific levels.