Early Root and Shoot Development of Nine Plant Species

Abstract

The root growth rate index of velvetleaf (Abutilon theophrastiMedic.) was significantly greater than that of five other weed species. The root growth rate index of sorghum [Sorghum bicolor(L.) Moench ‘RS-626’] was found to be significantly higher than that of soybeans [Glycine max(L.) Merr. ‘Ford’]. Shoot growth rate indexes of three perennial broadleaf species studied were significantly lower than shoot growth rate indexes of six annual species. Root weights of perennial broadleaf species were not significantly different from root weights of velvetleaf and soybeans. Soybeans were found to have a significantly higher shoot to root ratio than seven weed species but not higher than sorghum. All other species had larger leaf weights and leaf areas than the three broadleaf perennials. While there were significant differences in leaf weights among six species, there were no significant differences in leaf area. Seed weight was not significantly correlated with emergence rate index and root weight but was correlated to all other factors studied. Emergence rate index was correlated with root growth rate index but not with shoot growth rate index.

Velvetleaf (Abutilon theophrasti) Effect on Corn (Zea mays) Growth and Yield in South Dakota

“…Velvetleaf stem diameter 10 cm above the soil was measured with calipers in mid-August when com was in the dough stage of growth. All com and velvetleaf material (including overlapping leaves in a 1-m by 0.76-m section of row) was harvested for leaf area index (LAI) 4 and biomass measure ments on Aug. 12 and 17,1992 at Brookings and Beresford, respectively, and Aug. 19, 1993. Leaf area was measured with an automated leaf area meter.…”

“…Shad ing reduces com photosynthesis, decreasing the amount of photosynthate available for yield (7). Fibrous velvetleaf roots compete with com roots for soil water and nutrients at similar depths (4). Com yield reduction by velvetleaf is directly related to com and velvetleaf time of emergence, velvetleaf density, and duration of velvetleaf interference (10).…”

The biology of Johnson grass (Sorghum halepense)

“…Leaf growth is slow during this period. After formation of the rhizome spur, leaf growth is rapid, equalling or exceeding root growth, while rhizome production is low (McWhorter, 1961;Evetts & Burnside, 1973), Flowering commences 7 weeks after emergence and continues for the rest of the growing season. At flowering rhizome production increases rapidly (McWhorter, 1961), However, Horowitz (1972a found no causal relationship between flowering and rhizome formation.…”

Scaling plant size to below‐ground zone of influence in annuals under contrasting competitive environments

“…Average rates of VRG ranged between 0·88 and 1·49 cm day −1 , figures that are considerably smaller than those reported in previous studies (1·3–6·3 cm day −1 ) for annual weed species. However, in these earlier studies weed plants were grown in glass‐walled chambers where space for lateral root development was restricted (Wiese 1968; Evetts & Burnside 1973), and this may explain the higher rates of development than we observed in the vertical dimension in the field. The initial differences in VRG among weed species may be due, in part, to the smaller seed size ( A. retroflexus < C. album < S. faberi < A. theophrasti < maize) (Harbur & Owen 2004), and thus slower initial rates of whole plant growth (Wiese 1968).…”