Cumulative Root Length Research Articles

Relationships among root branch order, carbon, and nitrogen in four temperate species.

The objective of this study was to examine how root length, diameter, specific root length, and root carbon and nitrogen concentrations were related to root branching patterns. The branching root systems of two temperate tree species, Acer saccharum Marsh. and Fraxinus americana L., and two perennial herbs from horizontal rhizomes, Hydrophyllum canadense L. and Viola pubescens Ait., were quantified by dissecting entire root systems collected from the understory of an A. saccharum-Fagus grandifolia Ehrh. forest. The root systems of each species grew according to a simple branching process, with laterals emerging from the main roots some distance behind the tip. Root systems normally consisted of only 4-6 branches (orders). Root diameter, length, and number of branches declined with increasing order and there were significant differences among species. Specific root length increased with order in all species. Nitrogen concentration increased with order in the trees, but remained constant in the perennial herbs. More than 75% of the cumulative root length of tree seedling root systems was accounted for by short (2-10 mm) lateral roots almost always <0.3 mm in diameter. Simple assumptions suggest that many tree roots normally considered part of the dynamic fine-root pool (e.g., all roots <2.0 mm in diameter) are too large to exhibit rapid rates of production and mortality. The smallest tree roots may be the least expensive to construct but the most expensive to maintain based on an increase in N concentration with order.

St. Augustinegrass Rooting following Preemergence Herbicide Application

Greenhouse studies were conducted at the Univ. of Florida to evaluate the effects of preemergence herbicides on St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] rooting. Metolachlor, atrazine, metolachlor + atrazine, isoxahen, pendimethalin, dithiopyr, and oxadiazon were applied to soil columns followed by placement of St. Augustinegrass sod on the treated soil. Root elongation and biomass were measured following application. Plants treated with dithiopyr and pendimethalin had no measurable root elongation and root biomass was severely (&gt;70%) reduced at the study's conclusion (33 days). Root biomass was unaffected following isoxaben and oxadiazon treatments, but oxadiazon applied at 3.4 kg·ha-1 reduced root length by 50%. Atrazine at 2.2 kg·ha-1 and metolachlor + atrazine at 2.2 + 2.2 kg·ha-1, did not reduce root length in one study, while the remaining atrazine and metolachlor + atrazine treatments reduced cumulative root length and total root biomass 20% to 60%. Metolachlor at 2.2 kg·ha-1 reduced St. Augustinegrass root biomass by &gt;70% in one of two studies. St. Augustinegrass root elongation rate was linear or quadratic in response to all treatments. However, the rate of root elongation was similar to the untreated control for plants treated with isoxaben or oxadiazon. Chemical names used: 6-chloro-N-ethyl-N'-(l-methylethyl)-1,3,5-triazine-2,4-diamine(atrazine);S,S-dimethyl2-(difluoromethyl)-4-(2-methylpropyl)-6-(t∼fluoromethyl)-3,5-pyridinecarbothioate (dithiopyr); N-[3-(1-ethyl-1-methylpropyl)-5-isoxazolyl]-2,6-dimethoxybenzamide (isoxaben); 2-chloro-N-(2-ethyl- 6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide (metolachlor); 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin).

Elongation and Branching of Roots on Soybean Plants in a Carbon Dioxide‐Enriched Aerial Environment

AbstractPlants grown in high CO2 concentrations ([CO2]) often have a higher root weight than those grown in low [CO2]. It is usually assumed that the plants with this extra root weight can explore a greater volume of soil and will, therefore, have more water available to them. To test this assumption, soybean [Glycine max (L.) Merr. cv. Forrest] plants were grown in outdoor, sunlit plant‐growth chambers in [CO2] of 330, 450, 600, and 800 μL L−1 throughout the growing season. The soil containers in the growth chambers had a glass side and new root growth appearing at the glass was measured and marked two or three times each week. Root weight at the end of the season (93 d after emergence) was 26 to 31% higher in [CO2]‐enriched chambers compared with the 330 μL L−1 treatment, and cumulative root length was approximately proportional to [CO2]. However, CO2 treatment did not affect the rate of elongation of individual root axes. Instead, there was a significant linear increase in the number of actively growing roots with increased [CO2]. Plants grown in 800 μL L−1 had 65% more actively growing roots than plants grown in 330 μL L−1. Thus, growing a plant in high [CO2] enabled it to explore a given volume of soil more thoroughly, but did not increase the volume of soil explored.

Prediction of Kentucky Bluegrass Root Growth Using Degree‐Day Accumulation

The ability to predict the progression of turfgrass root formation would be of interest to both researchers and turfgrass practitioners. This capability would allow for improved evaluation of the effects that the timing of various management practices could have on turfgrass root production. The purpose of this study was to develop a model, based on accumulated degree‐days (ADD) calculated from soil temperature, which could predict the accumulation of ‘Baron’ Kentucky bluegrass (Poa pratensis L.) root growth during the period of January to June. Temperature at the 10 cm depth (fine quartz sand) and cumulative root length (CRL) data collected in the rhizotron facility at The Ohio State University during 1981, 1982, and 1985 were used to develop the model. Within the confined cultural and environmental conditions of this study, the model accounted for 95% of the observed variation in CRL and the actual equation was: CRL = 5.269 + 0.032(ADD) + 0.0000138(ADD2). Under field conditions, other factors besides temperature and heat unit accumulation would be expected to display strong and independent effects on turfgrass root growth. The development of a widely usable model would include provisions for variations in edaphic conditions and for the great diversity of management practices and maintenance intensity levels which are utilized today.

Sorghum root growth and water-use as affected by water supply and growth duration

Early (‘58M’) and late (‘90M’) isogenic lines of sorghum (Sorghum bicolor L. Moench) were grown in a root observation field installation at Temple, Texas in 1976, in order to study the effect of soil moisture and growth duration on root development and plant water-use. The installation consisted of soil-filled steel chambers equipped with a glass panel and installed in retaining structures in the ground. Each chamber was lifted out of the ground for weighing and measuring roots visible on the glass panel. In all chambers, soil was irrigated to field capacity prior to planting. Two soil moisture regimes were then imposed — an irrigated treatment, wherein irrigation was applied whenever soil moisture content was reduced to 50% of available soil water; and a stress treatment, wherein no irrigation was applied and plants grew on stored soil moisture. Transpiration was considerably less for the early than for the late genotype in relation to the respective leaf area of the two genotypes. Transpiration demand was met without apparent plant stress, as long as the soil moisture content of the total soil volume was greater than 20% of available soil water. Below 20% of available soil water, transpiration was controlled mainly by a reduction in leaf area through leaf senescence. Total cumulative root length per plant and root length density were larger and root length density per unit leaf area was smaller for the late than for the early genotype. Root length density per unit of green leaf area increased under conditions of soil moisture stress due mainly to the reduction in green leaf area. Root distribution along the soil profile was highly skewed (higher root concentration at shallow than at deep soil layers) with irrigation and more homogeneous without irrigation. Root growth at shallow soil layers was promoted by irrigation. Root mortality of approximately two-thirds of the total cumulative root length produced by heading was recorded. Root mortality was not only associated with total plant senescence, but with plant age and rooting depth.

Competition among the Individual Plants within a Crop : 1 Interdependence between organs in different plant types

The aim of the study was mainly to elucidate the difference in the top-root interdependence between different plant types (Erect and weep-type), from the population point of view. Materials used were Allium fistalosum L. for Erect-type and A. tuberosum Rotel for weep-type. 3 to 4 weeks after sowing, seedlings, about 10 cm in plant height, were planted in a wooden pots (25 cm × 25 cm × 25 cm) filled by the Hewitt's nutrient solution. As the treatments, 2 planting densities, 3 cm × 3 cm and 6 cm × 6 cm, and 2 nutrient levels, 1/2 and 1/5 Hewitt's solution, were employed in the experiment. Sampling was made 4 times at 2 week intervals during the experimental period after planting. Plant height, cumulative leaf blade length, maximum root length, cumulative root length, number of primary roots, top and root dry weight, and root activity were measured at every sampling occasions. As an index showing the root activity, α-Naphtylamine (α-NA) oxidizing activity in roots was ripplied. The results obtained were as follows; 1. Plant dry weight was affected more markedly by the planting density in E-type (A. fistalosum L.) over the period of experiment. In W-type (A. tuberosum Rotel), however, the nutrient level had more serious influence upon the plant growth in the latter stage of growth. 2. A high positive correlation between plant dry weight and root dry weight, cumulative root length, maximum root length were recognized in every treatment in both plant types. 3. The values of the T/R ratio in every plot was increased gradually in advance with growth in E-type (A. fistalosum L.), and was, on the contrary, decreased in W-type (A. tuberosum Rotel). 4. Calculated coefficient of allometric relative growth rate (α) was α>1 in E-type (A. fistalosum L.) and was α<1 in W-type (A. tuberosum Rotel). 5. α-NA oxidizing activity in roots decreascd in advance with growth in every treatment and it's value was higher in lower nutrient level and lower planting density.