Variation In Root Length Research Articles

ROOT ELONGATION IN VARIOUS AGRONOMIC CROPS BY THE PLANT GROWTH PROMOTING RHIZOBACTERIUM PSEUDOMONAS PUTIDA GR12–2

Seeds of canola, lettuce, tomato, barley, wheat, and oats were inoculated with either the wild-type plant growth promoting rhizobacterium (PGPR),Pseudomonas putidaGR12–2, or the mutantP. putidaGR 12–2lacd68 (deficient in the activity of the enzyme 1-aminocyclopropane-1-carboxylate deaminase) alone and in conjunction with either an inhibitor of ethylene biosynthesis, L-α-(aminoethoxyvinyl)-glycine (AVG), or the chemical ethylene generator, (2-chloroethyl) phosphonic acid (ethophon). For the different treatments, variations in root length under gnotobiotic conditions were compared. Canola, lettuce, tomato, and wheat responded to all of the treatments in a similar manner: The root lengths increased when seeds were treated withP. putidaGR 12–2 and/or AVG but not with the mutant strain, in comparison with a MgSO4control treatment, while the ethophon treatment inhibited root elongation. With barley and oat, none of the treatments had any effect on root lengths; however, when the ethophon concentration was increased, root elongation of these two plants was also inhibited. These observations are consistent with a model in which promotion of root growth byP. putidaGR 12–2 is a consequence of inhibition of ethylene production within the developing seedling.

Cataracts, radiculomegaly, septal heart defects and hearing loss in two unrelated adult females with normal intelligence and similar facial appearance: confirmation of a syndrome?

Two unrelated, adult females with normal intelligence are described. They show a similar clinical picture with a long and narrow face, congenital cataract, microphthalmia, microcornea, a high nasal bridge, a short nose, a broad nasal tip, a long philtrum, bilateral hearing loss, persistent primary teeth, oligodontia, variable root length including dental radiculomegaly, heart defects and cutaneous syndactyly of the 2nd-3rd toes. Abnormalities present in only one of the two patients were a cleft palate and a transverse vaginal septum, respectively. There are numerous similarities between our two patients and the family described by Wilkie et al. ((1993): Clin Dysmorphol 2: 114-119) and all may be examples of the same entity.

Distribution of grapevine roots and salt under drip and full-ground cover microjet irrigation systems

We describe the three dimensional variation in root length density (Lv) within a quarter of the planting area of Colombard grapevines on Ramsey rootstock grown under drip and full-cover microjet irrigation. Under drip irrigation roots were concentrated under the vine row, whereas under microjet irrigation roots were evenly spread across the planting area. The maximum Lv were 1.2 and 0.6 cm/cm3 and the estimated total root lengths per vine were 32 and 26 km for drip and microjet irrigated vines, respectively. Under drip irrigation, 56% of the variation in Lv could be accounted for as a function of depth and radial distance into the row, and under microjet, 45% of the variation in Lv could be accounted for as a function of depth. Twenty five per cent of the vine roots were in soil with an air filled porosity at field capacity of 6% or less. Based on the variation of root length per unit area (La) across a quarter of the planting area and between vines, we concluded that selection of a location at which the La would be representative of that in the entire irrigation unit is feasible in microjet irrigated vines but not in those irrigated with drip. The absence of a location representative of La confounds the scheduling of drip irrigation based solely on measurements of soil moisture.

An Irrigation Scheduling Model for Turnip Greens

An irrigation scheduling model for turnip (Brassica rapa L.) was validated using a line-source irrigation system in a 2-year field trial. The model used a water balance, a variable root length, and a crop factor function of plant age (i). Evapotranspiration was computed daily as class A pan evaporation times a crop factor [CF(i) = 0.365 + 0.0154i-0.00011i2]. Irrigation according to the model maintained soil water tension at <25 kPa at a 30-cm depth. When rainfall amounts were less than water use, leaf yields responded quadratically to irrigation rates, from 0% to 160% of the model rate, and the highest leaf yield with the lowest water applications corresponded to the model rate. Therefore, this model could replace the “feel or see” methods commonly used for scheduling irrigation of leafy vegetables grown in the southeastern United States.

A diallel analysis of seedling growth in cotton

The relationships among seedling measurements and the inheritance of seedling growth of cotton, Gossypium hirsutum L., in a controlled environment were studied using a diallel cross of eight parents. The parents included six strains from the Multi-Adversity Resistance (MAR) program and two commercial cultivars. Variation in root length on the fourth day after planting did not vary among the parents. The MAR strains generally had slower root elongation, measured by root length on day 9, than did the two cultivars. Variation in velocity of emergence indicated some parents established longer roots before emergence than did other parents. Variation in hypocotyl length on days 10 and 18 reflected differences in emergence speed. The rate of hypocotyl elongation, measured as the difference between day 10 and day 18 hypocotyl lengths, was similar for all parents. The parental and offspring data showed similar trends for velocity of emergence, day 9 root length and day 18 hypocotyl length. Offspring of parents which had extreme values for the traits expressed approximately mid-parent values. The offspring of parents which had similar values frequently were heterotic. However, the direction of heterosis shown by offspring of parents having high values was opposite to that shown by offspring of parents having low values. An explanation involving duplicate gene action and epistasis is proposed.

Genetic Variability in Root and Shoot Growth Characteristics of Peanut1,2

Abstract The shape and extent of root systems influence the rate and pattern of nutrient and water uptake from the soil. In dicotyledons such as peanut (Arachis hypogaea L.), the primary root and its laterals constitute the main root system. Rooting trait differences in some crops have been associated with drought tolerance. Our objective in this study was to determine if variation in root length and number occurs among peanut genotypes. In one test, shoot and root growth of 23 genotypes (12 spanish and 11 virginia types) were compared in the greenhouse at 55 days after planting using clear acrylic tubes 7.5 cm in diameter and 2.2 m in length. Shoot dry weight, leaf area, tap root length, and root number at 1 m depth ranged for spanish-type entries from 1.23 to 2.65 g, 214 to 409 cm2, 95.0 to 186.8 cm, and 1.0 to 3.1, respectively. Similarly, ranges for virginia-type entries were 1.35 to 3.23 g, 135 to 460 cm2, 122.4 to 192.6 cm, and 1.0 to 7.1. Correlations between shoot and root parameters indicated strong positive association between aerial and subterranean growth. However, the relationship of leaf area to root length was stronger for virginia- than for spanish-type entries. Root length and numbers were highly correlated for spanish, but not for virginia entries. In other tests that included two each of virginia-, spanish-, and valencia-type entries, similar results were found for plants at 34 and 47 days after planting. Significant differences in both root (length and numbers) and shoot growth (dry weight and leaf area) were found among the genotypes tested. Inherent differences in root growth rate were evident at early stages of seedling growth. The results from this sample of peanut germplasm indicate that there is considerable diversity in root growth and there is high shoot/root growth association.

Selection for ryegrass genotypes with tolerance to aluminum toxicity

Abstract This study reports on a procedure where ryegrass (Lolium multiflorum Lam.) varieties are screened for tolerance to aluminum toxicity. The procedure utilized was a solution‐paper method where seedlings were grown on filter paper which transported nutrient solution from a reservoir. Mean root length for genotypes was the character utilized to determine tolerance to aluminum toxicity. Ryegrass genotypes were subjected to [Al] between 0 to 8 mM with the most useful concenrations being from 2 to 4 mM. Genotypes which demonstrated some tolerance to higher [Al] were North American Plant Breeders R. 0051, ‘Aubade’, ‘Urbana’, Fla 1977B, ‘Tetragulf, Mommersteeg Lmw 96. Considerable variation in root length due to genotypic effect tended to obscure the [Al] effect. The relative rankings of root growth ratios of 4 mM [Al] to 2 mM [Al] tolerance of ryegrass cultivars is questionable. Further work to establish a more reliable screening technique for this specie needs to be undertaken.

The effect of irrigation on the length, weight, and diameter of lettuce roots

The total fibrous-root length of mature field-grown lettuces, which were protected from rainfall and not irrigated after establishment was less than 75 per cent of that of irrigated plants, although the corresponding root weights were very similar. Non-irrigated plants had thicker roots, less roots near the soil surface, and more at depth. Up to the time that the roots started to die, about two weeks before the lettuce were mature, the variation of root length with depth and time is described by a simple logarithmic expression. re]19730803

Variation in root length of the permanent maxillary central incisor.

abstract— A metric study was performed on radiographs of permanent maxillary central incisors of a normal Swedish population of 1,038 children. The normal distribution of the root lengths revealed two extreme groups: 2.4% had short roots, formerly described as Short Root anomaly, most prevalent among girls with a boy:girl ratio of 1:2.6. In the opposite extreme group, i.e., with exceptionally long roots comprising 2.3% of the children, the boys dominate with a boy:girl ratio of 5:1. Clinical evidence suggests that variation in root length is of genetic origin.