EFFECT OF SPACING AND CLUMPING OF CORN PLANTS ON DENSITY OF CORN-ROOTWORM LARVAE (COLEOPTERA: CHRYSOMELIDAE) PER ROOT SYSTEM

1985 ◽  
Vol 117 (2) ◽  
pp. 139-142 ◽  
Author(s):  
Olga Piedrahita ◽  
C. R. Ellis ◽  
O. B. Allen
Keyword(s):  
Relative Density ◽  
Root System ◽  
Corn Rootworm ◽  
Plant Spacing ◽  
Corn Rootworms ◽  
Corn Plants ◽  
The Relationship ◽  
Field Plots

AbstractThe relative density of corn-rootworm larvae was estimated in two field plots with 4 different plant spacings and with up to 4 plants clumped per location. In both fields the relationship between plant spacing and the number of corn rootworms per sample was similar with the maximum number of larvae occurring when plants were 46 or 50 cm apart. The number of plants clumped per location affected the numbers of corn rootworm in only one field. The relationship between clumping of plants and number of corn rootworms was curvilinear in this field with the most corn rootworms occurring at 3 plants per location.

scholarly journals Response of Mexican Corn Rootworm to Insecticides, 1991

1995 ◽  
Vol 20 (1) ◽  
pp. 329-329
Author(s):  
E. Guerrero-Rodriguez ◽  
S. Davalos-Luna ◽  
J. Corrales-Reynaga
Keyword(s):  
Petri Dish ◽  
Mortality Data ◽  
Corn Rootworm ◽  
Field Corn ◽  
Paper Towel ◽  
Percent Mortality ◽  
Petri Dishes ◽  
Mexican Corn Rootworm ◽  
Corn Plants ◽  
Commercial Field

Abstract Populations of MCR of commercial field corn from Arenal, Jalisco were exposed to nine insecticides of organophosphorous (OP), cabamate, organo chlorinated and pyrethroid groups. Larvae were collected from the roots of corn plants daily, and confined in polyethylene black bags of two kg capacity with humidity and germinated corn as food for larvae. Insects were taken to the laboratory of Sanidad Vegetal in Guadalajara, Jalisco. Dilutions of the insecticides tested were prepared using acetone from 500 to 5000 ppm (6 to 9 dosage/product). For this study 20 larvae of last instar were selected and 1 u, liter of the solution was placed topically on the thorax, after this, each larva was placed in a petri dish with a moistened paper towel and the petri dishes confined in a cardboard box to eliminate light. Mortality counts were carried out at 24 hours. Percent mortality was corrected by Abbott’s formula. The mortality data were analyzed by probit to obtain LC50 and LC,5 values for each insecticide.

scholarly journals Genetic and phenotypic associations between root architecture, arbuscular mycorrhizal fungi colonisation and low phosphate tolerance instrawberry (Fragaria × ananassa)

2020 ◽  
Author(s):  
Helen Maria Cockerton ◽  
Bo Li ◽  
Eleftheria Stavridou ◽  
Abigail Johnson ◽  
Amanda Karlström ◽  
...  
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Root System ◽  
Mycorrhizal Fungi ◽  
Root Architecture ◽  
Arbuscular Mycorrhizal ◽  
System Size ◽  
Nutrient Depletion ◽  
Depletion Zone ◽  
Root System Size ◽  
The Relationship

Abstract Background: Phosphate is an essential plant macronutrient required to achieve maximum crop yield. Roots are able to uptake soil phosphate from the immediate root area, thus creating a nutrient depletion zone. Many plants are able to exploit phosphate from beyond this root nutrient depletion zone through symbiotic association with Arbuscular Mycorrhizal Fungi (AMF). Here we characterise the relationship between root architecture, AMF association and low phosphate tolerance in strawberries. The contrasting root architecture in the parental strawberry cultivars ‘Redgauntlet’ and ‘Hapil’ was studied through a mapping population of 168 progeny. Low phosphate tolerance and AMF association was quantified for each genotype to allow assessment of the phenotypic and genotypic relationships between traits. Results: A “phosphate scavenging” root phenotype where individuals exhibit a high proportion of surface lateral roots was associated with a reduction in root system size across genotypes. A genetic correlation between “root system size” traits was observed with a network of pleiotropic QTL were found to represent five “root system size” traits. By contrast, average root diameter and the distribution of roots appeared to be under two discrete methods of genetic control. A total of 18 QTL were associated with plant traits, 4 of which were associated with solidity that explained 46 % of the observed variation. Investigations into the relationship between AMF association and root architecture found that a higher root density was associated with greater AMF colonisation across genotypes. However, no phenotypic correlation or genotypic association was found between low phosphate tolerance and the propensity for AMF association, nor root architectural traits when plants are grown under optimal nutrient conditions.Conclusions: Understanding the genetic relationships underpinning phosphate capture can inform the breeding of strawberry varieties with better nutrient use efficiency. Solid root systems were associated with greater AMF colonisation. However, low P-tolerance was not phenotypically or genotypically associated with root architecture traits in strawberry plants. Furthermore, a trade-off was observed between root system size and root architecture type, highlighting the energetic costs associated with a “phosphate scavenging” root architecture.

scholarly journals FEM modeling on the compaction of Fe and Al composite powders

2015 ◽  
Vol 51 (2) ◽  
pp. 163-171 ◽  
Author(s):  
P. Han ◽  
X.Z. An ◽  
Y.X. Zhang ◽  
Z.S. Zou
Keyword(s):  
Relative Density ◽  
Flow Behavior ◽  
Compaction Pressure ◽  
Pressure Effects ◽  
Von Mises Stress ◽  
Composite Powders ◽  
Al Content ◽  
Ejection Force ◽  
Al Composite ◽  
The Relationship

The compaction process of Fe and Al composite powders subjected to single action die compaction was numerically modeled by FEM method. The relationship between the overall relative density and compaction pressure of the compacts with various Al contents was firstly identified, and the influences of Al content on the local relative density, stress, and their distributions were studied. Then the compaction pressure effects on the above properties with fixed Al content were discussed. Furthermore, detailed flow behaviors of the composite powders during compaction and the relationship between the compaction pressure and the ejection force/spring back of the compact were analyzed. The results show that: (1) With each compaction pressure, higher relative density can be realized with the increase of Al content and the relative density distribution tends to be uniform; (2) When the Al content is fixed, higher compaction pressure can lead to composite compact with higher relative density, and the equivalent Von Mises stress in the central part of the compact increases gradually; (3) Convective flow occurs at the top and bottom parts of the compact close to the die wall, each indicates a different flow behavior; (4) The larger the compaction pressure for each case, the higher the residual elasticity, and the larger the ejection force needed.

scholarly journals ROOT SYSTEM IN MAIZE PLANTS CULTIVATED UNDER WATER DEFICIT AND APPLICATION OF CHITOSAN

2020 ◽  
Vol 19 ◽  
pp. 11
Author(s):  
LORENA GABRIELA ALMEIDA ◽  
EDER MARCOS DA SILVA ◽  
PAULO CÉSAR MAGALHÃES ◽  
DÉCIO KARAM ◽  
CAROLINE OLIVEIRA DOS REIS ◽  
...  
Keyword(s):  
Plant Growth ◽  
Root System ◽  
Water Deficit ◽  
Water Availability ◽  
Agricultural Production ◽  
Negative Effects ◽  
Flowering Stage ◽  
Specific Behavior ◽  
Maize Plants ◽  
Corn Plants

Low water availability is characterized as an abiotic stressthat limits the agricultural production. Due to the physical and chemicalcharacteristics of the chitosan (CHT), this substance might stimulatephysiological responses on plants to tolerate the water deficit. In this sense,we submitted corn plants to water deficit and application of chitosan on theleaves (140 mg/L) during pre flowering stage. It were analyzed two cornhybrids genotypes contrasting for water deficit tolerance: DKB 390 (tolerant)and BRS1010 (sensitive). Then, we performed evaluations on the rootsystem and production components. Corn plants submitted to the applicationof chitosan presented a specific behavior: when compared the hybrids,the tolerant one presented a root system that was more developed and anexpressive agronomical yield. These results highlight the fact that the chitosanstimulates plant growth, enhancing their root system and contributing toincrease the availability and absorption of water and nutrients. The chitosanpresents a potential to reduce the negative effects of water deficit on the rootsystems, without compromising the agronomical yield.

scholarly journals Insect-Mediated Dispersal of the Rhizobacterium Pseudomonas chlororaphis

1998 ◽  
Vol 88 (12) ◽  
pp. 1248-1254 ◽  
Author(s):  
William E. Snyder ◽  
David W. Tonkyn ◽  
Daniel A. Kluepfel
Keyword(s):  
Escherichia Coli ◽  
Adult Stage ◽  
Genetically Modified ◽  
Insect Pest ◽  
Corn Rootworm ◽  
Transmission Route ◽  
Pseudomonas Chlororaphis ◽  
Naturally Occurring ◽  
Southern Corn Rootworm ◽  
Corn Plants

The southern corn rootworm, Diabrotica undecimpunctata subsp. howardi, a common and mobile insect pest, was shown to transmit the rhizobacte-rium Pseudomonas chlororaphis strain L11 between corn plants. Strain L11 has been genetically modified to contain the lacZY genes from Escherichia coli. It can reach high densities on roots and invade the roots and move into the foliage. D. undecimpunctata subsp. howardi became infested with L11 as larvae while feeding on roots of seed-inoculated corn and retained the bacteria through pupation, molting to the adult stage, and emergence from the soil. Bacterial densities on or in the insects increased 100-fold after they fed again as adults on L11-infested foliage. Adults retained the bacteria for at least 2 weeks after last exposure and could transmit L11 to new plants. The likelihood of transmission decreased with time since last exposure to L11, but increased with time spent on the new plants. This research demonstrates that rhizobacteria can escape the rhizosphere by moving in or onto foliage, where they can then be acquired and transmitted by insects. This transmission route may be common among naturally occurring rhizobacteria and facilitate the dispersal of both beneficial and harmful soilborne microorganisms.

Specific Gravity of Blood and Plasma at 4 and 37 °C

1974 ◽  
Vol 20 (5) ◽  
pp. 615-616 ◽  
Author(s):  
Raymond J Trudnowski ◽  
Rodolfo C Rico
Keyword(s):  
Confidence Interval ◽  
Specific Gravity ◽  
Healthy Volunteers ◽  
Relative Density ◽  
Whole Blood ◽  
Human Whole Blood ◽  
The Relationship ◽  
Density Of Water

Abstract The specific gravity (relative density) of human whole blood and plasma from 25 healthy volunteers was determined gravimetrically. For whole blood it was found to be 1.0621 (95% confidence interval: 1.0652-1.0590) at 4 °C and 1.0506 (95% confidence interval: 1.0537-1.0475) at 37 °C. Plasma specific gravity was 1.0310 (95% confidence interval: 1.0324-1.0296) at 4 °C and 1.0205 (95% confidence interval: 1.0216-1.0193) at 37 °C. All of these values are referred to the density of water at 4 °C. We show the relationship between these values and those given in the literature for measurements at 25 °C. There was a small increase in whole blood specific gravity with increasing hematocrit, but it was not statistically significant over the 40-56 hematocrit range studied.

A scheme for preliminary study of soil fertility in a district

1970 ◽  
Vol 10 (43) ◽  
pp. 196
Author(s):  
WM McArthur ◽  
K Spencer
Keyword(s):  
Soil Fertility ◽  
New South ◽  
Strong Correlations ◽  
South Wales ◽  
The Status ◽  
Using Data ◽  
Distribution Of Components ◽  
Edaphic Variables ◽  
The Relationship ◽  
Field Plots

A scheme is proposed as a basis for soil fertility studies in areas where little information is available. The first stage consists of sampling the area on a grid and determining the patterns of variation in the status of those nutrient elements likely to be deficient. These patterns are then compared with intensity patterns of environmental (including edaphic) variables. Where the two sets of variables can be quantified, regression analysis may be used to estimate the closeness of the relationship ; otherwise the relationship must be assessed visually from the degree of conformity between patterns. Those environmental variables that relate, causally or otherwise, to the distribution of components of chemical fertility are identified by strong correlations. Information so gained may be used in subsequent agronomic studies, both as a guide to number and location of field plots and as a framework for studies in soil chemistry and pedology. The scheme is illustrated using data derived from studies on the Dorrigo Plateau of New South Wales. Factors relating closely to phosphorus, sulphur, molybdenum, and nitrogen distribution were identified. In no case could one factor be used to predict the adequacy of all nutrients.

The relationship between root system development and vernalization under contrasting irrigation in bread wheat lines with the introgressions from a synthetic hexaploid

2020 ◽  
Vol 92 (3) ◽  
pp. 583-595
Author(s):  
Tatyana A. Pshenichnikova ◽  
Olga G. Smirnova ◽  
Alexander V. Simonov ◽  
Ludmila V. Shchukina ◽  
Evgeniya V. Morozova ◽  
...  
Keyword(s):  
Root System ◽  
Bread Wheat ◽  
System Development ◽  
Root System Development ◽  
Synthetic Hexaploid ◽  
Wheat Lines ◽  
The Relationship

Rearing Southern Corn Rootworms on Seedling Corn Plants

1943 ◽  
Vol 36 (2) ◽  
pp. 349-350 ◽  
Author(s):  
J. H. Bigger ◽  
R. B. March
Keyword(s):  
Corn Rootworms ◽  
Corn Plants
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