scholarly journals Effects of Soil Pasteurization, Fungicide Application, and Temperature on Mycorrhizal Development and Plant Growth : Interim Report

1982 ◽  
Author(s):  
Stephen Verkade ◽  
David Hamilton
Keyword(s):  
Plant Growth ◽  
Interim Report ◽  
Fungicide Application ◽  
Mycorrhizal Development ◽  
Soil Pasteurization

Evaluation of winter wheat management practices under semi-arid conditions

1992 ◽  
Vol 72 (1) ◽  
pp. 1-12 ◽  
Author(s):  
G. P. Lafond
Keyword(s):  
Plant Growth ◽  
Winter Wheat ◽  
Nitrogen Fertilizer ◽  
Growing Season ◽  
Late Season ◽  
Fungicide Application ◽  
Residual Nitrogen ◽  
Growing Conditions ◽  
Semi Arid ◽  
Growing Season Precipitation

A study was conducted to evaluate European cereal management techniques in winter wheat under semi-arid growing conditions. Combinations of rates and split applications of ammonium nitrate fertilizer with a plant growth regulator and/or a late season fungicide application were investigated using no-till "stubbled-in" production practices in two winter wheat cultivars, Norwin and Norstar at two locations over 3 yr. Nitrogen fertilizer gave the maximum yield when it was applied in mid-April. Split applications of nitrogen did not improve grain yields or grain protein concentration. A height reduction was observed with the use of plant growth regulators in both cultivars but no benefits were incurred due to the lack of lodging. The late season fungicide application had some effect on increasing kernel weight in both cultivars but rarely translated into a higher yield. Nitrogen and growing conditions had the largest effects on yield and the dilemma faced by producers is to correctly match nitrogen rates with environmental conditions given that the nitrogen has to be applied early in the spring. Available spring soil moisture and soil residual nitrogen provided little help in determining the rate of nitrogen giving the maximum economic yield because assumptions on growing season precipitation have to be made. It is suggested that nitrogen management be based on a risk analysis which would involve determining the probability of different levels of growing season precipitation for various climatic zones and soil types and the corresponding yield levels expected. Rates of nitrogen fertilizer would then be adjusted according to soil residual nitrogen levels and the risk the producer is willing to assume. This will require more extensive research and development of crop production models.Key words: Nitrogen fertilizer, Triticum aestivum L., intensive cereal management, propiconazole, chlormequat chloride, ethephon

Effect of selected insecticides on plant growth and mycorrhizal development in sorghum

1993 ◽  
Vol 43 (3-4) ◽  
pp. 337-343 ◽  
Author(s):  
J. Veeraswamy ◽  
T. Padmavathi ◽  
K. Venkateswarlu
Keyword(s):  
Plant Growth ◽  
Mycorrhizal Development

scholarly journals A Simulation Model for Epidemics of Stem Rust in Ryegrass Seed Crops

2015 ◽  
Vol 105 (1) ◽  
pp. 45-56 ◽  
Author(s):  
W. F. Pfender ◽  
D. Upper
Keyword(s):  
Plant Growth ◽  
Simulation Model ◽  
Disease Severity ◽  
Stem Rust ◽  
Infectious Period ◽  
Calibration Data ◽  
Disease Cycle ◽  
Fungicide Application ◽  
Action Threshold ◽  
Seed Crops

A simulation model (STEMRUST_G, named for stem rust of grasses) was created for stem rust (caused by Puccinia graminis subsp. graminicola) in perennial ryegrass grown to maturity as a seed crop. The model has a daily time step and is driven by weather data and an initial input of disease severity from field observation. Key aspects of plant growth are modeled. Disease severity is modeled as rust population growth, where individuals are pathogen colonies (pustules) grouped in cohorts defined by date of initiation and plant part infected. Infections due to either aerial spread or within-plant contact spread are modeled. Pathogen cohorts progress through life stages that are modeled as disease cycle components (colony establishment, latent period, infectious period, and sporulation) affected by daily weather variables, plant growth, and fungicide application. Fungicide effects on disease cycle components are modeled for two commonly used active ingredients, applied preinfection or postinfection. Previously validated submodels for certain disease cycle components formed the framework for integrating additional processes, and the complete model was calibrated with field data from 10 stem rust epidemics. Discrepancies between modeled outcomes and the calibration data (log10[modeled] − log10[observed]) had a mean near zero but considerable variance, with 1 standard deviation = 0.5 log10 units (3.2-fold). It appears that a large proportion of the modeling error variance may be due to variability in field observations of disease severity. An action threshold for fungicide application was derived empirically, using a constructed weather input file favorable for disease development. The action threshold is a negative threshold, representing a level of disease (latent plus visible) below which damaging levels of disease are unable to develop before the yield-critical crop stage. The model is in the public domain and available on the Internet.

The effect of inoculation of cashew with NutriLink on vesicular arbuscular mycorrhizal infection and plant growth

1993 ◽  
Vol 44 (6) ◽  
pp. 1211 ◽  
Author(s):  
LM Haugen ◽  
SE Smith
Keyword(s):  
Plant Growth ◽  
Glomus Intraradices ◽  
Arbuscular Mycorrhizal ◽  
Nutrient Concentrations ◽  
Triple Superphosphate ◽  
Mycorrhizal Infection ◽  
Positive Effects ◽  
Negative Effect ◽  
Potential Benefits ◽  
Mycorrhizal Development

This investigation was initiated to assess whether inoculation of cashew (Anacardium occidentale) seedlings under commercial nursery conditions would result in mycorrhizal development in the root systems and increased growth of the plants. Three experiments were carried out to investigate the effects of different nursery factors on infection and plant growth. These were: use of triple superphosphate, pH of the potting mix (varied by lime additions) and removal of the cotyledons. Inoculation with the commercially available mycorrhizal inoculum Nutrilink� (containing spores of Glomus intraradices) resulted in mycorrhiza formation, but the levels of infection were low even in the absence of triple superphosphate addition. The highest infection (55%) was observed in seedlings from which the cotyledons had been removed. Inoculated plants in general grew less well than non-inoculated plants under all conditions. This depression may be the result of changes in pH following inoculation or the result of development of mycorrhizal infection. There were no positive effects of inoculation on nutrient concentrations in the tissues, except that inoculated plants had higher concentrations of K in both leaves and roots. Addition of lime to the potting mix did not significantly affect the extent of infection or the responses of the plants. Cotyledon removal was associated with higher infection and a reduction in the negative effect of inoculation on growth, although plant growth was reduced in inoculated and non-inoculated treatments. It does not appear that inoculation with NutriLink is appropriate in the potting mixes used, particularly as the formulation causes changes in pH of the potting mixes. Other strategies will need to be adopted to optimize potential benefits of mycorrhizas in cashew production.

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