scholarly journals Movement of Indoleacetic Acid in Coleoptiles of Avena sativa L. II. Suspension of Polarity by Total Inhibition of the Basipetal Transport

1966 ◽  
Vol 41 (1) ◽  
pp. 15-27 ◽  
Author(s):  
Mary Helen M. Goldsmith
1977 ◽  
Vol 55 (12) ◽  
pp. 1641-1645 ◽  
Author(s):  
I. J. Dymock ◽  
B. Hill ◽  
A. W. Bown

Etiolated Avena sativa L. cv. Victory coleoptiles were used to determine the influence of indoleacetic acid (IAA) or malate on in vivo and in vitro rates of CO2 fixation. In addition, the influence of malate on IAA-stimulated growth was investigated. Concentrations of malate which stimulate growth did not influence the in vivo rate of dark [14C]bicarbonate fixation but did inhibit in vitro phosphoenolpyruvate carboxylase (EC 4.1.1.31) activity. IAA did not influence this enzymic activity or reduce the inhibition of the enzyme by malate, and the rate of [14C]bicarbonate fixation was not measurably influenced by 20 μM IAA within the time period required for IAA stimulation of growth to become apparent. In the absence of atmospheric levels of CO2, 1 mM malate and 20 μM IAA stimulate growth in a weakly synergistic manner. These results are discussed in relationship to a suggestion that IAA-stimulated H+ secretion and growth involves a rapid effect on CO2 fixation.


Planta ◽  
1977 ◽  
Vol 135 (2) ◽  
pp. 149-154 ◽  
Author(s):  
Elisabeth Tietze-Ha� ◽  
Karl D�rffling

Author(s):  
B. K. Kirchoff ◽  
L.F. Allard ◽  
W.C. Bigelow

In attempting to use the SEM to investigate the transition from the vegetative to the floral state in oat (Avena sativa L.) it was discovered that the procedures of fixation and critical point drying (CPD), and fresh tissue examination of the specimens gave unsatisfactory results. In most cases, by using these techniques, cells of the tissue were collapsed or otherwise visibly distorted. Figure 1 shows the results of fixation with 4.5% formaldehyde-gluteraldehyde followed by CPD. Almost all cellular detail has been obscured by the resulting shrinkage distortions. The larger cracks seen on the left of the picture may be due to dissection damage, rather than CPD. The results of observation of fresh tissue are seen in Fig. 2. Although there is a substantial improvement over CPD, some cell collapse still occurs.Due to these difficulties, it was decided to experiment with cold stage techniques. The specimens to be observed were dissected out and attached to the sample stub using a carbon based conductive paint in acetone.


Author(s):  
H.M. Mazzone ◽  
G. Wray ◽  
R. Zerillo

The fungal pathogen of the Dutch elm disease (DED), Ceratocystis ulmi (Buisman) C. Moreau, has eluded effective control since its introduction in the United States more than sixty years ago. Our studies on DED include establishing biological control agents against C. ulmi. In this report we describe the inhibitory action of the antibiotic polymyxin B on the causal agent of DED.In screening a number of antibiotics against C. ulmi, we observed that filter paper discs containing 300 units (U) of polymyxin B (Difco Laboratories) per disc, produced zones of inhibition to the fungus grown on potato dextrose agar or Sabouraud agar plates (100mm x 15mm), Fig. 1a. Total inhibition of fungal growth on a plate occurred when agar overlays containing fungus and antibiotic (polymyxin B sulfate, ICN Pharmaceuticals, Inc.) were poured on the underlying agar growth medium. The agar overlays consisted of the following: 4.5 ml of 0.7% agar, 0.5 ml of fungus (control plate); 4.0 ml of 0.7% agar, 0.5 ml of fungus, 0.5 ml of polymyxin B sulfate (77,700 U). Fig. 1, b and c, compares a control plate and polymyxin plate after seven days.


Planta Medica ◽  
2013 ◽  
Vol 79 (10) ◽  
Author(s):  
S Chon ◽  
R Earland ◽  
A Pappas ◽  
KA Reynertson ◽  
MD Southall

Author(s):  
Francisco Gavi Reyes ◽  
César Botello-Aguillón ◽  
Leonardo Tijerina-Chávez ◽  
Arturo Galvis-Spíndola ◽  
Rodrigo Roblero-Hidalgo

E Objetivo: Desarrollar un procedimiento para estimar biomasa con imágenes digitales captadas desde un dron y modelación 3D (ID-Dron-3D) aplicable en alfalfa (Medicago sativa L.) y avena forrajera (Avena sativa L.). Diseño/metodología/aproximación: Con una cámara digital acoplada al dron se obtuvieron imágenes antes de la cosecha de los cultivos, que fueron procesadas con software para luego estimar volumen de biomasa. En cada cultivo se midió altura de la planta y área cosechada, volumen aparente y real de biomasa, y peso de biomasa fresca y seca. Resultados: Con base en el análisis de regresión se obtuvieron modelos lineales a una p<0.05 para predecir: biomasa fresca en avena (R2=0.70) y alfalfa (R2 =0.47); y biomasa seca en avena (R2=0.78) y en alfalfa (R2=0.31) mediante ID-Dron-3D. Limitaciones del estudio/implicaciones: Considerando las R2 de los modelos obtenidos, los resultados en la avena forrajera fueron mejores, respecto a los detectados en alfalfa, lo cual se puede deber a la mayor variabilidad de la cobertura vegetal, ya que, en algunas unidades de muestreo, las plantas de alfalfa no cubrían completamente el suelo. Hallazgos/conclusiones: El rendimiento de biomasa fresca y seca de ambos cultivos se correlacionó significativamente con su respectivo volumen aparente estimado con imágenes digitales tomadas desde un dron y su procesamiento 3D (ID-Dron-3D).


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