Disappearance of IAA in the presence of tissues of sunflowers infected by Plasmopara halstedii

1974 ◽  
Vol 52 (4) ◽  
pp. 861-866 ◽  
Author(s):  
Yigal Cohen ◽  
W. E. Sackston
Keyword(s):  
Indoleacetic Acid ◽  
Stem Elongation ◽  
Plasmopara Halstedii ◽  
Positive Correlation ◽  
Leaf Stage ◽  
Apical Buds ◽  
Leaf Tissues ◽  
Highly Correlated ◽  
Stem Slices

Stem elongation of sunflower plants inoculated at the two-leaf stage through apical buds with Plasmopara halstedii was greatly inhibited. Systemically infected plants did not show normal phototropic and negative-geotropic responses. There was a positive correlation between stunting of infected plants and ability of stem slices to remove indoleacetic acid (IAA) from test solutions. IAA disappearance in the presence of stem slices of infected plants was also highly correlated with area of mildew symptoms on leaves. Although IAA disappeared in the presence of all diseased tissues, leaf tissues were least active. No IAA disappeared in the presence of sporangia of the pathogen. These results explain reduced levels of IAA observed in mildew-infected sunflowers in earlier studies and may account for the characteristic stunting of systemically infected plants.

Factors affecting infection of sunflowers by Plasmopara halstedii

1973 ◽  
Vol 51 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Yigal Cohen ◽  
W. E. Sackston
Keyword(s):  
Systemic Infection ◽  
Optimum Temperature ◽  
Plasmopara Halstedii ◽  
Factors Affecting ◽  
Leaf Stage ◽  
Apical Bud ◽  
Apical Buds ◽  
Local Lesions ◽  
Young Leaves ◽  
Incubation Temperatures

Systemic infection of sunflowers by Plasmopara halstedii occurs much more readily through hypocotyls than through roots, and through apical buds than through leaves.Systemic symptoms rarely develop from belowground infections of plants past the four-leaf stage, and from apical bud infections of plants past the eight-leaf stage. Necrotic lesions may occur and the pathogen may sporulate on hypocotyls and roots of plants with no typical systemic symptoms.Infection by sporangia produces local lesions in young leaves; some of these infections may become systemic.Immersion of 3-day-old seedlings in inoculum for 1 min resulted in some infection; highest infection resulted from 3- to 6-h exposure.Systemic infection resulted from apical bud inoculation with suspensions averaging one sporangium per plant.Optimum temperature during inoculation of 3-day-old seedlings was 15°, and during incubation was 20° to 25 °C. Optimum temperature during bud inoculation was 15°; incubation temperatures from 15° to 25 °C gave essentially similar results.

Seed and herbage production of Westerwolds ryegrass as influenced by applied nitrogen

2004 ◽  
Vol 84 (3) ◽  
pp. 791-793 ◽  
Author(s):  
H. T. Kunelius ◽  
K. B. McRae ◽  
G. H. Dürr ◽  
S. A. E. Fillmore
Keyword(s):  
Seed Yield ◽  
Nitrogen Fertilizer ◽  
Crude Protein ◽  
Stem Elongation ◽  
Lolium Multiflorum ◽  
Production Plant ◽  
Leaf Stage ◽  
Acid Detergent Fibre ◽  
Plant Characteristics ◽  
Seed Yields

Seed production, plant characteristics and herbage regrowth of three cultivars of Westerwolds ryegrass (Lolium multiflorum Lam.) were determined during 3 production years. Ryegrass was fertilized with nitrogen at 60, 90 and 120 kg ha-1 applied either all at the two- to three-leaf stage or split (3:2) between the two- to three-leaf stage and stem elongation. Seed yield of three cultivars ranged from 742 to 1440 kg ha-1. Nitrogen fertilizer at 90 kg ha-1 resulted in near maximum seed yields. Single and split applications of nitrogen resulted in similar seed yields. Density of fertile tillers ranged from 541 to 911 m-2 among the cultivars and responded linearly to applied N. A positive relationship was detected between the density of fertile tillers and seed yield. Herbage in aftermath averaged 2280 kg ha-1 dry matter, 125 g kg-1 crude protein, 597 g kg-1 neutral detergent fibre and 344 g kg-1 acid detergent fibre. Key words: Lolium multiflorum, Westerwolds ryegrass, nitrogen fertilizer, seed, tiller, spikelet, herbage, herbage composition

scholarly journals The competitive ability of Chenopodium album and Echinochloa crus-galli in maize crops depending on the time of their occurrence or removal

2016 ◽  
Vol 69 (4) ◽  
Author(s):  
Hanna Golebiowska ◽  
Renata Kieloch
Keyword(s):  
Competitive Ability ◽  
Stem Elongation ◽  
Chenopodium Album ◽  
Weed Competition ◽  
Growth Stages ◽  
Competitive Effect ◽  
Leaf Stage ◽  
Weed Infestation ◽  
Small Plot ◽  
Weed Emergence

Small-plot experiments for two levels of infestation (20 and 40 plants per m<sup>2</sup>) with <em>Chenopodium album</em> L. and <em>Echinochloa crus-galli</em> (L.) P. Beav were conducted in the 2009–2011 seasons. In the first variant, the effect of time of weed removal on maize was investigated. Weeds were removed in the following growth stages of maize: one, three, five, and seven leaves, the beginning of stem elongation, and the stage from the fourth to sixth node. The second variant concerned the effect of time of weed emergence on maize and included the same maize growth stages as mentioned above. In both treatments, weed competition was compared to the control – the plot completely free from weeds, as well as to the plot fully covered with weeds. <em>Echinochloa crus-galli</em> in the amount of 20 plants per m<sup>2</sup>, which were not removed until the five-leaf stage or which emerged immediately after the seven-leaf stage of maize, did not show any competitive effect on the growth and development of maize. <em>Chenopodium album</em> was characterized by a similar effect at the same level of weed infestation severity and when not removed until the five-leaf stage as well as in the case of plants that emerged after the seven-leaf stage of maize. Both species present in an amount of 40 plants per m<sup>2</sup> needed to be removed no later than at the three-leaf stage of maize.

scholarly journals Characterization of Spinach Germplasm for Resistance Against Two Races of Verticillium dahliae

HortScience ◽  
2015 ◽  
Vol 50 (11) ◽  
pp. 1631-1635 ◽  
Author(s):  
Beiquan Mou ◽  
Steven J. Klosterman ◽  
Amy Anchieta ◽  
Elisabeth Wood ◽  
Krishna V. Subbarao
Keyword(s):  
Verticillium Dahliae ◽  
Stem Elongation ◽  
Disease Incidence ◽  
Quantitative Polymerase Chain Reaction ◽  
Germplasm Collection ◽  
Seed Transmission ◽  
Sources Of Resistance ◽  
Department Of Agriculture ◽  
Race 2 ◽  
Highly Correlated

Historically, wilt disease caused by Verticillium dahliae has not presented a problem in California spinach production because the crop is harvested well before the symptoms develop after the stem elongation (bolting) stage. However, infested spinach seeds introduce or increase inoculum in the soil for rotational crops such as lettuce. This investigation was designed to identify verticillium wilt-resistant accessions in the U.S. Department of Agriculture (USDA) spinach germplasm collection against races 1 and 2 of V. dahliae, and to examine seed transmission of the pathogen in different spinach genotypes. In a seed health assay of 392 accessions, 21(5.4%) were positive for V. dahliae, and 153 (39%) were positive for Verticillium isaacii. A total of 268 accessions plus nine commercial cultivars were then screened against one race 1 and two race 2 isolates from spinach in replicated greenhouse experiments. Disease incidence, severity, and seed transmission through plating on NP-10 medium and real-time quantitative polymerase chain reaction (qPCR) were assessed. There was wide variation among accessions in their response to V. dahliae with disease incidence ranging from 0% to 100%. The two race 2 isolates differed in their virulence against spinach genotypes. Resistant accessions were identified against both races 1 and 2. Recovery of V. dahliae from seeds plated on NP-10 medium and qPCR results were highly correlated (P = 0.00014). Some accessions identified as resistant based on disease incidence showed little seed transmission of the pathogen. Even though lower wilt incidence and severity generally corresponded with lower seed transmission rates, there were exceptions (r = 0.52). Variation among plants within accessions was also observed. Nevertheless, the sources of resistance identified in this study are useful for spinach cultivar improvement.

Relationship between arterial oxygen desaturation and ventilation during maximal exercise

1992 ◽  
Vol 73 (6) ◽  
pp. 2588-2591 ◽  
Author(s):  
M. Miyachi ◽  
I. Tabata
Keyword(s):  
Maximal Exercise ◽  
Arterial Oxygen ◽  
Distance Runners ◽  
Long Distance ◽  
Positive Correlation ◽  
Ventilatory Equivalent ◽  
Wide Range ◽  
Highly Correlated ◽  
End Tidal ◽  
Arterial O2 Saturation

The purpose of the present study was to investigate the contribution of ventilation to arterial O2 desaturation during maximal exercise. Nine untrained subjects and 22 trained long-distance runners [age 18–36 yr, maximal O2 uptake (VO2max) 48–74 ml.min-1 x kg-1] volunteered to participate in the study. The subjects performed an incremental exhaustive cycle ergometry test at 70 rpm of pedaling frequency, during which arterial O2 saturation (SaO2) and ventilatory data were collected every minute. SaO2 was estimated with a pulse oximeter. A significant positive correlation was found between SaO2 and end-tidal PO2 (PETO2; r = 0.72, r2 = 0.52, P < 0.001) during maximal exercise. These statistical results suggest that approximately 50% of the variability of SaO2 can be accounted for by differences in PETO2, which reflects alveolar PO2. Furthermore, PETO2 was highly correlated with the ventilatory equivalent for O2 (VE/VO2; r = 0.91, P < 0.001), which indicates that PETO2 could be the result of ventilation stimulated by maximal exercise. Finally, SaO2 was positively related to VE/VO2 during maximal exercise (r = 0.74, r2 = 0.55, P < 0.001). Therefore, one-half of the arterial O2 desaturation occurring during maximal exercise may be explained by less hyperventilation, specifically for our subjects, who demonstrated a wide range of trained states. Furthermore, we found an indirect positive correlation between SaO2 and ventilatory response to CO2 at rest (r = 0.45, P < 0.05), which was mediated by ventilation during maximal exercise. These data also suggest that ventilation is an important factor for arterial O2 desaturation during maximal exercise.

Proximal fluorescence sensing for in-season diagnosis of rice nitrogen status

2017 ◽  
Vol 8 (2) ◽  
pp. 343-348 ◽  
Author(s):  
S. Huang ◽  
Y. Miao ◽  
F. Yuan ◽  
Q. Cao ◽  
H. Ye ◽  
...  
Keyword(s):  
Stem Elongation ◽  
N Uptake ◽  
Growth Stages ◽  
Fluorescence Sensing ◽  
N Nutrition ◽  
N Concentration ◽  
Field Samples ◽  
Highly Correlated ◽  
Different Growth Stages ◽  
N Status

The objective of this study was to evaluate the potential of using Multiplex 3, a hand-held canopy fluorescence sensor, to determine rice nitrogen (N) status at different growth stages. In 2013, a paddy rice field experiment with five N fertilizer treatments and two varieties was conducted in Northeast China. Field samples and fluorescence data were collected simultaneously at the panicle initiation (PI), stem elongation (SE), and heading (HE) stages. Four N status indicators, leaf N concentration (LNC), plant N concentration (PNC), plant N uptake (PNU) and N nutrition index (NNI), were determined. The preliminary results indicated that different N application rates significantly affected most of the fluorescence variables, especially the simple fluorescence ratios (SFR_G, SFR_R), flavonoid (FLAV), and N balance indices (NBI_G, NBI_R). These variables were highly correlated with N status indicators. More studies are needed to further evaluate the accuracy of rice N status diagnosis using fluorescence sensing at different growth stages.

scholarly journals Goodness and Accentedness Ratings of /hVt/ Tokens by Aware and Naive Listeners

2016 ◽  
Vol 25 (4) ◽  
pp. 620-633
Author(s):  
Amber D. Franklin ◽  
Kara A. Oksanen ◽  
Kaitlyn E. Gilfert
Keyword(s):  
Decision Making ◽  
Native Language ◽  
Likert Scale ◽  
High Positive Correlation ◽  
Positive Correlation ◽  
Listener Responses ◽  
Japanese Speakers ◽  
Highly Correlated ◽  
Decision Making Criteria

Purpose This study compares goodness and accentedness ratings of speech tokens rated by listeners who are naive to and aware of speakers' native language backgrounds. Listener responses to open-ended questions regarding goodness and accentedness ratings are also examined. Method Twenty-eight monolingual speakers of U.S. English served as listeners. Listeners were presented with 5 blocks of /hVt/ tokens. Each block represented a different vowel target and comprised correct and incorrect productions from English, Spanish, Korean, and Japanese speakers. Listeners rated goodness and accentedness using a 9-point Likert scale and explained their decision-making criteria when judging goodness versus accentedness. Results There is a high positive correlation between goodness and accentedness. Both naive and aware listeners assigned poorer ratings when judging goodness compared with accentedness, but results varied on the basis of target accuracy. Aware listeners assigned better goodness and accentedness ratings compared with naive listeners. This difference was highly statistically significant. Both accentedness and goodness ratings are susceptible to listener bias. Conclusions Goodness and accentedness are highly correlated yet distinct measures. Goodness is more reflective of target accuracy than is accentedness. Native English tokens were affected by listener bias to a greater extent than nonnative English tokens.

Morphological and Histological Effects of Three Grass Selective Herbicides on Developing Wild Oat (Avena fatua) Stems

Weed Science ◽  
1989 ◽  
Vol 37 (4) ◽  
pp. 575-584 ◽  
Author(s):  
Rakesh Jain ◽  
William H. Vanden Born
Keyword(s):  
Cell Division ◽  
Histological Examination ◽  
Cell Elongation ◽  
Stem Elongation ◽  
Avena Fatua ◽  
Wild Oat ◽  
Stem Tissue ◽  
Leaf Stage ◽  
Initial Injury ◽  
Observation Times

Three grass selective herbicides, sethoxydim, fluazifop, and haloxyfop, applied to wild oat plants at the five-leaf stage inhibited growth and induced chlorosis in leaves. Young and actively growing tissues were affected first. Stem elongation in wild oat was inhibited within 2 days of treatment with sethoxydim and within 5 days of treatment with fluazifop or haloxyfop. At these same observation times, internodes that were elongating rapidly at the time of treatment were constricted at the base. These symptoms were followed by necrosis of the internode tissue. Histological examination of the affected internodes indicated that the herbicides inhibited cell division in very young internodes and inhibited both cell division and cell elongation in slightly older internodes. Initial injury occurred in the epidermal, cortical, and procambium cells of the peripheral regions of the stems located at the base of the affected internodes. Necrosis then progressed to the center of the stem tissue and all cells in the internodes were killed within 14 days of treatment. All three herbicides caused similar morphological and histological effects on developing wild oat stems.

scholarly journals Changes in the Cellular Concentrations of Elements in Tobacco Leaf Tissues during Growth and Senescence

1989 ◽  
Vol 14 (5) ◽  
pp. 297-312
Author(s):  
P Echlin
Keyword(s):  
Leaf Tissue ◽  
Mesophyll Cells ◽  
Spongy Mesophyll ◽  
X Ray ◽  
Positive Correlation ◽  
Stages Of Growth ◽  
Sodium Magnesium ◽  
Leaf Tissues ◽  
Phosphorus And Potassium ◽  
Late Stages

AbstractQuantitative X-ray microanalysis for nine elements has been carried out on frozen, fully hydrated fracture faces of upper and lower epidermis, palisade and spongy mesophyll cells in leaf tissue of Nicotianatabacum L. cv. Coker 319 taken from plants at five different stages of growth. Although concentrations of aluminium, silicon and chlorine generally fell below the minimum-detection limit, the values for sodium, magnesium, phosphorus, sulphur, potassium and calcium were consistently higher and showed differences among tissue types and stages of growth. The general trend was for elemental concentrations to increase up to the mature and ripe stages of growth and then to decrease as the leaf ages further. The sodium values were highest at the beginning and end of the five stages of growth, with higher amounts in the epidermal tissues. As the leaves age, the levels of magnesium fell in the photosynthetic tissues but increased in the epidermal tissues. Such changes could be correlated with higher concentrations of potassium at the early stages of growth and with much lower values at the late stages. The sulphur levels showed only small differences between tissue types at all stages of growth. The calcium levels increased with age and there were consistently higher concentrations in the photosynthetic tissues than in the two epidermal layers. The levels of phosphorus were low in all tissue types and decreased with age. There is an increasing positive correlation between phosphorus and magnesium and a decreasing positive correlation between phosphorus and potassium during growth and senescence.

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