Effects of diurnal temperature fluctuations on population responses of forest floor mites

Pedobiologia ◽  
2003 ◽  
Vol 47 (4) ◽  
pp. 331-339 ◽  
Author(s):  
Alexei V. Uvarov
Plant Disease ◽  
2020 ◽  
Vol 104 (11) ◽  
pp. 2891-2897
Author(s):  
Pippa J. Michael ◽  
King Yin Lui ◽  
Linda L. Thomson ◽  
Katia Stefanova ◽  
Sarita J. Bennett

Sclerotinia stem rot, caused by the necrotrophic plant pathogen Sclerotinia sclerotiorum (Lib.) de Bary, is a major disease of canola and pulses in Australia. Current disease management relies greatly on cultural and chemical means of control. Timing of fungicide applications remains a challenge, because efficacy is dependent on accurate prediction of ascospore release and presence on the plant. The aims of this study were to determine the optimal temperature for carpogenic germination of S. sclerotiorum populations sampled from canola and lupin fields in southwestern Australia and characterize diversity using mycelial compatibility groupings (MCGs). Sclerotia were collected from four diseased canola and one diseased lupin field from across southwestern Australia. Forty sclerotia from each population were incubated at four alternating temperatures of 30/15, 20/15, 20/4, and 15/4°C (12-h/12-h light/dark cycle) and assessed every 2 to 3 days for a 180-day period. MCG groupings for populations were characterized using 12 reference isolates. Results indicated the time to initial carpogenic germination decreased as diurnal temperature fluctuations decreased, with a fluctuation of 5°C (20/15°C) having the most rapid initial germination followed by 11°C (15/4°C) followed by 16°C (20/4°C). Optimal germination temperature for all five populations was 20/15°C; however, population responses to other diurnal temperature regimes varied considerably. No germination was observed at 30/15°C. MCG results indicate extensive diversity within and between populations, with at least 40% of sclerotia within each population unable to be characterized. We suggest that this diversity has enabled S. sclerotiorum populations to adapt to varying environmental conditions within southwestern Australia.


2007 ◽  
Vol 52 (4) ◽  
pp. 271-280 ◽  
Author(s):  
Adrie F. G. Jacobs ◽  
Bert G. Heusinkveld ◽  
Aline Kraai ◽  
Krijn P. Paaijmans

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1095F-1095
Author(s):  
Steven C. Wiest ◽  
Roth E. Gaussoin

The following model simulates hourly temperature fluctuations at 6 Kansas stations: \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[T_{h}=\frac{(T_{x}-T_{n})}{2}\left[\mathrm{exp}\left(\frac{0.693h}{DL_{M}}\right)-1\right]+T_{n};{\ }0{\leq}h{\leq}DL_{M}\] \end{document} \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[T_{h}=\frac{(T_{x}-T_{n})}{2}\left[1+\mathrm{sin}\frac{{\pi}(h-DL_{M})}{2(23-DL_{M})}\right]+T_{n};{\ }DL_{M}{\leq}h{\leq}23\] \end{document} where h = time (hours after sunrise), DLM = 20.6 - 0.6 * daylength (DL), Th = temperature at time h, and TX and Tn = maximum and minimum temperature, respectively. Required inputs are daily TX and Tn and site latitude (for the calculation of DL). Whereas other models have been derived by fitting equations to chronological temperatures, this model was derived by daily fitting of hourly temperatures sorted by amplitude. Errors from this model are generally lower, and less seasonally biased, than those from other models tested.


1977 ◽  
Vol 20 (2) ◽  
pp. 0319-0326 ◽  
Author(s):  
L. D. Albright ◽  
N. R. Scott

1997 ◽  
Vol 88 (1-4) ◽  
pp. 269-277 ◽  
Author(s):  
Adrie F.G. Jacobs ◽  
Theo H. Jetten ◽  
DorothéC. Lucassen ◽  
Bert G. Heusinkveld ◽  
Nieveen Joost P.

2003 ◽  
Vol 57 (3) ◽  
pp. 385-398 ◽  
Author(s):  
David M. Kaplan ◽  
John L. Largier ◽  
Sergio Navarrete ◽  
Ricardo Guiñez ◽  
Juan Carlos Castilla

1999 ◽  
Vol 9 (2) ◽  
pp. 165-170 ◽  
Author(s):  
B. Ekstam ◽  
R. Johannesson ◽  
P. Milberg

AbstractSeed germination of the wetland emergent perennial Phragmites australis is stimulated by diurnally fluctuating temperatures. A germination experiment in darkness and light at different temperature regimes showed that P. australis germinated as well in darkness as in light over most of the temperature regimes tested. The germination requirements could partly explain why this species, despite a large annual production of small seeds, does not accumulate a persistent soil seed bank. A second experiment examined the effect of one to four diurnal temperature cycles with amplitude of fluctuations ranging from 0 to 30°C; diurnal mean temperature of 15°C. Germination in the absence of fluctuations was low, and logistic model estimates showed a positive effect of number of temperature cycles which was strongly influenced by amplitude size. For seeds that have fallen on moist ground during the winter, these laboratory results predict that a few large diurnal temperature fluctuations could be sufficient for onset of germination in the subsequently warmer spring period. Seeds that are located under water, however, are predicted to remain ungerminated until the water level falls. Hence, we suggest that the requirement for fluctuating temperature, in addition to being a sensor for ‘exposed’ seed sites, is also effectively acting as a germination timing mechanism.


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