THE EFFECT OF TEMPERATURE ON THE EXPRESSION OF FACTORS GOVERNING RUST REACTION IN A CROSS BETWEEN TWO VARIETIES OF TRITICUM VULGARE

1931 ◽  
Vol 5 (2) ◽  
pp. 200-207 ◽  
Author(s):  
J. B. Harrington

Two random populations of F2 plants of the cross Marquillo × Marquis were tested for the reaction of their F3 seedling progenies to form 21 of Puccinia graminis tritici in the greenhouse, at average daily temperatures of 69.7° F. (the warm test) for one population, and 60.6° F. (the cool test) for the other. In both tests Marquis was susceptible and Marquillo was resistant. In the "warm test" ten families of a total of 781 were resistant. In the "cool test" five families of a total of 301 were susceptible. In both cases the results fitted a 63:1 ratio excellently, indicating the operation of three main genetic factors for rust reaction. A genetic hypothesis is proposed that explains the results on the basis of the influence of low temperature in curtailing the action of three susceptibility factors A, B and C carried by Marquis. The results indicate that genetic studies on characters which are easily influenced by environmental conditions should be made under controlled conditions, after ascertaining in advance the general effects of different temperatures, etc., upon the hybrid material to be used.

Author(s):  
D. T. Gauld ◽  
J. E. G. Raymont

The respiratory rates of three species of planktonic copepods, Acartia clausi, Centropages hamatus and Temora longicornis, were measured at four different temperatures.The relationship between respiratory rate and temperature was found to be similar to that previously found for Calanus, although the slope of the curves differed in the different species.The observations on Centropages at 13 and 170 C. can be divided into two groups and it is suggested that the differences are due to the use of copepods from two different generations.The relationship between the respiratory rates and lengths of Acartia and Centropages agreed very well with that previously found for other species. That for Temora was rather different: the difference is probably due to the distinct difference in the shape of the body of Temora from those of the other species.The application of these measurements to estimates of the food requirements of the copepods is discussed.


1943 ◽  
Vol 21c (8) ◽  
pp. 235-248 ◽  
Author(s):  
A. A. Hildebrand ◽  
L. W. Koch

During the summer of 1942 sugar beets growing in an experimental plot at the Harrow laboratory were destroyed by a root rot of a type that apparently has been reported only once previously on this host in North America. Wilting of the foliage first attracts attention to affected plants, the roots of which show, externally, grayish-brown discoloured areas and, internally, fairly sharply-delimited, grayish to coffee-coloured lesions, affected tissues being more or less spongy in consistency. The causal organism, found to be a wound parasite, has been identified as Rhizopus arrhizus Fischer. The effect of temperature on the growth in culture and on the pathogenicity of this fungus and of representatives of the species, R. oryzae and R. nigricans, has been studied. It has been found that R. arrhizus and R. oryzae are relatively high temperature organisms, showing optimum growth at about 34° to 36 °C., and each capable of infecting and destroying artificially injured sugar beets most rapidly between 30° and 40 °C. R. nigricans, also a wound parasite is, on the other hand, a relatively low temperature organism showing optimum growth in culture at about 24° and displaying highest infection capability at about 14° to 16 °C.


2003 ◽  
Vol 25 (1) ◽  
pp. 197-198 ◽  
Author(s):  
Renata Aparecida de Andrade ◽  
Antonio Baldo Geraldo Martins

The jaboticaba tree (Myrciaria spp.) is originated from the center-south of Brazil and presents different types. It's a medium size tree, with tendency to form a crown with great number of branches. A characteristic considered as limitant for the commercial crop is the great juvenility, advicing producing good rootstocks of seedlings and graft wanted varieties, and other vegetative processes. With the purpose of evaluating the effect of temperature on germination of three clones of jaboticaba tree, was carried out a laboratorial research. It was observed influence of the temperature on germination. The highest percentage of germination was obtained at low temperature (15ºC and 20ºC). When it was used the temperature of 35ºC, two clones had only 8% of germination, while the other one was verified 35%. These values show the possibility of the ocurrence of variability among the clones of jaboticaba tree.


2014 ◽  
Vol 941-944 ◽  
pp. 1188-1191
Author(s):  
Qi Li ◽  
Chuan Zhu Leng ◽  
Si Xin Wang ◽  
Xi Hong Li ◽  
Lan Chen ◽  
...  

Taking ‘Fuji’ fresh-cut apples as material, studied on the effect of different temperatures (-2 ̊C,0 ̊C,2 ̊C and 4 ̊C) on storage quality of fresh-cut apples during 25 days. The results indicated that low temperature can significantly keep the storage quality of fresh-cut apples and inhibit browning. Moreover, compared to the other treatment groups, treatment at 0 ̊C better maintained the firmness, color, as well as higher contents of titratable acid and lower MDA content, which showed 0 ̊C can extent storage time.


1969 ◽  
Vol 47 (9) ◽  
pp. 747-753
Author(s):  
J. P. Harwood ◽  
H. D. Sanders

The effect of temperature over the range 28 to 37 °C was studied on the electrically induced responses in the neuronally isolated cortex of the cat. The positive burst response (PBR) was found to be insensitive to a fall in temperature with no change in threshold, although the duration of the response was increased at low temperature. The threshold for inducing the epileptiform afterdischarge (EAD) remained constant in some animals but decreased in half of the animals studied. As the temperature was lowered, the amplitude of the EAD decreased while the frequency increased. The epileptiform sustaining response (ESR) on the other hand was markedly sensitive to temperature and disappeared around 32 °C. The differential effect of temperature upon the PBR and ESR, which have similar parameters for their production, provides further evidence for the separate identity of the two responses.


1955 ◽  
Vol 33 (2) ◽  
pp. 197-201 ◽  
Author(s):  
G. J. Green ◽  
T. Johnson

The reactions of adult plants of 10 wheat varieties to stem rust (Puccinia graminis f. sp. tritici Erikss. & Henn.) races 11, 12, 15A, 15B-1, 15B-2, 15B-3, 17A, 29, 29A, and 139 were determined at temperatures of about 60° F. and 80° F. The varieties K338 AC 2.E.2 and K117A were resistant to all races at both temperatures. Redman was resistant to all races at both temperatures except for the races 15B-1, -2, -3, which attacked it at both temperatures. This variety was somewhat more susceptible to race 12 at the low than at the high temperature. The other varieties were more susceptible at the high temperature to one or more races to which they were resistant at the low temperature. McMurachy was more susceptible at the high than at the low temperature to races 15B-1, 15B-2, and 17A; Selkirk to races 15B-1 and 15B-2; Red Egyptian to races 15B-1 and 17A; Triticum timopheevi to races 15B-1, 15B-2, and 15B-3; Frontana × Thatcher II-47-37 to race 15B-1; Kentana to races 12 and 15B-2; and K58 to races 12, 15A, 17A, and 29. Since the resistance of these varieties broke down to different races, the effect of high temperature on the rust reaction of adult plants is specific for certain combinations of host variety and rust race.


2003 ◽  
Vol 46 (1) ◽  
pp. 135-141 ◽  
Author(s):  
Wilson Wasielesky Jr. ◽  
Adalto Bianchini ◽  
Cecilia. Castaño Sanchez ◽  
Luis Henrique Poersch

Studies were carried out to investigate the effect of temperature, salinity, ammonia, nitrite and nitrate on food consumption of pink shrimp Farfantepenaeus paulensis. Juveniles (0.2 - 0.4 g) were acclimated for 15 days in seawater with different temperatures, salinities and concentrations of ammonia, nitrite and nitrate. After the acclimation period, 20 shrimps per treatment were individualized in order to have their ration intake analyzed through the amount of ration offered and left over within a 24-hour period. Mean food consumption presented significant alterations (P<0.05) for the tested temperatures and nitrite concentrations, whereas for the salinity, ammonia and nitrate treatments, shrimp presented no alteration on food intake (P>0.05). According to the results obtained, temperature and nitrite affected F. paulensis food consumption. On the other hand, variables as salinity, ammonia and nitrate did not affect shrimp appetite. However, the possibility of this to happen over long periods, prejudicing the species culture in captivity, reinforced the necessity of regular water quality management.


1998 ◽  
Vol 58 (3) ◽  
pp. 491-495 ◽  
Author(s):  
TULIKA SRIVASTAVA ◽  
B. N. SINGH

Experiments were conducted to test the effect of temperature on oviposition in four species of the melanogaster group of Drosophila: D. ananassae, D. bipectinata, D. malerkotliana and D. biarmipes. In each species, two wild strains were used and eggs laid by females at three different temperatures (19°C, 24°C and 30°C) were counted for four days at 24 h interval. It is evident from the results that females of D. ananassae, D. bipectinata, D. malerkotliana and D. biarmipes lay low number of eggs at low temperature (19°C). Thus oviposition in these four species of Drosophila is significantly reduced at low temperature.


Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Xiuyuan Yang ◽  
Zhenlong Ge ◽  
Qiang Sun ◽  
Weiqiang Zhang

To quantitatively study the influence of temperature and strain rate on the brittleness of sandstone, the mechanical parameters of sandstone under different temperatures and strain rates are collected from the previous literature, and two empirical equations for calculating rock brittleness are used to quantitatively calculate and evaluate the brittleness of sandstone. The results show that both BI1 and BI2 can characterize the brittleness of sandstone, but the applicable conditions are different. The BI1 method is more accurate in calculating the variation in the sandstone brittleness with a strain rate, while the BI2 method is more accurate in calculating its variation with temperature. The brittleness of sandstone increases with the increase in the strain rate, especially when the strain rate exceeds 100 s-1. Under low-temperature conditions, the strength and brittleness of rocks increase due to the strengthening of ice. Under the condition of high temperature, the thermal damage to sandstone is intensified after 400°C, and the quartz phase changes after 600°C, which leads to the increase in microcrack density and the decrease in brittleness of sandstone. The conditions of low temperature and high strain rate are beneficial to the enhancement of sandstone brittleness.


From the experiments described by the author in a former paper, it appeared that a magnetized needle vibrated under exposure to the sun’s rays, came to rest sooner than when screened from their influence; that a similar effect was produced on a needle of glass or of copper, but that the effect on the magnetized needle greatly exceeded that upon either of the others. In the prosecution of this inquiry, the author has endeavoured to vary the experiments so as to obviate several causes of inaccuracy which might tend to invalidate the general conclusions he had before drawn. His first object was to compare the effects of the solar rays on an unmagnetized steel needle with one that was magnetized under the same circumstances; and the result was, that the latter was influenced in a more considerable degree than the former; and a similar difference was observed when the vibrations of a magnetized needle were compared with those of a needle made of glass or of copper. He ascertained that the diminution of the terminal arc of vibration, on exposure to the sun, was not occasioned merely by the heat imparted to the needles or surrounding medium, although this cause appeared in some instances to measure the intensity of the action which produced the diminution. In order to determine the comparative influence of the separate rays, he allowed them to fall on the needles after transmission through differently coloured fluids and glasses; but owing to want of opportunity, he was obliged to abandon the inquiry before arriving at any determinate results: though as far as they went, they appeared to confirm the conclusion that the effects were dependent on the degree of light, and not on that of the heat. The red rays, however, appeared to have a greater effect in diminishing the terminal arc than the blue. In order to determine the single effect of temperature, independently of light, the needles were vibrated in close vessels surrounded with water of different temperatures; the results showed that the terminal arc was increased in air of higher temperatures, which is the reverse of what takes place from the direct influence of the solar rays; and that this effect, instead of being different in the magnetized and in the other needles, was nearly the same in all, of whatever materials they consisted, and whether magnetized or not. The author next endeavoured to ascertain the effects produced on the axes of vibration by the action of a common fire; these, though much less in degree, he found to be similar in kind to those of the sun.


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