The effect of heterojunction properties of the diode temperature sensors on low temperature current transfer and temperature response curves

Author(s):  
Yu.M. Shwarts ◽  
A.V. Kondrachuk ◽  
M.M. Shwarts ◽  
L.I. Spinar ◽  
E.F. Venger
HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 908A-908
Author(s):  
Schuyler D. Seeley

Forcing plant material has long been used to determine dormancy intensity (DI) in woody species. Forcing with growth regulators may enhance this ability. Some forcing with naturally occurring hormones may be showing us the actual DI of certain materials. But, measurements of DI that use caustic, near-lethal treatments, or metabolic agents may be all or nothing breaking indicators acting on mechanisms other than the dormancy mechanism and thus not as useful in determining DI. It is possible to cause a meristem to break without completely breaking dormancy. Measurement of normal post-dormancy growth is necessary to determine the effect of a DI agent. DI breaking treatments that act on the dormancy mechanism can cause a temporary growth flush, but, unless the extent of that growth flush is measured and compared with the growth flush of the same normally broken plant material, its true effect remains unknown. In some plant material, the safest way to determine DI is to determine the chilling required to produce normal growth. This assumes that the vernalization requirement and temperature response curves are known for the plant in question. In peach, for instance, vernalization at 2C will cause seeds to germinate, but the resulting seedlings will be physiologically dwarfed. Vernalization at 6C or at 2C cycled with higher temperatures within the vernalization range results in normal seedlings. This indicates that, for chilling to progress normally, vernalization per se must be interspersed or concomitant with growth heat units. Vernalization, therefore, has a low temperature driven component and a heat requiring development and/or growth component. Vernalization driving conditions are slowly being elucidated. Each clarification requires modification of dormancy models. DI does not equal dormancy status!


2001 ◽  
Vol 78 (3) ◽  
pp. 371-373 ◽  
Author(s):  
Jongsoo Yoon ◽  
John Clarke ◽  
J. M. Gildemeister ◽  
Adrian T. Lee ◽  
M. J. Myers ◽  
...  

PLoS ONE ◽  
2022 ◽  
Vol 17 (1) ◽  
pp. e0261822
Author(s):  
Hongjun Xie ◽  
Mingdong Zhu ◽  
Yaying Yu ◽  
Xiaoshan Zeng ◽  
Guohua Tang ◽  
...  

Rice (Oryza sativa L.) is one of the most important species for food production worldwide. Low temperature is a major abiotic factor that affects rice germination and reproduction. Here, the underlying regulatory mechanism in seedlings of a TGMS variety (33S) and a cold-sensitive variety (Nipponbare) was investigated by comparative transcriptome. There were 795 differentially expressed genes (DEGs) identified only in cold-treated 33S, suggesting that 33S had a unique cold-resistance system. Functional and enrichment analysis of these DEGs revealed that, in 33S, several metabolic pathways, such as photosynthesis, amino acid metabolism, secondary metabolite biosynthesis, were significantly repressed. Moreover, pathways related to growth and development, including starch and sucrose metabolism, and DNA biosynthesis and damage response/repair, were significantly enhanced. The expression of genes related to nutrient reserve activity were significantly up-regulated in 33S. Finally, three NAC and several ERF transcription factors were predicted to be important in this transcriptional reprogramming. This present work provides valuable information for future investigations of low-temperature response mechanisms and genetic improvement of cold-tolerant rice seedlings.


Author(s):  
J. Antonio Guzmán Q. ◽  
G. Arturo Sánchez-Azofeifa ◽  
Benoit Rivard

Leaf temperature (Tleaf) influences photosynthesis and respiration. Currently, there is a growing interest on including lianas in productivity models due to their increasing abundance, and their detrimental effects on net primary productivity in tropical environments. Therefore, understanding the differences of Tleaf between lianas and trees is important for future of forest on whole ecosystem productivity. Here we determined the displayed leaf temperature (Td= Tleaf – ambient temperature) of several species of lianas and their host trees during ENSO and non-ENSO years to evaluate if the presence of lianas affects the Td of their host trees, and if leaves of lianas and their host trees exhibit differences in Td. Our results suggest that close to midday, the presence of lianas does not affect the Td of their host trees; however, lianas tend to have higher values of Td than their hosts across seasons, in both ENSO and non-ENSO years. Although lianas and trees tend to have similar physiological-temperature responses, differences in Td could lead to significant differences in rates of photosynthesis and respiration based temperature response curves. Future models should thus consider differences in leaf temperature between these life forms to achieve robust predictions of productivity.


2013 ◽  
Vol 40 (11) ◽  
pp. 1159 ◽  
Author(s):  
Yonggang Chi ◽  
Ming Xu ◽  
Ruichang Shen ◽  
Shiqiang Wan

A better understanding of thermal acclimation of leaf dark respiration in response to nocturnal and diurnal warming could help accurately predict the changes in carbon exchange of terrestrial ecosystems under global warming, especially under the asymmetric warming. A field manipulative experiment was established with control, nocturnal warming (1800–0600 hours), diurnal warming (0600–1800 hours), and diel warming (24 h) under naturally fluctuating conditions in a semiarid temperate steppe in northern China in April 2006. Temperature response curves of in situ leaf dark respiration for Stipa krylovii Roshev. were measured at night (Rn) and after 30 min of darkness imposed in the daytime (Rd). Leaf nonstructural carbohydrates were determined before sunrise and at sunset. Results showed that Rn could acclimate to nocturnal warming and diurnal warming, but Rd could not. The decreases in Q10 (temperature sensitivity) of Rn under nocturnal-warming and diurnal warming regimes might be attributed to greater depletion of total nonstructural carbohydrates (TNC). The real-time and intertwined metabolic interactions between chloroplastic and mitochondrial metabolism in the daytime could affect the impacts of warming on metabolite pools and the distinct response of Rn and Rd to warming. Projection on climate change–carbon feedback under climate warming must account for thermal acclimation of leaf dark respiration separately by Rn and Rd.


2006 ◽  
Vol 30 (4) ◽  
pp. 670-678 ◽  
Author(s):  
Rafael Vasconcelos Ribeiro ◽  
Eduardo Caruso Machado ◽  
Ricardo Ferraz de Oliveira

This study aimed to evaluate the response of photosynthesis (A), given by photosynthetic O2 evolution, to increasing temperature from 25 to 50ºC in sweet orange (Citrus sinensis (L.) Osbeck) leaf discs under non-photorespiring conditions. In order to evaluate the response of gross photosynthesis to temperature and the balance between photosynthetic and respiratory activities, respiration (Rd) rates were also measured, i.e. the O2 uptake in each temperature. In addition, light response curves of photosynthesis were performed by varying the photosynthetic photon flux density (PPFD) from 0 to 1160 µmol m-2 s-1 at 25 and 40ºC. The highest A values were observed at 35 and 40ºC, whereas the highest Rd values were noticed at 50ºC. A higher relationship A/Rd was found at 30 and 35ºC, suggesting an optimum temperature of 35ºC when considering the balance between photosynthesis and respiration under non-photorespiring condition. Overall, heat effects on plant metabolism were more evident when evaluating the relationship A/Rd. In light response curves, higher A values were also found at 40ºC under PPFD higher than 300 µmol m-2 s-1. Light saturation point of photosynthesis was increased at 40ºC, without significant change of quantum efficiency under low PPFD. Respiration was also enhanced at 40ºC, and as a consequence, the light compensation point increased. The better photosynthetic performance at 35-40ºC was supported by higher photochemical efficiency in both light and temperature response curves. The temperature-dependence of photosynthesis was affected by growth temperature, i.e. a high air temperature during plant growth is a probable factor leading to a higher photosynthetic tolerance to heat stress.


1983 ◽  
Vol 10 (6) ◽  
pp. 539 ◽  
Author(s):  
DH Greer

The development of frost hardiness in seedlings of P. radiata was followed using a photoperiod of 9 h and a constant day temperature of 12°C. The seedlings were preconditioned to a night temperature of 6.5°C for 35 days and 4°C for 7 days. The temperature was then reduced to -4°C for 66 days in one hardening treatment (designated 12/-4°C) and to 3°C for 136 days in another (designated 12/3°C). At the end of those periods, the night temperature was increased back to 6.5°C for a further 15 days. Frost hardiness was determined at regular intervals by exposing the seedlings to a series of artificial frosts. During the low temperature regime, frost hardiness developed continuously in seedlings from both treatments, from -5 to -9.5°C in the 12/3°C treatment and to -16.5°C in the 12/-4°C treatment. The rate of development of frost hardiness was constant at constant temperatures. Using a temperature response model, specific rates of hardening were estimated for both this and an earlier experiment, and found to be approximately linear against temperature. The analysis establishes that temperature controls the hardening process of P. radiata by regulating the rate of development of frost hardiness. Frost hardiness was also shown to be related to thermal time. Before this relationship could be useful in predicting frost hardiness of field-grown seedlings, the relative contribution of the photoperiod-induced and temperature-induced hardening in natural environments needs to be more clearly defined.


2020 ◽  
Vol 1 (6) ◽  
pp. 1988-1995
Author(s):  
Lucca B. Guimarães ◽  
Alexandre M. P. Botas ◽  
Maria C. F. C. Felinto ◽  
Rute A. S. Ferreira ◽  
Luis D. Carlos ◽  
...  

Precise optical temperature sensors based on luminescent Tb3+:Eu3+ tetrakis complexes with imidazolic counterions with high emission quantum yield values and low temperature uncertainty.


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