Jojoba: Temperature Adaptation as Expressed in Growth and Leaf Function

1983 ◽  
Vol 10 (3) ◽  
pp. 299 ◽  
Author(s):  
IF Wardlaw ◽  
JE Begg ◽  
D Bagnall ◽  
RL Dunstone
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Vascular System ◽  
Starch Content ◽  
Dry Weight ◽  
Co2 Exchange ◽  
Temperature Adaptation ◽  
Pulse Labelling ◽  
Wide Range ◽  
Young Leaves

The adaptation of jojoba [Simmondsia chinensis (Link) Schneider] to temperature was studied under controlled conditions. Shoot extension and leaf area development reflected the very low rate of growth of this species, even under favourable conditions, and were stable with an increase in temperature from 20 to 30°C. However growth was markedly reduced at temperatures below 20°C and at 6°C there was no net gain in dry weight over a 42 day period. Root: shoot ratios were near unity and showed a small drop in response to increasing temperature. Leaves adapted to low temperature by an increase in thickness, specific leaf weight and starch content. Chlorophyll formation was retarded in young leaves developing at 15/10°C, but there was no sign of photodestruction of previously formed chlorophyll in mature leaves. Young leaves developing at 30/25°C had a very high chlorophyll a/b ratio of 9.5, but otherwise leaf chlorophyll was apparently normal (2.3-3.4) over a wide range of temperatures. Light saturation of net CO2 exchange (NCE) occurred at about 1000 �E m-2 s-1 for leaves grown over a wide range of temperatures and the maximum NCE of approximately 16 mg CO2 dm-2 h-1 (0.45 mg m-2 s-1) occurred between 19 and 25°C. Pulse labelling with 14CO2 indicated that low temperature (18°C) reduced the rate of transfer of 14C from the primary products of fixation to sucrose. The rate of movement of 14C-labelled photosynthate out of the leaf was negligible at 18°C, and reached only about 3% h-1 at 30°C. In the stems, shortly after 14CO2 uptake by the leaf, 86% of the 14C activity was in sucrose, indicating that this was the preferred form of translocate in the vascular system. However glucose was more abundant in the leaves than sucrose, particularly at low temperatures. Starch accumulated in the leaves at low temperatures, reaching nearly 30% of the dry weight at 18/13°C. Photosynthetic stability rather than active adaptation appears to form the basis of resistance to temperature stress in jojoba. With low rates even under optimal conditions this is essentially one of adaptation for survival rather than adaptation for production.

scholarly journals 'Momordica charantia’ introducing a new rootstock for grafted cucumber under low-temperature stress

2021 ◽  
Vol 35 (2) ◽  
Author(s):  
Saber Mohammadnia ◽  
Maryam Haghighi
Keyword(s):  
Low Temperature ◽  
Temperature Stress ◽  
Low Temperatures ◽  
Female Flower ◽  
Dry Weight ◽  
Momordica Charantia ◽  
Low Temperature Stress ◽  
Growth And Yield ◽  
Optimum Temperature ◽  
Harmful Effects

Cucumber is a sensitive vegetable to low temperatures. Grafting vegetables on different rootstocks can decrease the harmful effects of environmental stresses, including low-temperature stress. An experiment was performed to evaluate grafting cucumbers on different rootstocks at low temperatures. Cucumber growth and yield and photosynthesis traits were examined. Treatments were the optimum temperature (25±2°C), and cold temperature (15±3°C, Ts), and rootstocks, were Momordica charantia (Rmo), Cucurbita maxima (Rma), non-grafted (Rn) and self- grafted (Rs) with 4 replications. Shoot fresh and dry weight, chlorophyll, RWC, transpiration, decreased with temperature stress. The number of female flowers, electrolyte leakage, photosynthesis, stomatal conductance increased with Ts. First fruit emergence per plant, N, P, K, Mg concentration decreased with Ts stress. Transpiration, female flower, RWC, and stomata conductance, N, P, K, Ca, and phenol increased in Rma and Rmo. Mg was at the highest concentration in Rma and Na in Rn. All in all, using Rmo as well as Rma is recommended for rootstock as it causes more reproductive growth.

scholarly journals Low-temperature dynamics in a dye-doped polymer: correspondence between the data obtained by photon echo and single molecule spectroscopy

2018 ◽  
Vol 190 ◽  
pp. 04008
Author(s):  
Kamil Karimullin ◽  
Andrei Naumov
Keyword(s):  
Low Temperature ◽  
Single Molecule ◽  
Vibrational Relaxation ◽  
Low Temperatures ◽  
Photon Echo ◽  
Single Molecule Spectroscopy ◽  
Dye Molecules ◽  
Wide Range ◽  
Temperature Dynamics ◽  
Doped Polymer

Low temperature dynamics (tunneling and vibrational relaxation) in doped polyisobutylene film has been reinvestigated using 2-pulse incoherent photon echo (2IPE) and compared with single-molecule spectroscopy (SMS) data. It has been shown that in a very wide range of low temperatures the 2IPE gives optical dephasing times which correspond to the narrowest zero-phonon lines of single dye molecules.

Effects of light, temperature, and rate of desiccation on translucency in wheat grain

1968 ◽  
Vol 19 (3) ◽  
pp. 365 ◽  
Author(s):  
JA Parish ◽  
NJ Halse
Keyword(s):  
Low Temperatures ◽  
Dry Weight ◽  
Grain Filling ◽  
Wheat Grain ◽  
Low Light ◽  
Wide Range ◽  
Grain Drying ◽  
Drying Techniques ◽  
Laboratory Results ◽  
Grain Filling Period

Wheat grain was harvested at maximum dry weight and dried under various conditions in the laboratory. Results showed that opaque grain was produced by fast drying; translucency developed with slow drying. The effect of various temperatures when drying rate was constant was also measured. It was found that translucency developed more at high temperatures than at low temperatures. There was little "mottling" despite the wide range between treatments from entirely opaque to fully translucent grain. Drying techniques were found whereby grain samples different in texture but identical in other respects can be prepared. In other experiments wheat plants were grown in controlled light and temperature conditions during the grain-filling period. Results showed that at this stage low temperature and low light intensity favoured the development of translucency.

scholarly journals Testing and Applications of Non-Linear Wave Shaping Circuits Based on Zener Diodes at Cryogenic Temperatures

2017 ◽  
Vol 13 (4) ◽  
pp. 4910-4918
Author(s):  
A. M. Abd El-Maksood
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
The Other ◽  
Electronic Systems ◽  
Linear Wave ◽  
Cryogenic Temperatures ◽  
Temperature Variations ◽  
Wide Range ◽  
Non Linear ◽  
The Stability

            Applications of wave-shaping clipping circuits based on Zener diodes are of great interest in a wide range of modern electronic systems. As well, given the strong interest in space research and trips to distant planets, where the journey takes long periods. Therefore, the matter requires reliance on electronic systems with special specifications commensurate with the nature of the extremely low-temperature environments, down to cryogenic level (around 90 K). So, the present paper was concerned with studying the stability of the performance of different non-linear wave-shaping systems, based on silicon Zener diodes, whenever operates at very low temperatures down to cryogenic levels. From which, it is clear that for BZX79-C4V7 and BZX79-C5V6 Zeners, such electronic systems were shown to be insensitive to temperature variations. On the other hand, low breakdown voltage Zeners (BZV86-1V4 and BZX83-C3V6), the clipping edges were shown to be increased with lowering temperatures from 300 K down to 93 K. Finally, for Zener diodes with VZ greater than 6.0 V (BZX83-C6V8 and BZX55C9V1), the temperature coefficient is positive, so the clipping edges decrease with lowering temperatures, for the same range of temperatures.

scholarly journals 898 PB 532 LIGHT COMPENSATION POINT AND LOW TEMPERATURE AS STORAGE ENVIRONMENTS OF TRANSPLANTS

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 562e-562
Author(s):  
Chieri Kubota ◽  
Toyoki Kozai
Keyword(s):  
Exchange Rate ◽  
Low Temperature ◽  
Air Temperature ◽  
Low Temperatures ◽  
Storage Period ◽  
Dry Weight ◽  
Culture Conditions ◽  
Storage Method ◽  
Light Compensation Point

A storage method of transplants in vitro was developed using light compensation points in conjunction with low temperatures. Broccoli (cv. Ryokurei) plantlets, aseptically germinated and cultured for three weeks in vitro, were used as model transplants. Culture conditions were: 23C air temperature, 160 μmol m-2s-1 PPF, and 3.6 air exchanges per hour of the vessel. Prior to storage, light compensation points were determined at 3, 5, 10, and 15C for the plantlets cultured with or without 20 g liter-1 sugar in the medium. Plantlets were stored for six weeks at 5, 10, and 15C under either 0 or 2 μmol m-2s-1 continuous PPF. The light compensation points varied with air temperature and with medium sugar level. Plantlet dry weight during storage was best maintained by keeping CO2 exchange rate of the plantlets close to zero throughout the storage period. High transplant qualities were successfully preserved at light compensation points: 2 μmol m-2s-1 PPF at 5-10C without sugar, and at 5C with sugar in the medium. This method may be applicable for storage of other crop transplants, plug seedlings and cuttings as well.

Acremonium boreale n.sp., a sclerotial, low-temperature-tolerant, snow mold antagonist

1979 ◽  
Vol 57 (20) ◽  
pp. 2122-2139 ◽  
Author(s):  
J. Drew Smith ◽  
John G. N. Davidson
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Grass Species ◽  
Western Canada ◽  
Eastern Canada ◽  
Snow Mold ◽  
Typhula Ishikariensis ◽  
Wide Range ◽  
Ecological Importance ◽  
Fusarium Nivale

A previously undescribed, sclerotial, low-temperature-tolerant fungus with orange sclerotia, is common on a wide range of plant species and substrates in Western Canada. It is often associated with snow mold complexes. It has also been found in eastern Canada and Norway, indicating a circumpolar distribution. It is described as Acremonium boreale n.sp. Some isolates were antagonistic towards common snow molds, viz. Fusarium nivale, Sclerotica borealis, Typhula ishikariensis var. ishikariensis and var. canadensis, and the nonsclerotial low-temperature basidiomycete in culture at low temperatures. Although it was weakly parasitic towards two grass species, its main ecological importance seems to be as an invasive primary saprophyte on a wide range of substrates. It may play a significant role in determining the nature and intensity of damage in snow mold complexes.

OsSIG2A is required for chloroplast development in rice (Oryza sativa L.) at low temperature by regulating plastid genes expression

2019 ◽  
Vol 46 (8) ◽  
pp. 766 ◽  
Author(s):  
Yang Yu ◽  
Zhenling Zhou ◽  
Hanchun Pu ◽  
Baoxiang Wang ◽  
Yunhui Zhang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Chloroplast Development ◽  
Oryza Sativa L ◽  
Photosynthetic Apparatus ◽  
Development Stage ◽  
Specific Gene ◽  
Genes Expression ◽  
Young Leaves

The chloroplast is an essential photosynthetic apparatus that is more sensitive to low temperatures than other organelles. Sigma factors were revealed regulating specific gene expression for maintaining photosynthetic efficiency and adapting to physiological and environmental conditions. However, the regulatory mechanisms of SIG genes supporting chloroplast development under low temperature in rice have not yet been reported. Here, we uncovered the essential role of OsSIG2A in rice chloroplast development at low temperatures by a newly reported thermo-sensitive chlorophyll deficient 12 (tcd12) mutant, which exhibited albino leaves with decreased chlorophyll content and malformed chloroplasts at seedling stage under low temperature. OsSIG2A is a typical chloroplast-localised RNA polymerase sigma factor, and constitutively expresses in different rice tissues, especially for young leaves and stems. Moreover, the transcription level of both PEP- and NEP- dependent genes, which are necessary for chloroplast development at early leaf development stage, was greatly affected in the tcd12 mutant under low temperature. Taken together, our findings indicate that OsSIG2A is required for early chloroplast differentiation under low temperatures by regulating plastid genes expression.

scholarly journals Changes in Carbohydrate Composition of the Different Bulb Components of Nerine bowdenii W. Watson (Amaryllidaceae)

1996 ◽  
Vol 121 (2) ◽  
pp. 343-346 ◽  
Author(s):  
K.I. Theron ◽  
G. Jacobs
Keyword(s):  
Low Temperatures ◽  
Starch Content ◽  
Total Content ◽  
Dry Weight ◽  
Carbohydrate Composition ◽  
Weight Changes ◽  
Carbohydrate Analysis ◽  
Storage Carbohydrate ◽  
Sugar Levels

Flowering-size Nerine bowdenii bulbs were sampled from a commercial planting at 2-week intervals from 13 Aug. 1991 to 14 June 1992. They were dissected, the dry weight of foliage and leaf bases was recorded, and carbohydrate analysis was performed on the foliage leaves, leaf bases, and roots. Starch was the dominant storage carbohydrate, and leaf bases were the principal bulb structures where it was stored. Changes in starch content closely followed dry weight changes in the bulb. When exposed to low temperatures, starch was converted to sugars. Except for these high levels in the leaf bases, sugars, expressed both as concentration and total content, were low in bulb components, indicating continued export and conversion to starch. Low sugar levels during the period that florets in the current season's inflorescence develop to stage Late G (gynoecium elongated, carpels fused) is implicated in the abortion of the inflorescence.

Temperature and Ca2+ dependence of [3H]ryanodine binding in the burbot (Lota lota L.) heart

2006 ◽  
Vol 290 (2) ◽  
pp. R345-R351 ◽  
Author(s):  
Matti Vornanen
Keyword(s):  
Low Temperature ◽  
Binding Affinity ◽  
Low Temperatures ◽  
Normal Function ◽  
Dissociation Rate ◽  
Temperature Adaptation ◽  
Release Channel ◽  
Lota Lota ◽  
High Affinity ◽  
Gating Mechanism

Opening and closing of the cardiac ryanodine (Ry) receptor (RyR) are coordinated by the free intracellular Ca2+ concentration, thus making the Ca2+ binding properties of the RyR important for excitation-contraction coupling. Unlike mammalian cardiac RyRs, which lose their normal function at low temperatures, RyRs of ectothermic vertebrates remain operative at 2–4°C, as indicated by Ry sensitivity of contractile force. To investigate the mechanisms of low temperature adaptation of ectothermic RyRs, we compared Ca2+-dependent kinetics of [3H]ryanodine binding in cardiac preparations of a fish (burbot, Lota lota) and a mammal (rat). The number of ventricular [3H]ryanodine binding sites determined at 20°C was 1.54 times higher in rat than burbot heart (0.401 ± 0.039 and 0.264 ± 0.019 pmol/mg protein, respectively) ( P < 0.02), while the binding affinity ( Kd) for [3H]ryanodine was similar (3.38 ± 0.63 and 4.38 ± 1.14 nM for rat and burbot, respectively) ( P = 0.47). The high-affinity [3H]ryanodine binding to burbot and rat cardiac preparations was tightly coordinated by the free Ca2+ concentration at both 20°C and 2°C and did not differ between the two species. Half-maximal [3H]ryanodine binding occurred at 0.191 ± 0.027 μM and 0.164 ± 0.034 μM Ca2+ for rat and at 0.212 ± 0.035 μM and 0.188 ± 0.039 μM Ca2+ for burbot ( P = 0.65), at 2°C and 20°C, respectively. In two other fish species, rainbow trout ( Oncorhynchus mykiss) and crucian carp ( Carassius carassius), the Ca2+-binding affinity at 20°C was 4.4 and 5.9 times lower, respectively, than in the burbot. At 20°C, the rate of [3H]ryanodine binding to the high-affinity binding site was similar in rat and burbot but was drastically slowed in rat at 2°C. At 2°C, [3H]ryanodine failed to dissociate from rat cardiac RyRs, and at 10°C and 20°C, the rate of dissociation was two to three times slower in rat than burbot preparations. The latter finding is compatible with a channel gating mechanism, where the closing of the Ca2+ release channel is impaired or severely retarded by low temperature in rat but less so in burbot preparations. The stronger effect of low temperature on association and dissociation rate of [3H]ryanodine binding in rat compared with burbot suggests that RyRs of the ectothermic fish, unlike those of endothermic rat, are better able to open and close at low temperatures.

scholarly journals Chemical Composition of Turnip Roots Stored or Intermittently Grown at Low Temperature

1991 ◽  
Vol 116 (5) ◽  
pp. 818-822 ◽  
Author(s):  
V.I. Shattuck ◽  
Y. Kakuda ◽  
B.J. Shelp ◽  
N. Kakuda
Keyword(s):  
Ascorbic Acid ◽  
Low Temperature ◽  
Low Temperatures ◽  
Sucrose Concentration ◽  
Starch Content ◽  
Total Concentration ◽  
Total Sugar ◽  
Ascorbic Acid Concentration ◽  
Total Sugars ◽  
Total Sugar Concentration

Field and greenhouse studies were conducted to investigate the effects of low temperature on the starch, sugar, ascorbic acid, and glucosinolate (GS) concentration in turnip [Brassica rapa ssp. rapifera (Metzg.) Sinsk] roots. Field-harvested roots were stored at 0C for 2 and 4 weeks. In the greenhouse, plants were grown at 0 to 12C for parts of 11 days before harvest. Cold-stored roots decreased in both starch and total sugar concentration (sucrose, fructose, and glucose) when compared to freshly harvested roots. Greenhouse-grown plants subjected to low temperatures had roots with a similar starch content but with a higher concentration of total sugars than the control. In both experiments, the cold treatments induced a slight but significant increase in root sucrose concentration. The ascorbic acid concentration of roots was not affected by low temperature. In both the field and greenhouse studies, low temperature did not change the total concentration of the eight major GSs identified in peeled root “and peel tissues, but did alter the concentration of specific GSs.

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