Non-freezing Temperatures Research Articles

Chilling Injury of Germinating Seeds and Seedlings

Abstract History. In 1897, Molisch first suggested the term that was translated as chilling injury to describe the injurious effects of low but non-freezing temperatures on certain plant species (40). More than 50 years were to pass, however, before it was recognized that a similar low-temperature injury might be sustained by germinating seeds. Earlier in this century, Kidd and West (32, 33) reported that soaking seeds of Phaseolus vulgaris L. at 10°C increased the amount of material leached from them and decreased germination compared with seeds soaked at 20°. In 1926, Kotowski (34) noted that the seeds of several warm-season vegetable crops would not germinate below 18°. During this period, it was generally acknowledged that reduced low-temperature germination as exhibited by seeds of most tropical and subtropical species was a consequence of seed infestation by soil-borne pathogens. For example, Leach (37) suggested that many soil organisms had lower optimum growth temperatures than the minimum temperature for seed germination. Thus, while seed germination was inhibited by low soil temperature, soil pathogens could readily grow, multiply and attack the seed.

The effects of cold on hemostasis

In vitro coagulation times and in vivo bleeding times were proportionally prolonged as the rabbit ear temperature was lowered from ambient temperature to 1°C. Cooling of the ear caused an increase in bleeding rather than the decrease generally attibuted to cold application. The effects of temperature on the various aspects of hemostasis are discussed, and the pertinent literature is reviewed. An optimal nonfreezing cold temperature which could consistently enhance hemostasis could not be determined.

Mortality of Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) non-freezing temperatures

AbstractEggs, larvae and pupae of Spodoptera littoralis (Boisd.) were exposed to five non-freezing constant temperatures (13°, 10°, 7°, 4° and 1°C). The period of exposure required to kill eggs and larvae, and to affect pupae seriously, was determined at each temperature. Distinction was made between dead pupae and pupae which were not killed but developed into deformed adults incapable of mating or laying fertile eggs. Probit line analysis was applied to the mortality results and response lines were plotted for all developmental stages at each constant temperature. Observed 100% mortality and computed LD 99 estimates showed that at all temperatures, except 1°C, resistance to cold was minimal at the egg stage, increased in maturing larvae and was at a maximum in the pupal stage, so that the order of the LD 99 values was: pupae (dead)>larvae>eggs. At 1°C the order was: pupae (dead)>30-day-old larvae>eggs>15-day-old and 1-day-old larvae. The LD 99 (days) value decreased with decreasing temperature for all larval stages and for pupae; and for eggs it was greater at 1°C than at 4° and 7°C.

Effects of temperature and humidity on pitting injury of eggplant fruits during storage

It has been known that eggplant fruits show the typical symptoms of chilling injury on being stored at low but non-freezing temperature. Using this material authors have been studying the mechanism of chilling injury, and this paper reports effects of temperature and humidity on pitting injury during storage.1) When eggplant fruits were stored at 1°C, 6°C, 10°C, and 20°C, the storage period for salable condition of fruits were 9, 11, 21, and 23 days, respectibly. The major factors in decreasing of market quality were a pitting injury at 1°C and 6°C and decay of calyx at 10°C and 20°C.2) The occurrence of pitting injury was observed at only 1°C and 6°C. Pitting injury was less frequent on unripe fruits (5-7 days after flowering) and overipe fruits (24-27 days after flowering) and pitting injury was more frequent at proper harvesting stage (14 days after flowering). Pitting injury decreased to late harvesting season and holding at 10°C before storage at 1°C.3) Dark sheet subside was observed at low humidity storage and pitting injury was observrd at high humidity storage at 1°C. Under the microscope, it was found that pitting injury commenced with deformation and browning of cells which located several layers inside surface and dark sheet subside commenced with deformation and browning of pericarp cells.4) It was recommended that eggplant fruits were stored at 10°C-20°C and high humidity condition.

Effect of Cold Temperatures on the Viability of Chromobacterium violaceum

The effect of low, nonfreezing temperatures on the viability of five strains of Chromobacterium violaceum was studied. The viability of cultures grown at 30 C was determined after exposure to various diluents held at 0 to 2 C. A culture diluted at its growth temperature served as the control. Cells of strain N were most sensitive in the early part of the exponential phase of growth. Cells of strains 252 and 341 were most sensitive in the late exponential, early stationary phase of growth. Cells of strain 9 showed greatest loss of viability during the maximal stationary phase. Strain 69 was completely resistant throughout its growth cycle to cold injury. Cell viability was much greater in buffered salts solution than in distilled water, broth, or physiological saline, whether cultures were diluted at room temperature or in the cold. The proportion of cells surviving after exposure to cold, however, was the same regardless of the composition of the diluent. Loss of viability was progressive at 0 to 2 C and reached a maximum after 2 hr. There was no loss of viability of cells exposed to 20 C, but there was some loss at 12 C. Strain 341 cultivated at 15 C was much less sensitive to 0 to 2 C than when it was cultivated at 30 C. The composition of the growth medium seemed to have no effect on the survival of cells exposed to cold. The polyamines, spermine and trimethylenediamine, as well as erythritol and sucrose, exerted some protective action against the effects of cold but not uniformly for all strains studied.

Effect of Cold Temperatures on the Viability of Chromobacterium violaceum

The effect of low, nonfreezing temperatures on the viability of five strains of Chromobacterium violaceum was studied. The viability of cultures grown at 30 C was determined after exposure to various diluents held at 0 to 2 C. A culture diluted at its growth temperature served as the control. Cells of strain N were most sensitive in the early part of the exponential phase of growth. Cells of strains 252 and 341 were most sensitive in the late exponential, early stationary phase of growth. Cells of strain 9 showed greatest loss of viability during the maximal stationary phase. Strain 69 was completely resistant throughout its growth cycle to cold injury. Cell viability was much greater in buffered salts solution than in distilled water, broth, or physiological saline, whether cultures were diluted at room temperature or in the cold. The proportion of cells surviving after exposure to cold, however, was the same regardless of the composition of the diluent. Loss of viability was progressive at 0 to 2 C and reached a maximum after 2 hr. There was no loss of viability of cells exposed to 20 C, but there was some loss at 12 C. Strain 341 cultivated at 15 C was much less sensitive to 0 to 2 C than when it was cultivated at 30 C. The composition of the growth medium seemed to have no effect on the survival of cells exposed to cold. The polyamines, spermine and trimethylenediamine, as well as erythritol and sucrose, exerted some protective action against the effects of cold but not uniformly for all strains studied.

Physiological studies of chilling injury in natsudaidai (Citrus natsudaidai HAYATA) fruits. I

Citrus fruits such as oranges, lemons, and grapefruits suffer physiological injury when subjected to low but non-freezing storage temperatures. On natsudaidai fruits, of which production is a considerable amount among Japanese citrus fruits, there has been little available report concerning low temperature storage. Our preliminary experiments, purported to establish optimum storage temperature, showed occurrence of typical chilling injury on natsudaidai fruits. The present study was carried out to confirm this phenomenon in reference to its physiological aspects.(1) When natsudaidai fruits were stored at 1-1.5°C for two month or longer, chilling injury developed gradually. On the peel of chilled fruits brown pitting appeared and the fruits became susceptible to decay. Darkening of whole peel color was also found. Furthermore, prior to the appearing of visible injury during low temperature storage, the fruits increased susceptibility to microorganisms, and when transferred to 20°C severe decay took place rapidly. At 6°C, the fruits were stored without chilling injury and kept good external appearance for three months. At 13°C, half of fruits decayed during the storage of three months.(2) Respiration rate of fruits decreased with duration of storage at 6°C, showing the same tendency as ordinary citrus fruits. On the contrary, the respiration of fruits stored at 1°C exhibited continuous increase, and reached higher rate than that of the fruits at 6°C in the latter portion of storage period. When the fruits transferred from 1°C to 20°C, spur of carbon dioxide output was observed, and the degree of stimulation was more conspicuous with increasing exposure time at low temperature.(3) Respiration of flavedo tissue slices was measured at 30°C. Respiration rate of the slices prepared from 1°C-stored fruits was higher than that from 6°C- or 13°C-stored fruits especially in the latter portion of storage period. Respiratory quotient became lower than unity in the tissues from non-chilled fruits. However, at 1°C the RQ value remained at high level throughout the storage period.(4) Because the measurement was carried out with externally sound fruits, the results mentioned above suggest that abnormality of metabolism may have occurred in the healthy-appearing fruits during the 1°C storage.(5) Ascorbic acid content remained higher in the fruits stored at low temperature, indicating no relation to mechanism of chilling injury.(6) Potassium ion leakage from flavedo tissue slices suspended in water or sucrose solution was measured to detect the change of cellular permeability during the low temperature storage. However, no relation was found between the leakage and cause of chilling injury.(7) Prior to low temperature storage, a portion of fruits were treated with N6-benzyladenine, gibberellin, indoleacetic acid, and fruit wax. No effect was found to prevent the development of chilling injury with all chemicals used.

X-Ray Inactivation of Yeast at Freezing Temperatures

Several recent investigations have dealt with the dependence of X-ray sensitivity of unicellular organisms suspended in aqueous media on the temperature during irradiation (1-3). It has been found that X-ray sensitivities at freezing temperatures are materially less than those typical for cells at nonfreezing temperatures. Stapleton and Edington (2) have found that for E. coli the phase change from liquid (0? C) to solid (-22? C) decreases the radiosensitivity by a factor of approximately 3. A decrease in the irradiation temperature to -72? C further lowers the sensitivity by 17 %, and to -196? C by another 50 %. This general picture was also found by Houtermans for the same organism (3). Wood has found that in haploid yeast the sensitivity decreases twofold in the region from 0? C (liquid phase) to -10? C (solid phase) and decreases an additional 25 % in going from -10? to -30? C (1). The explanation that has been given for these results is that a substantial part of the radiation inactivation due to indirect effects mediated by and through the water of the biological system is lost in frozen suspensions. It has been assumed that at freezing temperatures diffusion processes would be materially decreased because of the loss of water through freezing and because of a diminution in diffusion constants in the ice phase. In this paper the radiosensitivity of haploid yeast in the temperature range 10? to -72? C is examined. As previously reported, the above general pattern is followed down to approximately -30? C. In the range from -30? to -72? C, however, there is a drastic increase in radiosensitivity (2.5-fold) to a value typical of the liquid phase. To explain these apparently anomalous results it is necessary to consider not only the degree of cellular freezing, but also the position of the frozen water, whether within or without the cell wall.