Survival of Rhizoctonia solani AG‐1 IA,the Causal Agent of Rice Sheath Blight,under Different Environmental Conditions

The ability of Rhizoctonia solani AG‐1 IA, the causal agent of rice sheath blight, to survive in diseased rice straw and as sclerotia and mycelia was investigated. After storage for 10 months at 4°C, 25°C and non‐air‐conditioned natural room temperature (NRT, temperature range from 6°C to 35°C), sclerotia placed inside a desiccator, soaked in sterile water or immersed in wet paddy soil were viable. In contrast, only 15% of sclerotia in dry paddy soil survived. Survival of mycelia was severely affected by temperature and humidity. After 10 months in a desiccator at 4°C, 55% of mycelia samples could survive, whereas at 25°C and NRT, mycelial samples survived for only 7 and 5 months, respectively. However, mycelia stored in sterile water at constant temperatures (4°C or 25°C) survived for 10 months. A certain amount of UV radiation had no obvious effect on the survival of sclerotia or mycelia. The survival rate of the fungus in diseased rice straw stored for 16 months could reach 100% at 4°C, 50% at 25°C and 35% at NRT. The survival rates of the pathogen in diseased rice straw buried in dry, wet and flooded paddy soils after 10‐month storage at NRT were 75, 100 and 100%, respectively, indicating that soil humidity is a crucial factor for the survival of this fungus.     

The influence of temperature on light enhanced glycoalkaloid synthesis in potato

The influence of temperature on total glycoalkaloid (TGA) synthesis in tubers exposed to light (250 jumol m“² s”² PAR, Photosynthetically Active Radiation) or dark environments for 96 h was examined in three potato cultivars. Following 96 h light or dark the tubers were stored without light at 5°C or 24°C and TGA concentrations monitored over the subsequent 30 and 90 days. Exposure to light and cultivar were found to be major factors influencing TGA concentrations; temperature had no significant effect. TGA content in illuminated tubers of cvs ‘Pentland Hawk’ and ‘Kerrs Pink’ were significantly higher (P < 0.01) compared with tubers placed in the dark. TGA concentrations in cv. ‘Desiree’ increased significantly only following exposure to light at low temperatures (P < 0.05). Removal of tubers from storage at 5°C and immediate illumination at 24°C altered the ratio of glycoalkaloids in cvs ‘Pentland Hawk’ and ‘Kerrs Pink’. Regardless of cultivar and storage temperature TGA concentrations were higher at the end of the storage period compared with initial TGA concentrations. During storage TGA concentrations fluctuated widely and gradual accumulation of glycoalkaloids with time was rarely demonstrated except in cv. ‘Desiree’. Tubers stored at 24°C accumulated higher TGA concentrations than those stored at 5°C in cv. ‘Kerrs Pink’ but not in cvs ‘Pentland Hawk’ and ‘Desiree’. Tubers of cv. ‘Kerrs Pink’ exposed to light prior to storage accumulated glycoalkaloids more rapidly than unexposed tubers during storage at 24°C and occasionally at 5°C. Light enhanced glycoalkaloids are not degraded over time.     

Effects of anaerobiosis on ethylene production, respiration and flowering in iris bulbs

Ethylene production of iris bulbs (Iris hollandica cv. Ideal) was very low. When stored at 30°C, production was 12–20 pmol C₂H₄ (kg fresh weight)^?1 h^?1. Higher temperatures (35°C, 40°C) enhanced the ethylene production; a treatment with 40°C for ca 7 days caused a 3 times higher ethylene production than at 30°. During anaerobic storage (in 100% N₂) ethylene production was equal to that of control bulbs. When after a 7 day period of anaerobiosis the N₂ was replaced by air, a burstlike ethylene production was observed. Twenty-four h after the replacement, ethylene production was equal to control values again. The effects of this production of ethylene on mitochondrial respiration and flowering were investigated. When mitochondria were isolated immediately after the anaerobic treatment (before the enhanced ethylene production) alternative pathway capacity was not detectable, a situation also occurring in control bulbs. When mitochondria were isolated 24 h after the end of the anaerobiosis (after the ethylene burst) uninhibited respiration did not change significantly, but a capacity of the alternative pathway was observed. The increase in alternative pathway capacity after anaerobiosis was partly inhibited by 2,5-norbornadiene (NBD), an ethylene antagonist. Fermentation occurred during anaerobiosis: ethanol concentrations increased during the treatment and decreased when air was supplied. When bulbs were exposed to ethanol vapour the alternative pathway was induced but only when very high ethanol levels in the bulbs were reached. The amount of ethanol accumulated in the bulbs during a 7 day anaerobic treatment was far too low to explain the observed induction of alternative pathway capacity. Flowering percentages were enhanced after a 24 h treatment with ethylene and after a 7 day anaerobic treatment. NBD significantly inhibited the effect of exogenous ethylene and of anaerobiosis on flowering. Ethanol was not able to induce flowering. The burst-like production of ethylene after anaerobiosis probably is responsible for the effects on respiration and flowering.     

Temperature effects on ethanol and isopropanol utilization by Candida krusei

Candida Krusei has a optimum growth temperature of 37°C on SASOL ethanol-isopropanol mixture. The organism was unable to grow on isopropanol, but oxidized it partially to acetone in the presence and absence of ethanol. Growth at 40°C in the alcohol mixture was slightly faster than at 30°C over an ethanol concentration range of 0.43 to 3.6% (v/v), although at both temperatures the growth rate declined continuously with increasing concentration. At an ethanol concentration greater than 3.6% (v/v), the mixture was much more inhibitory to growth at 40 and 30°C. The inhibitory effect was due to the ethanol rather than the isopropanol. Metabolites such as acetate, acetaldehyde, and ethyl acetate accumulated in the medium, but the degree of accumulation depended upon the temperature and alcohol mixture concentration. At 40°C, acetaldehyde and acetate accumulated to a greater extent than 30°C on a 4.0% (v/v) synthetic alcohol mixture and this may also cause the greater inhibition at this temperature. The alcohol mixture is unsuitable for single cell protein (SCP) production in batch culture because of the low cell densities observed at all alcohol concentrations.     

Long-term storage stability of Beauveria bassiana ERL836 granules as fungal biopesticide

Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Cordycipitaceae) ERL836 has been commercialized under the name ChongchaeSak to control an agricultural insect pest, the western flower thrips Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), in the Republic of Korea. As soon as it was launched in 2017, it became a popular product and has received a positive response. However, study of the storage stability of the fungus ERL836 has yet to be investigated. To determine the optimum conditions for long-term storage, we assessed conidial viability and insecticidal activity of B. bassiana ERL836 according to storage temperature and culture substrate. Viability of B. bassiana ERL836 conidia from mycotized grains (millet and rice) stored at low (4 °C) and moderate (25 and 30 °C) temperatures was maintained at >85% for 24 and 18 months, respectively, along with insecticidal activity. In contrast, the samples stored at 37 °C showed low germination rate (about 80% germination rate for only 5 months). This result suggests that low and moderate temperatures (4 to 30 °C) conserve B. bassiana ERL836 viability and virulence.     

Changes in carotenoid and chlorophyll content of black tomatoes (Lycopersicone sculentum L.) during storage at various temperatures

Black tomatoes have a unique color and higher lycopene content than typical red tomatoes. Here, black tomatoes were investigated how maturation stage and storage temperature affected carotenoid and chlorophyll accumulation. Immature fruits were firmer than mature fruits, but failed to develop their distinctive color and contained less lycopene when stored at 8 °C. Hunter a^* values of black tomatoes increased with storage temperature and duration; storage of immature fruits at high temperature favored lycopene accumulation. Chlorophyll levels of black tomatoes declined during storage, but differences between mature and immature tomatoes stored at 12 °C were minimal. β-Carotene levels of black tomatoes increased during early storage, but rapidly declined beginning 13 d post-harvest. The highest lycopene and chlorophyll levels were observed in mature black tomatoes stored at 12 °C for 13 d; these conditions also yielded the best quality fruit. Thus, the unique pigmentation properties of black tomatoes can be precisely controlled by standardizing storage conditions.     

Production of mouse fetuses using spermatozoa exposed temporarily to high temperature or continuously to room temperature after freeze-drying in Na+-free/K+-rich EGTA buffer

Present study aimed to determine to what extent freeze-dried spermatozoa were able to withstand high-temperature conditions: transient increase in storage temperature and long-term exposure to room temperature. Mouse spermatozoa were freeze-dried in EGTA/Tris-HCl buffered solution alkalinized using KOH (K-ETBS, pH 7.7), and then stored for up to 7 months at 4 °C or 25 °C. After 2 months’ storage, some of the 4°C-stored spermatozoa were exposed to 40 °C for 1 week or 1 month, then again stored at 4 °C for the remaining storage period. Following storage, rehydrated spermatozoa were injected into mouse oocytes. The resulting zygotes were assessed for chromosome damage, in vitro development up to the blastocyst stage, and post-implantation development to normal fetuses on day 18 of gestation. In storage at 4 °C, one-week exposure to 40 °C had no adverse effect on the chromosome integrity and developmental competence compared to non-exposure to 40 °C (continuous storage at 4 °C). In contrast, one-month exposure to 40 °C caused an increasing level of chromosome damage (36%, P < 0.05) and reduced frequencies of blastocysts (54%, P < 0.05) and normal fetuses (36%, P < 0.05) compared to the frequencies obtained by continuous storage at 4 °C (15%, 82% and 52%, respectively). Storage at 25 °C resulted in accumulation of chromosome damage (27%, P < 0.05), leading to decreased blastocyst formation (63%, P < 0.05). But, the frequency of normal fetus (44%) was not significantly different from that obtained by continuous storage at 4 °C. Consequently, mouse spermatozoa freeze-dried in K-ETBS withstood temporary exposure to 40 °C for 1 week. Chromosome damage accumulated in spermatozoa during storage at 25 °C.     

浙江省仓贮稻谷大米真菌区系的研究

在浙江省采集仓贮稻谷及大米样品,共分离到真菌17属48种(不包括酵母菌)。其中:曲霉属(Aspergillus)18种,青霉属(Penicillium)10种,镰孢霉属(Eusarium)4种。研究表明:在浙江省地区之间,贮粮真菌种类无明显差异。稻谷加工成大米后,籽粒表面带菌量及内部带菌率均明显下降,其真菌区系以贮藏真菌为主。稻谷在贮藏前以田间真菌为主。贮藏1—4个月的稻谷因贮藏真菌的种类、数量明显增长,而田间真菌的种类和数量仍保持在较高的水平上,其表面带菌量及谷粒带菌率处于高峰期;贮藏1年以上的稻谷,其主要带菌种类为贮藏真菌,带菌量及带菌率明显下降。早籼谷和晚粳谷在相同贮藏条件下其带菌种类和数量基本一致。     

Physiological Responses of Apple Trees to Supraoptimal Root Temperature

Ungrafted apple rootstocks were grown in sand cultures at constant root temperatures between 20°C to 40°C. Temperatures of 30°C and above reduced root and shoot growth. Serious damage to the leaves occurred at 35°C and above. The O₂ consumption, CO₂ evolution and respiratory quotient (RQ) of the roots showed maximum values at 35°C. Different rootstock cultivars varied greatly in their susceptibility to damage by supraoptimal root temperatures apparently due to anaerobic respiration. The more susceptible ones differed from resistant types in the larger amount of ethanol they accumulated in their roots at supraoptimal root temperature, and the more severe reduction in the malic acid content of the roots at such temperature. Acetaldehyde was also found in roots and leaves at supraoptimal root temperatures, whereas the organic acid content of the leaves tended to decrease. Supraoptimal root temperature also caused a reduction of cytokinins in both roots and leaves accompanied by a reduction in the leaf chlorophyll content. This could be prevented by the application of kinetin or benzyladenine to the leaves. In a short experiment a rise in root temperature up to 40°C caused an increase in transpiration and a decrease in the resistance of the leaves to the passage of water vapor, whereas in prolonged experiments transpiration reached a maximum and leaf resistance a minimum at 30°C. The leaf water potential increased also with increasing root temperature. Leaf temperature increased with increasing root temperature, irrespective of increasing or decreasing transpiration rates.     

Fertility of Deep-frozen Maize (Zea mays L.) Pollen

On average, 50 per cent of maize pollen grains can be kept viableand almost 30 per cent remain fertile for up to a year whenthe water content on a fresh weight basis is reduced to about30 per cent of the original and the pollen is stored at –76or –196 °C. Over this period no significant differencewas found between storage at either temperature. Zea mays L., maize, pollen, fertility, viability     

Effect of freezing and freeze-drying on the viability and storage of Lilium longiflorum L. and Zea mays L. pollen

The freeze-preservation of pollen is dependent on the interaction of several factors such as freezing rate, thawing rate, freeze-drying temperature and duration, storage temperature and environment and rehydration rates. Changes in any of these variables affects the others directly or indirectly.Rapid freezing of pollen at rates of approximately 200 °C/min maintains the highest degree of viable pollen in combination with rapid thawing rates of 218 °C/min. Rapid cooling and slow rewarming resulted in a substantial loss of pollen viability. This might indicate that intracellular ice crystals formed during rapid cooling perhaps grow into larger ice masses during slow rewarming or storage at temperatures above ?50 °C.The germinability of pollen freeze-dried at temperatures below ?50 °C was also prolonged over that of the controls. Germination values for unfrozen pollen stored for 30 days at 0–5 °C averaged 50% for lily and 20% for corn. Freeze-dried pollen stored for 30 days at the same temperature yielded considerably higher viability percentages for both lily and corn pollen. Drying time is an important factor, perhaps indicating that residual moisture is critical. Freeze-dried pollen can be stored at higher temperatures than frozen and control pollen. Freeze-dried material stored for five months at 0–5 °C, upon slow rehydration yielded intact grains which has average germination percentages of 25 for lily and 15 for corn. The same pollen upon rapid rehydration showed rupturing of 20–40% of the cells and practically no germination.     

Effects of temperature on the cell wall and osmotic properties in dark-grown rice and azuki bean seedlings

The mechanism inducing the difference in growth rate under various temperature (10–50 °C) conditions was analyzed using rice and azuki bean seedlings. The growth rate of rice coleoptiles and azuki bean epicotyls increased as temperature increased up to 40 and 30 °C, respectively, and the elongation was retarded at a higher temperature. The cell wall extensibility of rice coleoptiles and azuki bean epicotyls also showed the highest value at 40 and 30 °C, respectively, and became smaller as the temperature rose or dropped from the optimum. The opposite tendency was observed in the minimum stress-relaxation time of the cell wall. On the other hand, the cellular osmotic concentration of rice coleoptiles and azuki bean epicotyls was lower at the temperature optimum for growth at 40 and 30 °C, respectively. When rice and azuki bean seedlings grown at 10, 20, 40, or 50 °C were transferred to the initial temperature (30 °C), the growth rate of coleoptiles and epicotyls was mostly elevated, concomitant with an increase in the cell wall extensibility. The growth rate was correlated with the cell wall mechanical parameters in both materials. These results suggest that the environmental temperature modulates the growth rate of plant shoots by affecting mainly the mechanical properties of the cell wall. Electronic Publication     

Effects of hot water treatments and storage temperatures on the ripening and the use of electrical impedance as an index for assessing post-harvest changes in mango fruits

The effects of hot water treatment and storage temperature (4°C, 13°C or 22°C) on the quality and impedance of outer and inner mesocarp of mango were assessed in two experiments during storage, impedance being a potential non‐destructive measure of tissue damage following heat treatment. Fruits were subjected to equivalent heat units at 36.5°C for 60 min plus 46.5°C for 43 min or 46.5°C for 90 min by hot water treatments (hwt) on the assumption of cumulative heat effects and a base temperature of 12–13°C. Fruit reflectance decreased whereas chroma and hue angle increased over storage time and also with increase in storage temperature. The yellow colour increased with a rise in storage temperature in hot water treated mangoes. Soluble solids content of mangoes held at 22°C was highest at 5 days of storage but decreased subsequently over storage time. Impedance of all fruits decreased with increase in frequency, storage temperature and time in store. The impedance of hwt mangoes was lower than that of non‐hwt fruits 8 h after immersion, but recovered almost to control levels on day 5 at 4°C or 13°C, but decreased gradually after 5 days at 13°C. Impedance of all mangoes stored at 22°C decreased continuously during storage. Impedance was higher in the inner mesocarp than outer pulp. Impedance of hwt fruits was poorly correlated with soluble solid content and chroma but well correlated with reflectance of fruit pulp at 22°C. Changes in impedance of mangoes are discussed in relation to physiological and biochemical changes that occur during heat treatment and storage.     

Phenolic metabolism in root slices of selected carrot cultivars

Carrot root slices, stored for 4 days at 20 °C reacted with a strong accumulation of total phenols, especially chlorogenic acid. A significant accumulation of isocoumarin content within the peel was observed in stored slices. Synthesis of phenols was accompanied by an increase in phenylalanine ammonia lyase activity, wound induced respiration and ethylene production. The great variability among the studied four cultivars was found concerning isocoumarin synthesis, PAL activity, respiration rate and ethylene evolution, but less distinct in the case of chlorogenic acid accumulation. The carrot slices obtained from freshly harvested roots were more sensitive to mechanical damage and short-term storage than those prepared from roots previously stored.     

Low temperature acclimation to chilling tolerance in rice roots

Rice seedlings (Oryza sativa L.) were subjected to low temperature pretreatment (LT-PT; 10°C) for various length of time (1, 2, 4, 6, 12, 18, 24 h) followed by a 48-h chilling temperature stress (2°C). Chilling temperature tolerance of rice roots was improved with increasing duration of LT-PT, but LT-PT longer than 12 h gave no additional improvement. Alcohol dehydrogenase activity and ethanol concentration in the roots were increased with increasing duration of LT-PT up to 12 h. Chilling tolerance was also improved by exogenously applied ethanol. These results suggest that LT-PT may increase chilling tolerance in rice roots owing to ethanol accumulation in the roots and LT-PT acclimation to chilling temperature may occur within 12 h.     

Xylose fermentation by Candida shehatae and Pichia stipitis: effects of pH,temperature and substrate concentration

The effects of temperature, pH and xylose concentration on the fermentation parameters of Candida shehatae and Pichia stipitis were evaluated. The optimum pH was in the region of pH 4–5.5, with an optimum fermentation temperature of 30°C. Maximum fermentation rates were reached at 50 g l⁻¹ xylose. A maximum volumetric ethanol productivity of about 0.9 g (l h)⁻¹ was obtained with both yeast strains. The ethanol yield of C. shehatae decreased considerably when cultivated above 30°C or when the xylose concentration was increased. Xylitol accumulated concomitantly. Xylitol production by P. stipitis was observed only during cultivation at 36°C. Whereas the ethanol yield of C. shehatae was usually about 75% of the theoretical maximum, it was 85–90% with P. stipitis.     

Polyamine content and chilling susceptibility are affected by seasonal changes in temperature and by conditioning temperature in cold-stored 'Fortune' mandarin fruit

‘Fortune’ mandarins are prone to develop pitting and necrosis upon exposure to low temperatures. We have examined the effect of field temperature during fruit maturation and the effect of conditioning temperatures (from 2 to 37°C) prior to cold storage on the content of polyamines (PAs) and on chilling susceptibility in order to understand the role of PAs in maturation and chilling tolerance of this citrus cultivar. Chilling susceptibility and the content of PAs were more affected by seasonal changes in field temperature than by the stage of fruit maturity. The highest putrescine (Put) and spermidine (Spd) content was found in fruits exposed to the lowest field temperatures. These fruits were in turn more susceptible to develop chilling injury (CI) after storage at 2°C. Spermine (Spm), however, decreased in attached fruit with time of exposure to temperatures below 12°C. Temperature pretreatments for 3 days above 20°C of fruits detached from the tree reduced CI, the more so the higher the conditioning temperature. Put and Spd increased with temperature conditioning in detached fruits, differing from the response of fruits attached to the tree. No direct relationship between induced levels of these PAs and the tolerance to CI was found. Levels of Put and Spd increased at temperatures (22, 30 and 37°C) which increased the tolerance and also at temperatures (6 and 12°C) which accelerated the appearance of chilling symptoms. In contrast, a significant increase in Spm levels was only found after conditioning at 30 or 37°C. After cold storage a general decline in PA levels occurred in all temperature‐conditioned mandarins. In most cases no significant differences among fruit exposed to effective and non‐effective pretreatments were observed. PA content increased again after transferring cold‐stored fruits to 20°C, whereas the CI index was barely affected. In conclusion, PA changes in the flavedo of ‘Fortune’ mandarins appear to be related to variations in temperature rather than to stage of maturity or tolerance to chilling.     

Effects of hypothermic hypoxia on anaerobic energy metabolism in isolated anuran livers

Many lower vertebrates (reptilian and amphibian species) are capable of surviving natural episodes of hypoxia and hypothermia. It is by specific metabolic adaptations that anurans are able to tolerate prolonged exposure to harsh environmental stresses. In this study, it was hypothesized that livers from an aquatic frog would possess an inherent metabolic ability to sustain high levels of ATP in an isolated organ system, providing insight into a metabolic system that is well-adapted for low temperature in vitro organ storage. Frogs of the species, R. pipiens were acclimated at 20 °C and at 5 °C. Livers were preserved using a clinical preservation solution after flushing. Livers from 20 °C-acclimated frogs were stored at 20 °C and 5 °C and livers from 5 °C-acclimated frogs were stored at 5 °C. The results indicated that hepatic adenylate status was maintained for 96 h during 5 °C storage, but not longer than 4–10 h during 20 °C storage. In livers from 5 °C-acclimated animals subjected to 5 °C storage, ATP was maintained at 100% throughout the 96-h period. Warm acclimation (20 °C) and 20 °C storage resulted in poorer maintenance of ATP; energy charge values dropped to 0.50 within 2 h and by 24 h, only 24% of control ATP remained. Lactate levels remained less than 25 μ mol/g dry weight in all 5 °C-stored livers; 20 °C-stored livers exhibited greater accumulation of this anaerobic end-product (lactate reached 45–50 μ mol/g by 10 h). The data imply that hepatic adenylate status is largely dependent on exposure to hypothermic hypoxia and although small amounts of ATP were accounted for by anaerobic glycolysis, there must have been either a substantial reduction in cellular energy-utilization or an efficient use of low oxygen tensions. Accepted: 24 August 1998     

Constant, Fluctuating and Effective Temperature and Seed Longevity: a Tomato (Lycopersicon esculentum Mill.) Exemplar

Tomato seeds with a moisture content of 16.4% were stored hermeticallyat one of five constant temperatures (10, 20, 30, 40, 50 °C)or in one of nine alternating temperature (24 h/24 h) regimes(10/30, 10/40, 10/50, 20/30, 20/40, 20/50, 30/40, 30/50, 40/50°C) for up to 224 d. In each regime, seed survival conformedto cumulative negative normal distributions and all 14 survivalcurves could be constrained to a common origin. Estimates ofthe constants C_Hand C_Qof the viability equation determined atconstant temperatures were 0.0346 (s.e. 0.0058) and 0.000401(s.e. 0.000096), respectively. The effective temperature forseed survival of each alternating temperature regime was alwaysmuch higher than the mean. Tomato seeds were also stored hermeticallyat 15.9% moisture content at 40 °C for 0, 7, 14, 21 or 28d before transfer to 50 °C. This investigation showed thatthe standard deviation of the subsequent survival curves at50 °C was unaffected by the duration of previous storageat 40 °C. The results of both investigations were consistentwith the hypothesis that loss in probit viability is solelya function of the current storage environment, with no effectof change in temperature per se. The application of the viabilityequation to seed survival in fluctuating environments was validatedagainst independent observations for rice in uncontrolled storageconditions. Copyright 2001 Annals of Botany Company Temperature, seed storage, longevity, moisture content, viability equation, tomato, rice     

The influence of housefly Musca domestica embryo age on viability in water and at low temperatures

The sensitivity of housefly Musca domestica L. (Diptera: Muscidae) embryos to storage at low temperatures (5 and 10 °C on moist sponges in Petri dishes) and in water at 26 °C was investigated to develop suitable protocols for the storage and transport of housefly eggs. The youngest embryos (aged 0–3 h) were the most sensitive to storage at 5 °C, with 45% survival after storage for 24 h. Storage of embryos aged 3–12 h at 5 °C for 24 h had no negative effect; longer storage resulted in significantly decreased larval survival (30–34% after 48–72 h, compared with 61% in the control group) and reduced hatching rates (83% after 72 h storage). No negative effects were observed when embryos aged 0–9 h were stored at 10 °C for 24 h, but this temperature did not completely inhibit development and eggs began to hatch if stored for longer than 24 h. All age groups of embryos showed high mortality after storage in water at 26 °C for 24 h, with the youngest embryos being least resistant to submersion.