Low Night Temperature Research Articles

昼夜温がトウガラシ属のつぼみおよび花の脱離に及ぼす影響

Effect of day/night temperature on bud and flower abscission in pepper (Capsicum annuum L.) was studied using four varieties, ‘New Ace, ’ ‘Fushimi Amanaga, ’ ‘Thai Chilli’ and ‘Oriental Glory.’ Plants were grown in phytotrons with day/night temperatures 37/27, 32/22, 27/17°C under natural day light. Bud-abscission percentage increased with increasing the temperature especially in Thai Chilli, while no apparent relationship between temperature and flowerabscission percentage was observed, indicating flower buds were susceptible to high temperature. Also, the effect of different night temperatures (27, 22, 17°C with a constant day temperature of 37°C) and different day temperatures (37, 32, 27°C with a constant night temperature of 22°C) on bud and flower abscission of Thai Chilli was investigated, individually. In the former experiment, night temperature was found to have effect on only flower-abscission percentage. In the latter experiment, bud-abscission percentage increased with increasing day temperature.The effect of two plant growth regulators on bud and flower abscission were examined using the var. New Ace and Thai Chilli under two day/night temperatures (37/27 and 27/17°C) . Application of maleic hydrazide (MH) and silver thiosulfate (STS) did not affect bud and flower abscission in New Ace. Mean while, application of vegetative growth inhibitor, MH, affected flower abscission in Thai Chilli.These results indicate that, bud and flower abscission of peppers under high temperature might be caused by a hormonal mechanism, a failure in fertilization of the flower and competition for assimilates between bud and young leaves. Low night temperature and application of plant growth regulators might have an effect on the competition for assimilates, resulting in bud and flower abscission.

イチゴ実生の夜冷短日処理による花成誘導と早生性の選抜

イチゴ実生の夜冷短日処理による花成誘導と早生性の選抜

Respiration of geranium and petunia in response to low night temperature

The morphology and rate of development of some bedding plant species is altered by growth at low night temperatures. This cultural practice is of interest because it results in lower greenhouse energy costs and higher productivity at low photosynthetic photon flux. Low night temperatures and changes in the carbohydrate content of the plants may alter energy losses from maintenance respiration. To test this hypothesis, seedlings of geranium (cultivar ‘Red Elite’) and petunia (cultivar ‘Snow Cloud’) were grown at day temperatures of 25°C and night temperatures of either 7°C or 15.5°C. Thereafter, CO 2 evolution in the dark at 21°C was measured and starch, soluble sugar and total nitrogen levels were determined. The respiration rates at 21°C of plants grown at 7°C night temperature were consistently higher than those of plants grown at 15.5°C night temperature. Plants grown at the low night temperature had higher starch and soluble sugar levels, even after 112 h in darkness. Effects of night temperature in winter on maintenance respiration and reserve carbohydrate accumulation are discussed.

Hardening and Dehardening of Lolium perenne in Response to Fluctuating Temperatures

Hardening and dehardening responses of two contrasting varieties of Lolium perenne, measured as LT 50 , estimates, were followed in fluctuating temperature environments. Unhardened seedlings were exposed to hardening environments for 7, 14, and 21 d in all combinations of 2, 4, 6, 8 and 10 o C with either high day and low night temperatures or low day and high night temperatures

EFFECT OF TEMPERATURE ON KIWIFRUIT MATURATION

In New Zealand, harvest maturity for kiwifruit is determined by the soluble solids concentration (SSC) of juice (minimum 6.2%). Commercial maturity differs in various regions of the country within each season and between years and may be due to differences in temperatures during growth. Mature `Hayward' kiwifruit vines were grown in controlled environment temperature treatments of 14/8, 18/8, 22/8, 26/8, 14/12 and 22/12C to determine whether the increase in SSC at low night temperatures recorded in a related study was a result of the mean temperature, the min. daily temperature, or the magnitude of the max./min. temperature difference. Measurement was made of fruit size, firmness, starch and total sugar concentrations in the fruit at 10 day intervals. SSC increased fastest with the coolest mean temperature irrespective of the min. temperature or max./min. difference. In the coolest treatment the concentration of starch decreased rapidly with a rise in total sugar, in the warmest treatment the change in the carbohydrate components was slower. Data will be used to predict harvest date at commercial orchard sites based on field temperature measurements.

Branching, flowering and pod-set patterns in snap-bean (Phaseolus vulgaris L.) as affected by temperature

The effect of temperature on branching, flowering and pod-set patterns of determinate snap-bean (Phaseolus vulgaris L.) cultivars has not been well documented. In this work, well-defined rigid gradients of branching and flowering were found in determinate snap-bean. However, in spite of the great developmental stability of these gradients, pod production and distribution along the main axis of the bean plant was highly plastic in its response to environmental conditions. Under controlled conditions, high temperature (32/27 °C) drastically reduced pod production even though branching and flowering were greatly increased. Under lower temperatures most (>50%) mature pods were produced by branches of the first and second trifoliolate leaves. Low night temperature (12 °C) increased branching and relative pod production by more basal nodes, mainly by primary leaves branches. Large shifts in the relative contribution to mature pod production by main inflorescence and branches at different nodal positions along the main shoot were observed also in the field. It appears that in determinate cultivars of snap-bean the rigid gradients in branching and flowering do not limit pod production because of compensatory rapid developmental adaptation to transient environmental stresses. Key words: Snap-bean, Phaseolus vulgaris L., branching, pod-set, temperature

Effect of Maize Maturity on Radiation‐Use Efficiency

AbstractMaize (Zea mays L.) production has expanded into short‐season regions but it is not known whether the radiation‐use efficiency (RUE, g MJ−1)1 of new early hybrids differs from those grown in traditional maize‐growing regions. In this study, spectral reflectance measurements were used to derive estimates of photosynthetically active radiation (PAR) absorbed to compare the RUE of 10 maize hybrids that varied in adaptation from Iowa 110‐d relative maturity to the earliest 60‐d relative maturity hybrids commercially available. Reflectance measurements were made radiometrically in the visible and near‐infrared regions of the electromagnetic spectrum at approximately weekly intervals in 1985, 1986, and 1988. The 10 maize hybrids were grown at three densities at Lethbridge, Alberta, on an irrigated silty clay loam soil (Typic Haploboroll). The Scattering by Arbitrarily Inclined Leaves (SAIL) model of canopy reflectance was inverted to produce daily estimates of the fraction of absorbed PAR, p. Multiplying p by daily PAR irradiance gave daily estimates of absorbed PAR (APAR, MJ m−2), which were summed for the season. Radiation use efficiency was obtained by dividing whole‐plant yield at harvest by seasonal (emergence to harvest) APAR. Averaged over years, hybrids, and densities, RUE was 2.3 g MJ−1. Radiation‐use efficiency increased with population density across hybrids regardless of maturity. Seasonal RUE was lower than reported in the literature but there is evidence that chilling injury due to low night temperatures at the high elevation and semi‐arid location of the study reduced photosynthesis. The results suggest that spectral reflectance can be used effectively by breeders to identify hybrids that are more efficient users of PAR and that maize hybrids resistant to chilling injury may be needed at high latitudes.

Premature Leaf Chlorosis in Cucumber Associated with High Starch Accumulation

Summary Premature leaf chlorosis is a physiological disorder observed in winter-grown cucumber plants and is visually distinct from senescence-related chlorosis. Yellow leaves are characterized by high levels of starch and most of the soluble sugars, including glucose, fructose, galactose, galactinol and inositol. Levels of stachyose were found to be similar in healthy and chlorotic leaves. Electron micrographs of yellow leaves showed that plastids were filled with starch and that only traces of the thylakoid membrane structure remained. Starch levels in cucumber leaves followed a diurnal cycle and morning levels were higher following a low-night-temperature treatment (5 °C minimum) as compared with a high-night-temperature treatment (20 °C minimum). These results are consistent with the hypothesis that this form of chlorosis is due to an accumulation of photosynthate in the source leaf and an overaccumulation of starch in the chloroplast. Reduced export from the source leaf in response to low night temperature may be one of the factors responsible for the symptoms.

Miniature Gladiolus Cultivars Bred for Winter Flowering

Most of the commercial gladioli in the world have been bred to provide cut flowers in the summer. Growing these cultivars in subtropical and Mediterranean climates during the winter months frequently results in low-quality flowers (Halevy, 1985; Magic and Cowperthwaite, 1954; McKay et al., 1981; Shillo and Halevy, 1976a). The failure to grow high-quality gladiolus flowers during the winter months has been attributed to the sensitivity of these summer cultivars to low light intensities (Shillo and Halevy, 1975, 1976b), short photoperiods (Shillo and Halevy, 1976c, 1981), and the combined effect of low irradiance with low night temperatures (Halevy, 1985; Shillo and Halevy, 1963) during flower development. The European restriction on the importation of cut flowers to the winter months generated the need to develop gladiolus cultivars selected to produce high-quality flowers under winter conditions. [In December, the average daylength in Tel-Aviv, Israel, is 10 h and 5 rein, with an average irradiance of 850 to 1000 μmol·s ·2 (400-700 nm).] In addition, the flower industry required a smaller, lightweight flower able to respond favorably to higher density planting, produce higher yields, and reduce shipping costs. In response to the demands of the cut flower industry and the renewed interest in smaller cultivars (Barnard, 1972; Halevy et al., 1984), a new group of miniature gladiolus was developed for the cut flower market. Their main properties are: winter flowering, light weight, and attractive variety of colors. The group was nicknamed ‘Orchidiola’ (orchid glads) by the Israeli flower industry. The name was inspired by the petal shape and the variation

Low night temperatures have a differential effect on the diurnal cycling of gene expression in cold–sensitive and tolerant tomatoes*

Abstract. Comparisons were made between the changes in mRNA levels induced by low night temperatures in the cold–sensitive tomato and two altitudinal ecotypes of the wild species L. hirsutum. Changes in mRNA levels were detected by resolving in vitro translation products of poly(A)+ RNA by 2‐D PAGE. The treatment was applied by first growing plants in a thermoperiod of 25/18°C and then switching to 25/6°C. All tomatoes displayed a diurnal cycling in which a set of mRNAs accumulated at the end of the 18°C nights, whereas another accumulated at the end of the 25°C days. The accumulation of night specific mRNAs was inhibited by 6°C nights in the cold sensitive tomatoes while that of the tolerant one was only marginally affected. All tomatoes showed a similar reduction in the apparent turnover rate of the day specific mRNAs during the 6°C nights. Finally, low night temperatures induced the accumulation of six to eight mRNAs in all genotypes. This number increased by 15 in L. esculentum after the seventh night and are likely involved in stress response rather than acclimation/tolerance. The tomato is proposed as a genetic model to discriminate genes involved in acclimation/tolerance from those involved in stress response.

ファレノプシスにおけるＣＡＭ型光合成への葉齢・花序・水分・温度・光条件の影響

Effects of some factors on CAM (Crassulacean acid metabolism) photosynthesis in Phalaenopsis were investigated by measuring diurnal CO2 exchange patterns. Following results were obtained.1. The diurnal CO2 uptake pattern of Phalaenopsis leaves is nearly typical of CAM photosynthesis. Leaf age had no influence on CAM photosynthesis; the youngest leaf absorbed slightly more CO2 during the day and less at the night than did mature leaves. Although the third and forth leaves were shaded by the upper leaves, they fixed CO2 via CAM photosynthesis at rates similar to the upper two leaves fully exposed to light.2. Formation of inflorescence did not influence the diurnal pattern of CO2 uptake of CAM photosynthesis. But the plants without inflorescence had lower activities in CO2 uptake via CAM photosynthesis than those with inflorescence.3. When the day and night temperature were kept constant, 20°C was the optimum for the night time CO2 uptake. Although the day time CO2 uptake decreased as temperature increased, total CO2 uptake during 24 hr was maximized at 20°C. Higher day and lower night temperatures (25°15°C) were more favorable than a constant 20°C with respect to CO2 assimilation of CAM photosynthesis at night or during the entire day. Low day time temperature of 10°C depressed CO2 uptake rates at night and promotes during the day so that the Phalaenopsis leaves approximated those of plants with C3-photosynthetic system.4. The day and night time CO2 uptake increased with higher light intensity up to 130μE/m2/sec. Above 130μE/m2/sec the capacity of leaves to assimilate CO2 at night was saturated and that during the day became lower. Therefore, CAM photosynthesis in Phalaenopsis has a lower light saturating point than other plants.5. Under our growing conditions, withholding water for 10 days resulted in a severe water stress which significantly depressed CO2 uptake both day and night.

Cold-Induced Photoinhibition Limits Regeneration of Snow Gum at Tree-Line

Cold-Induced Photoinhibition Limits Regeneration of Snow Gum at Tree-Line

Morphology of bedding plants in response to low night temperature and energy use implications

Seedlings of bedding plant crops were grown in greenhouses, January–May 1987 and 1989, at day air temperatures of 27 ± 3°C (9 h) and either 7 ± 3°C or 18 ± 3°C night air temperatures (15 h). Morphological evaluations of the crop response to night temperatures were taken and calculations of fuel energy required to operate greenhouses at 7 and 18°C were determined. Crops which grew well at 7°C and which were short, compact and bloomed quickly were mimulus (cultivar ‘Yellow Flower’), marigold (cultivars ‘Aurora’, ‘Janie’) and petunia (cultivars ‘Crimson’, ‘Joy’). Other crops which grew well at 7°C, but took longer to bloom were geranium (cultivars ‘Cardinal Orbit’, ‘Orbit Glow’, ‘Pink Elite’, ‘Violet Elite’), marigold (cultivar ‘Perfection’), pansy (cultivar cultivar ‘Universal Mix’) and verbena (cultivar ‘Springtime’). Crops which were stunted or took too long to bloom were impatiens (cultivar ‘Accent’), dianthus (cultivars ‘Big Eye Crimson’ and ‘Scarlet’, ‘Magic Charm’, ‘Princess’), snapdragon (cultivars ‘Liberty’, ‘Pixie’) and zinnia (cultivar ‘Peter Pan’). Fuel savings at 7 vs. 18°C were 9.71 of fuel oil per square meter in January, 8.8 in February, 9.6 in March and 1.8 in April.

ABSCISSION PATTERNS FOR FIVE EARLY MATURING PIGEONPEA GENOTYPES

The floral abscission patterns of five early maturing pigeonpea genotypes; ICPL 146 1985HK, ICPL 87 Isotation (85K), ICPL 85010, ICPL 85024 and ICPL 8304 were studied on field grown plants in Missouri. Individual plants were bagged with nylon nets at the beginning of flowering, and the buds, flowers and pods were collected weekly and counted. Abscission began after anthesis and was excessive throughout most of the flowering period. The number of open flowers which abscised was much greater than that of buds or immature pods. The maximum number of weekly abscission of flowers per plant was 470 for ICPL 146 1985HK. Low night temperature below 10°C enhanced abscission of buds, flowers and immature pods in pigeonpea.

Effects of Alternating Night Temperature and Cytokinin Application on the Activity of Enzymes of Sucrose Metabolism in Leaves, Young Shoots and Petals of Roses

The purpose of this report is to compare the activities of SPS, SS and AI in different organs of rose plants grown at alternating temperature to the average activity of these enzymes in plants growns at the constant low and hight night temperatures rather to grow plants at constant temperature of 15°C

Translocation of 14C, carbohydrate content and activity of the enzymes of sucrose metabolism in rose petals temperatures

Both export of 14C from the source leaves of roses (Rosa×hybrida cv. Golden Times) and import of 14C to the petals were reduced by plant exposure to low night temperature. However, the import was affected to a greater extent than the export. During all stages of flower bud development the concentration of reducing sugars in petals of roses grown at reduced night temperature was lower than in petals of plants grown at higher night temperature. There was no significant difference in starch content in response to the night temperature, and the content of starch decreased toward complete flower bud opening. The concentration of sucrose in flowers at the low night temperature remained low during all stages of flower bud development, while at the high night temperature the concentration of sucrose increased during flower bud development, reaching a peak at the stage when petals start to unfold. At both temperatures the concentration of sucrose declined at complete flower opening. The activity of sucrose synthase (EC 2.4.1.14) was inhibited by low temperature in young rose shoots more than in the petals, while the activity of acid invertase (EC 3.2.1.26) was affected similarly in both tissues by the temperature treatments.

The growth and nitrogen economy of rice under sprinkler and flood irrigation in South East Australia

The agronomic implications of growing rice under sprinkler irrigation on a duplex soil in inland south east Australia were examined by comparing 3 sprinkler irrigation regimes applied once, twice and three times a week (S1W, S2W and S3W) with continuous flood irrigation (CF). Each sprinkler irrigation treatment was managed to replace evaporative loss since the previous irrigation. Each irrigation main plot was split into subplots receiving 3 levels of nitrogen (N) fertilizer −0, 80 or 120 kg N ha−1 (0N, 80N and 120N). Grain yield on all sprinkler-irrigated treatments was reduced by 50% or more when compared with CF. There was a slight decline in grain yield with lower frequency of sprinkler irrigation. The main factors contributing to the lower yields were reductions in the number of spikelets per panicle and in floret fertility. Panicle density was not significantly influenced by the irrigation treatments. Sprinkler irrigation delayed anthesis by at least 8 days, and the duration of anthesis was extended by 5 to 7 days. The lower yields under sprinkler irrigation did not appear to be due to greater N deficiency and it is uncertain whether any or all irrigation treatments suffered from P deficiency. Irrigation treatment had little effect on plant N concentration, but P concentration in the plant tops was reduced by sprinkler irrigation during the vegetative and reproductive stages. Low night temperatures throughout the reproductive phase reduced floret fertility, but all irrigation treatments at the same N rate (except SlW/120N) were affected to a similar extent. Water stress, as evidenced by leaf rolling in response to high evapotranspiration rates in this semi-arid environment, was considered to be the main factor contributing to the decline in yield on the sprinkler-irrigated treatments. The irrigation and N rate treatments did not interact significantly in their effect on any important parameter measured. Increasing the rate of applied N from 0 to 80 kg N ha−1 increased yield by about 1 t ha−1 by producing more panicles, but 120N was of no further benefit and was associated with increased floret sterility. Nitrogen fertilizer increased both the N uptake and N concentration in the plant material. We conclude that sprinkler irrigation for rice production is unlikely to be a viable strategy for water management on duplex soils in inland south east Australia. Conventional dry-seeded culture with permanent flood delayed until panicle initiation is probably a preferable alternative to sprinkler irrigation for increasing water-use efficiency.

Cold‐acclimation of Hibiscus rosa‐sinensis L. and Hibiscus syriacus L. in natural and controlled environments

Abstract Seasonal cold‐acclimation patterns and the effects of photoperiod and temperature on cold‐hardiness of Hibiscus rosa‐sinensis L. and Hibiscus syriacus L. were determined. Field‐grown H. rosasinensis consistently failed to survive freezing at ‐ 2°C. Two genotypes of field‐ and container‐grown H. syriacus initiated cold‐acclimation in mid September, in response to decreasing daylength, and continued to an ultimate midwinter hardiness level of ‐ 27°C in early February. Controlled environment experiments using combinations of short days (SD) and cool day/night temperatures were unable to induce even minimal cold acclimation of H. rosasinensis. In controlled environments, H. syriacus attained a moderate amount of cold tolerance at warm temperatures and long days (LD). Low night temperature combined with LD, warm day produced the same degree of cold‐acclimation as the SD treatments. While not essential, SD enhanced H. syriacus cold‐acclimation in controlled environments. A ‐ 5°C frost treatment of intact plants did not enhance cold‐hardiness of H. syriacus.

Soluble Sugars as the Carbohydrate Reserve for CAM in Pineapple Leaves

Neutral ethanol-soluble sugar pools serve as carbohydrate reserves for Crassulacean acid metabolism (CAM) in pineapple (Ananas comosus (L.) Merr.) leaves. Levels of neutral soluble sugars and glucans fluctuated reciprocally with concentrations of malic acid. Hexose loss from neutral soluble-sugar pools was sufficient to account for malic acid accumulation with about 95% of the required hexose accounted for by turnover of fructose and glucose pools. Hexose loss from starch or starch plus lower molecular weight glucan pools was insufficient to account for nocturnal accumulation of malic acid. The apparent maximum catalytic capacity of pyrophosphate:6-phosphofructokinase (PPi-PFK) at 15 degrees C was about 16 times higher than the mean maximum rate of glycolysis that occurred to support malic acid accumulation in pineapple leaves at night and 12 times higher than the mean maximum rate of hexose turnover from all carbohydrate pools. The apparent maximum catalytic capacity of ATP-PFK at 15 degrees C was about 70% of the activity required to account for the mean maximal rate of hexose turnover from all carbohydrate pools if turnover were completely via glycolysis, and marginally sufficient to account for mean maximal rates of acidification. Therefore, at low night temperatures conducive to CAM and under subsaturating substrate concentrations, PPi-PFK activity, but not ATP-PFK activity, would be sufficient to support the rate of glycolytic carbohydrate processing required for acid accumulation. These data for pineapple establish that there are at least two types of CAM plants with respect to the nature of the carbohydrate reserve utilized to support nighttime CO(2) accumulation. The data further indicate that the glycolytic carbohydrate processing that supports acidification proceeds in different subcellular compartments in plants utilizing different carbohydrate reserves.

Seasonal and genetic variation in frost hardiness of Eucalyptusdelegatensis

Seasonal variation in frost hardiness of a range of provenances of Eucalyptusdelegatensis R.T. Bak. was examined in provenance trials at Tarraleah and Myrtle Bank, Tasmania, using a technique based upon the electrical conductivity of diffusate. Maximum hardiness was recorded in July and August, and seasonal variation reached 4.6 °C for individual provenances. The extreme minimum temperature recorded in 1983 was lower than in 1984. Corresponding to this difference the measured level of maximum hardiness was substantially greater in 1983 than in 1984. Substantial differences in frost hardiness occurred between provenances, the differences in mean lethal temperature between provenances being greatest (2.7 °C) when trees were hardened. These differences are sufficient to cause large differences in levels of survival and frost damage at Tarraleah. The Myrtle Bank site experienced less severe temperatures than the Tarraleah site, consequently provenances were found to develop substantially less frost hardiness. However, rankings of provenances were the same at both sites, suggesting that it may be possible to select frost-resistant provenances for Tasmania on the basis of a single test site. However, tests at maritime sites may not serve to indicate rankings for continental climates because the rankings determined in the Tasmanian trials differed markedly from rankings made by other workers at Pilot Hill in New South Wales. Studies with seedlings grown in controlled environments indicated that the rate of frost hardening in E. delegatensis (0.07°C/day) was slow compared with that of many northern hemisphere species but similar to rates reported for some other species of eucalypts. The rate of dehardening was at least twice as rapid as the rate of hardening. The results are consistent with the view that the frost hardiness of eucalypts is determined by both duration and severity of low night temperatures over the preceding 1 or 2 months.