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1.
Exposure to high temperatures (heat stress) causes reduced yield in tomatoes (Lycopersicon esculentum), mainly by affecting male gametophyte development. Two experiments were conducted where several tomato cultivars were grown under heat stress, in growth chambers (day/night temperatures of 31/25 °C) or in greenhouses (day/night temperatures of 32/26 °C), or under control (day/night temperatures of 28/22 °C) conditions. In heat-sensitive cultivars, heat stress caused a reduction in the number of pollen grains, impaired their viability and germinability, caused reduced fruit set and markedly reduced the numbers of seeds per fruit. In the heat-tolerant cultivars, however, the number and quality of pollen grains, the number of fruits and the number of seeds per fruit were less affected by high temperatures. In all the heat-sensitive cultivars, the heat-stress conditions caused a marked reduction in starch concentration in the developing pollen grains at 3 days before anthesis, and a parallel decrease in the total soluble sugar concentration in the mature pollen, whereas in the four heat-tolerant cultivars tested, starch accumulation at 3 days before anthesis and soluble sugar concentration at anthesis were not affected by heat stress. These results indicate that the carbohydrate content of developing and mature tomato pollen grains may be an important factor in determining pollen quality, and suggest that heat-tolerant cultivars have a mechanism for maintaining the appropriate carbohydrate content under heat stress.  相似文献   

2.
The effects of mean daily temperature (MDT) and mean photosynthetic daily light integral (MDLI) on flowering during the finish stage of two petunia (Petunia × hybrida) cultivars were quantified. Petunia ‘Easy Wave Coral Reef’ and ‘Wave Purple’ were grown in glass-glazed greenhouses at 14–23 °C or 14–26 °C and under 4–19 mol m−2 d−1 with a 16-h photoperiod. The flower developmental rate was predicted using a model that included a linear MDT function with a base temperature multiplied by an exponential MDLI saturation function. The flower developmental rate increased and time to flower decreased as MDT increased within the temperature range studied. For example, under a MDLI of 12 mol m−2 d−1, as MDT increased from 14 to 23 °C, time to flower of ‘Easy Wave Coral Reef’ and ‘Wave Purple’ decreased from 51 to 22 d and 62 to 30 d, respectively. Flower developmental rate increased as MDLI increased until saturation at 14.1–14.4 mol m−2 d−1. Nonlinear models were generated for effects of MDT and MDLI on flower bud number and plant height at flowering. The number of flower buds at flowering increased as MDT decreased and MDLI increased. For example, at an MDT of 14 °C with 18 mol m−2 d−1, plants had 2.5–2.9 times more flower buds than those grown at 23 °C and 4 mol m−2 d−1. Models were validated with an independent data set, and the predicted time to flower, flower bud number, and plant height were within ±7 d, ±20 flowers, and ±4 cm, respectively, for 96–100%, 62–87%, and 93–100% of the observations, respectively. The models could be used during greenhouse crop production to improve scheduling and predict plant quality of these petunia cultivars.  相似文献   

3.
Incidence of parthenocarpic fruit, undeveloped flowers and flower abortion in tomato plants (Lycopersicon esculentum Mill.) were compared under optimal temperature (OT, 28/22°C day/night) and chronic, mild high temperature conditions (HT, 32/26°C). Seeded fruits were found only under OT conditions, where 37±9% of all flowers developed into seeded fruit. However, flower aborted was also higher under OT, with an additional 24±7% of flowers aborted under optimal temperature conditions, compared to only 4±1% of flowers aborted under HT conditions. Under HT, most flowers (53±8%) developed into parthenocarpic fruit, and the remainder (43±7%) stayed on the plant as undeveloped flowers. A slow transition of undeveloped flowers to parthenocarpic fruit was also observed under HT. Factors determining whether flowers abort, develop parthenocarpically, remain on the plant without developing further, or develop into seeded fruit were discussed in relation to carbohydrate availability and the presence of seeded fruit on the vine.  相似文献   

4.
A tomato (Solanum lycopersicum L.) crop was grown in four greenhouses during the dry season 2005/06 in Central Thailand. Sidewalls and roof vents of two greenhouses were covered with nets and these greenhouses were mechanically ventilated when air temperature exceeded 30 °C (NET). The other two greenhouses were covered with polyethylene film and equipped with a fan and pad cooling system (EVAP). Overall mean air temperature was significantly reduced by 2.6 and 3.2 °C (day) and 1.2 and 2.3 °C (night) in EVAP as compared to NET and outside air, respectively. Temperature maxima in EVAP averaged about 4 °C lower than in NET and outside. The relative humidity was around 20 and 30% (day) and 10 and 15% (night) higher in EVAP than in NET or outside, respectively. Vapour pressure deficit averaged 0.25 kPa in EVAP, 1.03 kPa in NET and 1.48 kPa outside. The crop water-consumption was significantly lower in EVAP (1.2) than in NET (1.8 L plant−1 day−1), which is ascribed to reduced transpiration in EVAP. Total fruit yield was similar in NET (6.4 kg plant−1) and EVAP (6.3 kg plant−1). The quantity of undersized (mostly parthenocarpic) and blossom-end rot (BER)-affected fruits was reduced in EVAP. However, the proportion of marketable yield was significantly higher in NET (4.5 kg plant−1) than in EVAP (3.8 kg plant−1), owing largely to an increased incidence of fruit cracking (FC) in EVAP. Higher FC but lower BER incidence coincided with higher fresh weight and Ca concentration in the fruits in EVAP. It is concluded that in regions with high atmospheric relative humidity evaporative cooling without technical modifications allowing dehumidification will not improve protected tomato production.  相似文献   

5.
One-year-old scale bulblets of Lilium longiflorum Thunb. ‘Nellie White’ (Easter lily) were grown under a combination of six constant day/night temperature regimes and five N–P–K nutrient treatments under short days for 107 d (growing period 1 or GP-1) to compare the effects on growth and development and bulb production. Results during GP-1 were as follows: failure of bulblets to produce a shoot (“no-shows”) was found at high temperatures (30/26 and 26/22 °C) and not influenced by the nutrient treatments. Flower bud abortion was observed in the minus-N, minus-P, and minus-N–P–K treatments at high temperatures (30/26 or 26/22 °C), but not observed at any temperatures in the complete and minus-K treatments. The loss of bulb fresh weight in minus-N treated bulblets was less than in the other treatments resulting in less root and shoot growth in the minus-N treatment. At the intermediate temperatures where growth was highest, omission of N, P, K, or all three resulted in losses in stem bulb fresh weight, stem plus leaf fresh weight, number of flowers, and stem root fresh weight. Omission of N, P, or all three nutrients resulted in lowest basal root fresh weight. Bulb N and K concentrations were lowest in plants grown with complete nutrient solution at the two coldest temperature regimes (14/10 and 10/6 °C). Bulb P concentration was lowest at the three coldest (18/14, 14/10 and 10/6 °C) and the warmest (30/26 °C) temperature regimes. Stem length was shorter when P was omitted. Omission of any of the three nutrients resulted in lower concentrations of the other nutrients. The one exception was where low K did not affect N concentration. In the second phase of the experiment, plants grown at 18/14 °C and irrigated with the complete nutrient solution for 107 d (GP-1) were continued at this day/night temperature regime and five N–P–K nutrient treatments for another 89 d under long days (growing period 2 or GP-2). Results during GP-2 were as follows. Basal bulb yield was not impacted by omission of N, P, or K, or all three. Of all growth measurements, only stem plus leaf fresh weight was lower and only when all three nutrients (minus-N–P–K) were omitted. At the end of GP-2, basal bulb concentrations of N and P did not differ from the concentrations in bulbs at the beginning of GP-1; however, K concentration was lower at the end of GP-2. Omission of N or P further resulted in lower bulb K concentration, suggesting that a moderate supply of N, P, and K be applied during GP-2 since an additional year of bulb production is needed to produce forcing-sized bulbs.  相似文献   

6.
Reducing energy use in greenhouses contributes to the profitability of horticulture. Important energy savings can be realized through the use of temperature integration. However, such a greenhouse heating strategy is only acceptable for commercial purposes if there are no adverse effects on plant growth and quality. During this 3-month study, Hedera helix ‘Green Ripple’ and H. helix ‘Shamrock’ were subjected to a day/night temperature regime of 20/20 °C (control) and two treatments with temperature integration over 24 h and 4 d, respectively, based on a DIF of 13.5 °C, maintaining the average temperature at the same level of the control. Temperature treatments resulted in a promotion of stem elongation. After 3 months, shoot length rose up to maximum 37.3% when temperature integration was applied. However, temperature integration reduced total dry weight and particularly root dry weight was negatively affected. In addition, assessments of relative growth rate, shoot extension rate, specific leaf area, total leaf area and pigment concentrations were performed and it was concluded that dynamic temperature regimes with longer integration periods support commercial production of English ivy.  相似文献   

7.
The effect of preharvest fruit temperature on the relationships between development of watercore and ethylene evolution, flesh firmness, membrane permeability and sorbitol level in two watercore-susceptible apple (Malus domestica Borkh.) cultivars, ‘Himekami' and ‘Fuji', was investigated at ambient or modified temperatures of 10, 15 or 25°C. Watercore occurrence was completely inhibited at 25°C in both cultivars whereas fruit subjected to 10 or 15°C exhibited significantly higher watercore ratings after two or three weeks of the treatment than those at 25°C and ambient temperatures. Ethylene production of ‘Himekami' apples increased at 25°C and ambient temperature but not at 15°C. Ethylene production was not affected by treatment in ‘Fuji' apples. Flesh firmness of ‘Himekami' tended to maintain a higher level at 15°C than at 25°C, while there was no clear difference among the treatments in ‘Fuji'. The rate of potassium (K) ion elution from the flesh tissues of either cultivar was not affected by fruit temperature treatment. Sorbitol content at 15°C maintained significantly higher level than that at 25°C during the treatment in ‘Himekami' apples although no sorbitol difference was observed among the temperature treatments in ‘Fuji' apples.  相似文献   

8.
The influence of day and night temperatures in the range of 10–17°C on the vegetative growth under long days of 17 year-round cultivars of chrysanthemum was studied. The after-effect of the temperature regime on the time of flowering at 17°C under short days was also recorded.A decrease of the day or night temperature reduced growth, but the effect of the day temperature was much stronger than that of the night temperature. The temperature during the vegetative period had hardly any effect on the time of flowering at 17°C.The consequences for production and breeding are discussed.  相似文献   

9.
Energy utilization for heating is one of the most expensive greenhouse climate control operations. The temperature set-point is determined by many interrelated environmental, physiological, and economic factors but is fundamentally driven by the required growth rate of the plant or crop for quality and profitability. Temperatures are maintained to maximize production and affect timing of harvest of greenhouse-grown crops. In general, winter greenhouse environments for most cut-flower roses are heated to a target temperature of 16–18 °C. For rose, such temperature targets are based on grower experience along with horticultural research and should be considered a compromise across all factors. In the current research we studied the concept of “potential growth rate” (PGR), based on a thermodynamic growth model and how PGR relates to the typical temperature recommendation (TTR) for set-points for greenhouse heating and cooling in commercial horticultural production. PGR of specific growing organs (leaves, shoot tips, roots, etc) can be deduced using calorespirometric measurements in relation to various environmental factors such as temperature effect on biomass production. This research consisted of two facets: (1) determination of cultivar-specific alternate TTRs based on calorimetric PGR measurement and then (2) testing these TTRs in greenhouse rose flower production. The results of this study suggested that TTRs for the cultivar ‘Kardinal’ can be lowered at the time of bud emergence, when this cultivar can tolerate a lower temperature. Also, since the cultivar ‘Milva’ can tolerate lower temperature at time of leaflet unfolding, the current TTR can be adjusted to reflect this. We investigated a set of alternate TTRs by growing rose plants on movable carts and shifting them to various pre-determined night temperature conditions. During the relevant growing stages, half of the plants were given a cold night temperature (14 °C) treatment, while control plants were left in the normal greenhouse temperature (18 °C). This procedure was repeated for three flushes of flowering rose shoots. Flower shoots were counted and weighed (fresh and dry); shoot length was measured several times per week. It was found that the predictions were valid and (with one exception) no significant effect on the number of flowers, their quality or biomass was caused by this procedure. The implication of this work is that heating cost can be reduced for some rose cultivars by allowing night temperatures to be lower than the typical recommendations for those cultivars that show high metabolic activity at such cooler conditions.  相似文献   

10.
Summary

The cracking of bell pepper fruit is one of the main physiological disorders that reduce marketable yield. Understanding the environmental and endogenous factors that influence this disorder may help to reduce its severity. Plants grown in three greenhouses were subjected to differing potential transpiration (Tp) at night, with identical daytime Tp. Measurements included climatic variables in the greenhouses, soil water content, sap flow, transpiration, leaf temperature, surface and internal fruit temperatures, fruit and stem diameters, stomatal conductance, and leaf area. The results show that at night pepper plants transpired at a rate proportional to the vapour pressure difference (leaves to air; VDPla) in the respective greenhouses. The percentage of cracked fruits was highest in the greenhouse with the lowest night vapour pressure deficit (VPD) and lowest in the greenhouse with the highest VPD. Both increased direct radiation reaching the fruit surface and decreased soil water content reduced the growth rate of the fruit. Direct radiation and the temperature of the fruit inner space were well correlated with diurnal expansion and shrinkage of the fruit. The fruits with the higher expansion-shrinkage amplitude had more severe cracking symptoms. Decreased soil water potential counteracted the negative effect of direct radiation. These results indicate that the water status of the fruit is a key factor in determining the severity of fruit cracking. The implications of these results for greenhouse management in pepper production are discussed.  相似文献   

11.
The rat’s tail radish (Raphanus sativus cv. “Pakki-hood”), cultivated in the northern part of Thailand, does not require low temperature for flower-bud initiation and shows high germinability even at low temperature. To analyze its characteristic temperature response, seedlings were subjected to a 3 day-chilling treatment at 0°C after a series of incubations for germination at 26°C which ranged from 3 h to 4 days. The chilling treatment after an initial stage (3 h to less than 2 days) of incubation at 26°C did not significantly affect the hypocotyl regrowth, but the same treatment after a more than 2-day incubation at 26°C reduced subsequent hypocotyl growth of plants. 1-aminocyclopropane-1-carboxylic acid (ACC)-dependent ethylene-forming activity was also reduced by the chilling treatment after 2–4-day incubation at 26°C. Electrolyte leakage from tissues of seedlings in the chilling treatment was increased in proportion to the length of the incubation at 26°C, indicating severe damage of chilling to plasma membranes after a longer incubation. We found a transition of chilling-sensitivity at 2 days in the incubation period for germinating seeds of Pakki-hood. Seedlings of Pakki-hood chilled earlier than the transition are relatively unaffected in their subsequent growth, but the seedlings become sensitive to chilling after the transition.  相似文献   

12.
Stock plants were grown in a glasshouse under standard growing conditions. Single-node leafbud cuttings were excised and numbered according to the position on the stock plant. Rooting took place at basal temperatures of 17,20 or 23°C and at different durations at 17 or 20°C followed by 23°C. The rooting period lasted 9 weeks.

The temperature of 17°C for 9 weeks completely suppressed root formation. A temperature of 20°C was decisive for root formation. The optimal rooting temperature was higher than 23°C. Temperature treatments of 17 or 20°C for 2–4 weeks only suppressed rooting slightly compared with the 23°C treatment. Cutting position on the stock plant affected the number of roots formed per cutting but not the rooting percentage. Best rooting was observed in cuttings from the middle part of the stock plant.

Axillary bud break was accelerated with increasing rooting temperature and decreasing duration of the lower temperatures. With increasing cutting position number (numbered from top to base), axillary bud break was considerably delayed.

Temperature treatments which delayed root formation also delayed axillary bud break. On the other hand, the cutting position on the stock plant, which had only a minor effect on the speed of root formation, had a pronounced effect on the speed of axillary bud break.  相似文献   


13.
The temperature induced changes in chlorophyll fluorescence induction parameters (F0, Fm, Fv and their ratios) measured by a PEA analyzer were used to screen for heat-tolerance 12 cultivars and lines of common bean (Phaseolus vulgaris L.) available in the germplasm collections of Maritsa Vegetable Crops Research Institute, Plovdiv, and Institute of Plant Genetic Resources, Sadovo, Bulgaria. The experiments were carried out in a selection field of Maritsa Institute. The measurements were made on six different dates during the bean reproductive period (in June–July) when the temperatures were approximately 26 °C in the morning to and 42 °C at noon. Two lines, known earlier as heat-tolerant were used as controls.  相似文献   

14.
兰州地区引种的美国扁桃的越冬伤害与临界致死低温   总被引：17，自引：1，他引：17  
 通过田间越冬指数调查、组织变褐法和电导法配合Logistic 方程求拐点温度的方法, 对7 个从美国引入的扁桃品种的抗寒性进行评价。结果表明: 扁桃幼树1 年生休眠枝的低温半致死温度( LT50) 为- 18. 0 ~ - 24. 5; 其中 Butte和 Padre的抗寒性较强, 半致死温度约为- 24. 5; Nonpareil、Price! 和 Monterey! 的抗寒性中等, 半致死温度约为- 20. 9; Ne Plus! 和 Sonora! 的抗寒性较弱,半致死温度约为- 18. 3。  相似文献   

15.
The effect of night temperature on short day (SD) floral induction has been studied in three June-bearing strawberry cultivars of different geographic origin and compared with yield performance in the cool Nordic environment. At the optimum day temperature of 18 °C, the SD flowering response of the cultivars ‘Florence’ and ‘Korona’ increased significantly with increasing night temperature from 9 to 18 °C, while an optimum was reached at 15 °C in the cultivar ‘Frida’ that is selected under cool-environment conditions in Norway. Also, while saturated flowering response was obtained with 3 weeks of SD treatment at all temperatures in ‘Frida’, several plants of ‘Florence’ and ‘Korona’ failed to initiate flowers at 9 °C night temperature even with 5 weeks of SD. The effect of extended SD period was particularly pronounced in ‘Florence’. The slow SD floral induction response of ‘Florence’ was associated with a 2 week delay of anthesis in subsequent long day (LD) conditions at 21 °C. Yield performance of the same cultivars during 2 years under field conditions at Nes Hedmark and in North Norway also demonstrated that the yield potential of ‘Florence’ was not realized under the climatic conditions prevailing at these locations. In both years the yields varied significantly among the cultivars, ‘Frida’ having the highest yields followed by ‘Korona’, with ‘Florence’ far below. It is concluded that, in the Nordic environment, autumn (September) night temperatures are obviously sub-optimal for yield performance of some June-bearing strawberry cultivars, and that this effect is mediated by autumn temperature effects on flower initiation responses.  相似文献   

16.
Summary

The effects of a pre-sowing seed treatment with a temperature drop (i.e., seed thermo-priming) on the growth and development of two popular bedding plant species, Tagetes patula nana L. (marigold) and Viola wittrockiana Gams. (pansy), were studied. A temperature drop from 22°C to 10°C was applied for 2 h each day during seed germination, over the 6 d before sowing. This seed priming increased plant dry mass, hastened flowering in both species, and increased flower numbers in marigold, but not in pansy. An involvement of certain phytochromes in these temperature-dependent effects on time-to-flowering is suggested.  相似文献   

17.
The responses of January-sown cucumber cvs Farbio and Sandra to day and night temperature during the early post-planting stage (late February to mid-April) were examined in a glasshouse experiment. Three day temperatures (15°, 20° and 25°C) were combined factorially with three night temperatures (10°, 15° and 20°C). Comparisons were also made between two temperature regimes (21°C day: 19°C night and 24°C day: 17°C night) applied during the pre-planting stage (late January to late February) and between two mainstem cropping methods (restriction or retention of mainstem fruits). In the pre-planting stage the 24°C day: 17°C night temperature combination produced plants which were taller, heavier and leafier than those grown at 21°C day: 19°C night. During the first 12 weeks of harvesting the larger plants produced significantly more fruit and higher gross monetary returns than did their smaller counterparts. The difference then diminished and after 20 weeks of harvesting plants from the two pre-planting temperature treatments had produced similar weights of marketable fruit of equivalent value. In the early post-planting period increases in total leaf area and stem length were closely correlated with 24-h mean temperature. Earliness (first harvest) and total weight of fruit after four weeks of harvesting were also linearly related to mean post-planting temperature. Raising the 24-h mean air temperature (within the range 15.2° to 22.6°C) by 1°C during the early post-planting stage increased early (4 week) yield by 0.82 kg m-2 and total (20 week) yield by 1.17 kg m-2. There was no effect of day/night temperature amplitude. After 20 weeks of harvest, gross monetary returns and profitability were generally highest when mean temperature in the early post-planting period was high and fell progressively with reduced mean temperature. Restricting stem fruits to oné per leaf node produced no significant difference in either the yield or quality of fruit from plants of any of the temperature treatments. The results are discussed from physiological and practical viewpoints and a cost-benefit comparison of temperature treatments is presented.  相似文献   

18.
Lobelia×speciosa Sweet ‘Compliment Scarlet' was grown under a range of photoperiods and low temperature treatments to determine their effects on flowering. In the first experiment, plants were held at 5°C for 0 or 15 weeks, then grown at 20°C under the following photoperiods: 10, 12, 14, 16, or 24 h of continual light or 9 h with a 4 h night interruption (NI). Non-cooled ‘Compliment Scarlet' flowered as a qualitative long-day plant (LDP) with a minimum flowering photoperiod of 14 h. Following cold, flowering was quantitative with respect to photoperiod, until ≈14.2 h, when the calculated rate of progress toward flowering reached a plateau. In cooled plants, node number below the inflorescence decreased from 27 to 16 as the photoperiod increased from 10 to 24 h. Cooled plants developed 61–149% more flowers and were ≥17% taller than non-cooled ones under the same photoperiod. To determine the cold duration required for flowering under short days (SD), plants were held at 0, 3, 6, 9, 12, or 15 weeks at 5°C then grown at 20°C under SD (9 h photoperiod) or long days (9 h photoperiod with a 4 h NI). Under SD, few plants flowered after ≤6 weeks of cold. As cold treatment increased from 9 to 15 weeks, flowering percentage increased, time to flower decreased from 93 to 64 days, and node count decreased from 24 to 13. Cold treatment did not affect flowering percentage or time under NI, but plants always had more flowers and were taller than reproductive ones under 9 h day lengths. Thus, ‘Compliment Scarlet', is a qualitative LDP, but an extended cold treatment can partially substitute for the long day (LD) photoperiodic requirement.  相似文献   

19.
Summary

The effects of suboptimal low temperature were investigated on an array of yield, fruit appearance and fruit quality characters in 23 cultivars of melon, Cucumis melo L. The cultivars were grown in two temperature regimes: (I) a heated greenhouse (T1) with temperatures similar to those used in commercial cultivation in the winter in Israel; and (ii) an unheated greenhouse (T2) that had significantly lower night temperatures than T1. Significant differences were found among the cultivars in all characters. Plants from T2 showed an extended fruiting period, more fruits and higher total yield but smaller and lighter fruits than in T1. Fruits from T2 also had significantly more netting and higher amounts of total soluble sugars (TSS), sucrose and fructose than fruits from T1. Hybrid cultivars showed significantly higher electrical conductivity (EC), pH, acidity, TSS, sucrose, fructose and total sugars than open pollinated cultivars. Three trends were found among the characters in respect to the performance of the cultivars between T1 and T2: (a) most cultivars had significantly higher amounts in T2 than T1 (fruit/plant, yield/plant and fructose); (b) only cultivars with amounts below the pooled mean in T1 had higher amounts in T2 (percent dry weight, sucrose, TSS and total sugars); (c) no trend was found between T1 and T2 (mean fruit weight, pH, EC, glucose). Suboptimal low temperatures, when used appropriately, can aid in improving fruit quality.  相似文献   

20.
低温胁迫下佛手半致死温度测定和抗寒性分析   总被引：10，自引：0，他引：10  
 以‘青皮’和‘矮化’佛手(Citrus medica var. sarcodactylis Swingle)为试材,测定不同低温下处理24 h后,叶片的电解质外渗率(REC),计算半致死温度(LT50);在半致死温度下设置不同处理时间,测定REC、超氧化歧化酶(SOD)活性、游离脯氨酸(Pro)和丙二醛(MDA)含量,进行抗寒性分析。结果表明：佛手REC随温度降低及处理时间延长呈“S”形上升, LT50在-4~ -5℃之间;在LT50下,随着处理时间的延长SOD活性呈先上升后下降的趋势, Pro和MDA含量逐渐上升;12~ 24 h为佛手在LT50下冷害发生的临界时间。  相似文献   

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