首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Summary

Shoot growth attributes, leaf anatomical changes and net photosynthetic rates were determined in young coffee plants fertilized at high and low levels and subjected to shade or full sunlight. High nitrogen supply increased plant height irrespective of the light level imposed during growth, and promoted a larger leaf area in plants of the shade treatment. Specific leaf weight was 15% higher in plants grown in full sunlight than in shaded plants, at both nitrogen levels. The number of leaves developed on the orthotropic stem increased significantly under full irradiance and high nitrogen availability. Leaves were 11% thicker ih unshaded plants than in shaded ones, because of the increased size of the palisade and spongy parenchyma tissues. More thylakoids per granum and more grana per chloroplast were observed in shade-grown plants, mainly in those given high nitrogen treatment. Total nitrogen content expressed on a leaf-area basis was higher in sun plants supplemented with nitrogen, whereas chlorophyll a and b and protochlorophyll contents increased in shade-grown plants. Net photosynthetic rate in high nitrogen plants reached 7.19 µmol CO2 m?2 s?1 in the full irradiance treatment, and 5.46 µmol CO2 m?2 s?1 in shaded plants. Maximum net photosynthetic rates in the low nitrogen plants were 5.28 and 4.90 µmol CO2 m?2 s?1 in sun and shade plants, respectively. Increased photosynthetic light saturation was observed in high irradiance plants (628 µmol m?2 s?1) relative to shade plants (359 µmol m?2 s?1) in the high nitrogen treatment. The same pattern was observed in low nitrogen plants. The apparent quantum yield of shade acclimated plants was 14% higher than in those grown in full sunlight. Our results indicate that coffee may be classified as a facultative shade species, exhibiting features of sun adapted plants coupled with shade acclimation attributes, this fairly high adaptive capacity to shade:sun transition being strongly influenced by the level of nitrogen nutrition given to the plants.  相似文献   

2.
The plant growth regulator CycocelTM [(2-chloroethyl)trimethylammonium chloride] can be used to produce drought tolerance in grapevine (Vitis vinifera L.) due to a reduction in the ratio between vegetative growth and fruit production. To evaluate the physiological responses of two grapevine cultivars to drought and CycocelTM treatment, a factorial experiment was conducted in a greenhouse. The factors included irrigation frequency (at 5-, 10-, or 15-day intervals corresponding to no, mild, or severe drought stress), CycocelTM concentration (0, 500, or 1000 mg l1), and cultivar (‘Rasheh’ or ‘Bidane-Sefid’). Stomatal conductance (gs) the net rate of CO2 assimilation (Anet), the rate of transpiration (Tr), and chlorophyll a and b concentrations decreased in plants exposed to mild or severe water-deficit stress, whereas carotenoid, proline, and total soluble sugar concentrations increased compared to plants with no drought stress. The relative water content (RWC) of leaves declined only under severe drought stress. A reduction in intercellular CO2 concentrations (Ci) occurred under mild drought stress; however, under severe drought stress, Ci values increased. Under mild drought stress, the reduction in the net rate of photosynthesis was related to stomatal closure, whereas under severe drought stress, non-stomatal factors were dominant. Water-use efficiency (WUE) improved under mild drought stress relative to non-stressed plants, but under severe drought, it declined. Foliar applications of CycocelTM resulted in increased Anet, gs, Tr, and WUE values, as well as proline and soluble sugar concentrations. ‘Rasheh’ was more tolerant to drought stress than was ‘Bidane-Sefid’. Foliar applications of CycocelTM, particularly at 1000 mg l1, mitigated the negative effects of drought stress by increasing Anet, WUE, RWC, compatible solute concentrations, such as proline, soluble sugar, and chlorophyll a and b concentrations.  相似文献   

3.
Summary

The effects of leaf segment, leaf position on the plant, leaf age and photosynthetic photon flux density (PPFD) at the leaf surface were examined on leaf gas exchange of cv. Williams banana. All measurements were made on irrigated plants at the end of the dry season (September to November) over three years in Kununurra, WA, (Lat 16×S) a hot, arid region of North Western Australia. Net photosynthesis (Pn) did not differ between the segments on the leaf except when they received different PPFD. Pn reached a maximum of 20 to 25 μmol CO2 m–2s–1,9 d after the leaf had unrolled, that is when another new leaf had emerged and the measured leaf was in the second leaf position. Leaf chlorophyll concentration stabilized 7 d after unrolling but then increased slowly with time. The reduced rates of leaf gas exchange of older leaves are most likely a result of shading by younger leaves. The highest measured PPFD of 1800 (junol quanta m–2s–1 did not saturate Pn. Indeed, in a series of experiments, Pn measured at 1500 μmol quanta m–2s–1, was only 13 to 40% of the calculated maximum Pn at saturated values of PPFD, assuming Pn responds to PPFD in a hyperbolic function. In this study although Pn was lower in older leaves, the calculated internal CO2 concentration did not increase even at high leaf temperatures and leaf-to-air vapour pressure differences. Therefore, the photochemistry of the chloroplasts did not constrain Pn. To compare gas exchange measurements among experimental treatments, care is required as leaf position and environmental effects can greatly influence results. Our data suggest that differences in Pn between treatments should take account of PPFD, especially in this environment where the maximum PPFD measured did not saturate Pn of individual leaves.  相似文献   

4.
Storage of ‘McIntosh’ Apples (Malus domestica Borkh.) in a controlled atmosphere (CA) with very low O2 (1.5% CO2 + 1.0% O2, 2.8°C) retained greater fruit firmness and titratable acids during storage and during subsequent air storage than apples stored in conventional CA (5.0% CO2 + 3.0% O2, 2.8°C). The rate of firmness loss during subsequent 0°C air storage decreased with length of storage in CA. Storage of apples in very low O2 for 40 or 80 days decreased the rate of firmness loss in subsequent 0°C air storage as compared to the rate of firmness loss in conventional CA fruit, but the rate of firmness loss in 0°C air storage subsequent to 160 or 320 days of conventional CA was significantly less than the loss in similar fruit stored in very low O2 atmospheres.A modified atmosphere with 1.0% O2 decreased the rate of C2H4 accumulation in storage, and fruit production of both C2H4 and CO2 after storage opening in comparison with similar fruit in conventional CA. The accumulation of C2H4 in storage chambers was increased with increasing O2 levels, but the rate of increase depended upon the CO2 level. C2H4 storage accumulation was stimulated by the presence of CO2 at 0.5% O2, but was suppressed by CO2 when 3.0% O2 was maintained.Retention of fruit firmness and titratable acids in apples stored in 1.5% CO2 + 1.0% O2 were insensitive to very low (0.231 ml l?1) or very high (2440 ml l?1) C2H4 levels in storage. Scrubbing C2H4 (0.304 ml l?1) from chambers held at 5.0% CO2 + 3.0% O2 resulted in significantly firmer fruit after storage, but this effect was not significant after shelf life of 7 days at 20°C.  相似文献   

5.
Summary

The response of photosynthesis of leaves of greenhouse tomato plants to leaf position and vapour pressure deficit (VPD) was studied by modelling the effect of these on leaf conductance to CO2. The study was carried out in Avignon (southern France) on well-irrigated plants during spring and summer seasons, with VPD ranging from 0.7 to 3.4 kPa at midday, while the 24 h mean ranged from 0.6 to 1.8 kPa. Net photosynthesis (Pn) was measured on single leaves placed at three levels defined by the leaf position, and under different CO2 concentrations in the range of 200 to 1100 µmol mol–1. A model for leaf photosynthesis was used to evaluate the leaf conductance to CO2 transfer. The leaf conductance to CO2 transfer was maximum for top level leaves, and decreased with leaf depth in the canopy. Leaf conductance at the upper level was reduced when air VPD exceeded a threshold value of 1 kPa.  相似文献   

6.
With 4 genotypes of tomato, irradiance and CO2-response curves of net photosynthesis were analysed by means of curve fitting. Estimated values of the light compensation point Ic showed small but significant differences between the genotypes, the overall value being in the order of 8 W m?2. The photochemical efficiency (αn) and the maximum net photosynthesis per unit leaf area basis (Pnm) reached the highest values for ‘F6 IVT’ (13.3 μg CO2 J?1 resp. 0.549 mg CO2 m?2 s?1), the lowest value of αn with ‘Bonabel’ (9.9 μg CO2 J?1), and the lowest value of Pnm with ‘PI 114969’ (0.424 mg CO2 m?2 s?1). The CO2-compensation point (Cc) was relatively high (177–245 mg m?3). ‘F6 IVT’ demonstrated the highest value of Cc, the lowest carboxylation efficiency and the highest maximum rate of net photosynthesis. The results clearly demonstrate that the latter genotype requires a much higher external CO2-concentration than the other genotypes in order to exhibit the highest rate of net photosynthesis.  相似文献   

7.
In the daytime, a CO2 depletion of 10–15% and air circulation of less than 0.5 m s−1 often occur in a naturally ventilated greenhouse during a sunny day with high wind speed (3–5 m s−1). We, therefore, investigated the effects of moderate increase of the CO2 concentration above the atmospheric level (500–600 μmol mol−1) and air circulation up to 1.0 m s−1 in a growth chamber on the net photosynthetic and transpiration rates of tomato seedlings as the first step. The average net photosynthetic rates were 2.1, 1.8, and 1.6 times higher in the growth chambers with increased CO2 concentration (500–600 μmol mol−1) and air circulation (1.0 m s−1), increased CO2 concentration, and increased air circulation, respectively, compared with those in the control (no increase in CO2 concentration (200–300 μmol mol−1) or air circulation (0.3 m s−1). The transpiration rate increased with increased air circulation, while it decreased with increased CO2 concentration regardless of air circulation. From the results, we consider that increasing the CO2 concentration and/or air circulation in ventilated greenhouses up to the outside concentration (350–450 μmol mol−1) and 1.0 m s−1, respectively, can significantly increase the net photosynthetic rate of greenhouse plants.  相似文献   

8.
Summary

Avocado fruits were washed with 200 µg l–1 active chlorine, partially ripened to a firmness of about 12.5 ± 0.6 kg cm–2, and sliced. Fruit slices were dipped in 1.0 mg l–1 citric acid and 200 µg l–1 ascorbic acid maintained at 4°–6°C for 2 min, dried with tissue paper and packaged in 0.05 mm or 0.075 mm-thick low density polyethylene (LDPE) at a 1:1 surface area to product weight ratio (cm2 g–1). Sodium chloride (1 g) sealed in 0.075 mm-thick poly-coated paper pouches was included in the packages for moisture absorption. In-package O2 and CO2 concentrations, as well as the ethanol and acetaldehyde concentrations, firmness and lightness (L* value) of the tissue slices were measured during storage for 10 d. The sensory attributes of the modified atmosphere (MA)-packaged slices were compared with fresh fruit slices. In-package O2 concentrations fell from 14.1% to 6.3% and CO2 concentrations rose from 4.7% to 4.9%. Ethanol concentrations increased from 9.0 to 32.1 µg g–1 and acetaldehyde from 1.1 to 3.8 µg g–1 during storage from day-1 to day-10 in the 0.05 mm-thick LDPE with sodium chloride moisture absorbers. In-package concentrations of O2 fell from 10.8% to 3.8% and CO2 rose from 3.8% to 8.1%, while ethanol concentrations increased from 10.0 to 40.4 µg g–1 and acetaldehyde from 1.3 to 4.7 µg g–1 during storage from day-1 to day-10 in the 0.075 mm-thick LDPE with sodium chloride moisture absorbers. The L* value and sensory attributes of avocado slices packaged in 0.05 mm-thick LDPE, with moisture absorbers, were not significantly different from fresh slices, indicating the effectiveness of these MA conditions. Regardless of packaging conditions, avocado slices reached the firmness values of 5.8–6.3 kg cm–2 required for the ‘table-ripe’ stage on day-10 in storage. Therefore, packaging of ‘Booth 7’ avocado slices in 0.05 mm-thick LDPE with sodium chloride as a moisture absorber resulted in a storage-life of 10 d at 8°C and 90 ± 2% RH.  相似文献   

9.
Summary

Experiments were conducted to observe the effect of different concentrations of 1-methylcyclopropene (1-MCP) on the post-harvest life and quality of ‘Allison’ kiwifruit (Actinidia deliciosa). Fruit were treated with 1-MCP at 0.5 µl l–1, 1.0 µl l–1, or 2.0 µl l–1, un-treated fruit served as controls. Each 1-MCP treatment was applied for 24 h at 20°C. After treatment, fruit were transferred to ambient temperature storage (22º ± 4ºC; 65 – 70% relative humidity) for 18 d, during which time observations on various physical, physiological, and biochemical parameters were recorded at 3 d intervals. Our results indicated that 2.0 µl l–1 1-MCP was the most effective treatment to delay softening and ripening in ‘Allison’ kiwifruit, as such fruit showed the lowest mean weight loss (9.8 ± 0.2%), the highest mean fruit firmness value (32.7 ± 0.2 N), and began to ripen only after 12 d in storage, whereas untreated fruit started ripening on day-6 of storage. The activities of fruit softening enzymes such as polygalacturonase (PG; 58.5 ± 0.3 µg galacturonic acid g–1 FW h–1), and lipoxygenase (LOX; 3.96 ± 1.3 µmoles linoleic acid oxidised min–1 g–1 FW h–1) were lower, and total phenolics (TP) contents (24.3 ± 0.3 mg 100 g–1) and anti-oxidant (AOX) activities (12.5 ± 0.03 µmol Trolox g–1 FW h–1) were higher in 1-MCP-treated fruit than in untreated fruit (PG, 98.3 ± 0.5 µg galacturonic acid g–1 FW h–1; LOX, 4.39 ± 1.0 µmoles min–1 g–1 FW h–1; TP, 5.3 ± 0.6 mg 100 g–1; AOX, 4.7 ± 0.02 µmol Trolox g–1 FW h–1, respectively). In addition, 1-MCP-treated fruit exhibited lower rates of respiration (48.3 ± 0.4 ml CO2 kg–1 h–1) and ethylene production (30.2 ± 0.02 µl kg–1 FW h–1) than untreated fruit (58.9 ± 0.6 ml CO2 kg–1 h–1; 38.7 ± 0.04 µl kg–1 FW h–1, respectively). Similarly, 1-MCP-treated fruit had higher titratable acidity (TA; 1.33 ± 0.3%) and ascorbic acid (AA) contents (115.9 ± 2.6 mg 100 g–1 pulp) and lower soluble solids contents (SSC; 8.33º ± 0.2º Brix) than untreated kiwifruit (TA, 1.0 ± 0.2 %; AA, 105.3 ± 2.2 mg 100 g–1 pulp; SSC, 13.7º ± 0.3º Brix, respectively). Thus, 2.0 µl l–1 1-MCP can be used for the post-harvest treatment of ‘Allison’ kiwifruit to enhance its shelf-life and marketability by approx. 6 d.  相似文献   

10.
《Scientia Horticulturae》2005,104(1):11-24
Leaf CO2 assimilation rate, stomatal conductance (gs), internal CO2 concentration (Ci), chlorophyll (a + b) content, specific leaf weight (SLW) and stomatal density were measured during the season, under field conditions, for five major Greek olive cultivars, ‘Koroneiki’, ‘Megaritiki’, ‘Konservolia’, ‘Lianolia Kerkiras’, and ‘Kalamon’, with different morphological and agronomic characteristics and diverse genetic background. Measurements were taken from current-season and 1-year-old leaves, and from fruiting and vegetative shoots, throughout the season, from March to November in years 2001 and 2002. CO2 assimilation rates showed a substantial seasonal variation, similar in all cultivars, with higher values during spring and autumn and lower values during summer and late autumn. Stomatal conductance (gs) followed similar trends to leaf CO2 assimilation rates, increasing from March to July, following by a decrease during August and increasing again in autumn. ‘Koroneiki’ had the highest leaf CO2 assimilation rate and gs values (21 μmol m−2 s−1 and 0.45 mol m−2 s−1, respectively) while ‘Lianolia Kerkiras’ and ‘Kalamon’ showed the lowest leaf CO2 assimilation rate and gs values (13–14 μmol m−2 s−1 and 0.22 mol m−2 s−1, respectively). One-year-old leaves had significantly higher leaf CO2 assimilation rate than current-season leaves from April to June, for all cultivars. From August and then, leaf CO2 assimilation rate in current-season leaves was higher than in 1-year-old leaves. There were no significant differences in leaf CO2 assimilation rate between fruiting and vegetative shoots. Total chlorophyll (a + b) content increased with leaf age in current-season leaves. In 1-year-old leaves chlorophyll content increased in spring, then started to decrease and increased slightly again late in the season. Chlorophyll content was higher in 1-year-old leaves than in current-season leaves throughout the season. Total specific leaf weight (SLW) increased throughout the season for all cultivars. Stomatal density in lower leaf surface was lowest for ‘Koroneiki’ (399 mm−2) and highest for ‘Megaritiki’ (550 mm−2). Our results showed differences in leaf CO2 assimilation rate among the five different olive cultivars, with a diverse genetic background, ranging from 12 to 21 μmol m−2 s−1. From the five cultivars examined, ‘Koroneiki’, a drought resistant cultivar, performed better and was able to maintain higher leaf CO2 assimilation rate, even under high air vapor pressure deficit. All cultivars had a pronounced seasonal variation in leaf CO2 assimilation rate, affected by date of the year, depending on ambient conditions. The high temperatures and high air vapor pressure deficit occurring during summer caused a reduction in leaf CO2 assimilation rate in all cultivars. Leaf CO2 assimilation rate was also affected by leaf age for all cultivars, with old leaves having significantly higher leaf CO2 assimilation rate than young leaves early in the season.  相似文献   

11.
Summary

The effects of CO2 concentration (350 and 1200 μmol mol-1), growing media (peat + perlite, 3:1, peat + coco dust, 1:1; and coco dust alone), and concentration of nutrient solution (EC 2.1 and 2.8 mS cm-1) on growth of gerbera microcuttings, leaf nutrient content, and the chemical properties of the growing media were investigated. Plants grown in peat + coco dust had the highest dry weights of leaves and roots. There were no significant differences in the fresh and dry weights of leaves and roots due to concentration of nutrient solution. CO2 enrichment increased all growth variables, except leaf number. Leaf nutrient content of gerbera cuttings and chemical properties of growing media after eight weeks of growth, with reference to all treatments, are discussed and presented as tables.  相似文献   

12.
Blueberry can readily be shaded as a bush type plant, maybe affecting its growth and photosynthesis. Growth and photosynthetic characteristics of ‘Bluecrop’ blueberry grown under various shade levels were investigated to understand acclimation under shade conditions and to determine the optimal light conditions for agricultural purpose. Shade decreased the number of shoots per shrub, but increased shoot length. However, shade did not affect the number of leaves on the main axis. With increasing shade level, leaf length, width and area increased, but leaf thickness decreased. However, there was no obvious tendency in leaf length/width ratio with increasing shade level. Shade leaves had less dense stomata than sun leaves, but stoma was bigger in shade leaves than in sun leaves. With increasing shade level, non-photochemical quenching in blueberry leaves increased and the values were higher at low photosynthetic photon flux densities (PPFDs) in shade leaves than in sun leaves, resulting in the decreases in quantum yield, electron transport rate and net CO2 assimilation rate (An). The maximum An at 31, 60, 73 and 83% shade levels was 11.8, 11.0, 8.4 and 7.5 μmol m−2 s−1, respectively. Following the slight decrease up to 100 μmol m−2 s−1 PPFD, stomatal conductance (gs) linearly increased up to 600 μmol m−2 s−1 PPFD and became saturated at all shade levels. The leaves of the shrubs grown under the 83% shade level had a significantly lower gs as compared to the leaves of the shrubs grown under the 31, 60 and 73% shade levels. Transpiration rate (E) linearly increased up to 600 μmol m−2 s−1 PPFD and was saturated at the 73 and 83% shade levels. However, E increased linearly at both 31 and 60% shade levels with increasing PPFD. The reproductive growth characteristics such as number of flowers, fruit set rate per flower bud and fruit yield also significantly decreased with increasing shade level. For agricultural purpose, therefore, shade level above approximately 60% of full sunlight must be avoided for optimal photosynthesis and growth of the ‘Bluecrop’ blueberry.  相似文献   

13.
To study the effects of day and night temperature difference (DIF) on tomato growth, a controlled experiment using Solanum lycopersicum L., cv. Jinguan 5 was conducted. The daily mean temperature (Tm) was maintained at 18°C and 25°C, and the DIF was set at 0°C, 6°C, and 12°C. The results indicated that chlorophyll a (Chl a) and chlorophyll b (Chl b) gradually increased as DIF rose. At 18°C Tm, the carotenoid content reached a maximum at 12°C DIF. The Chl a/Chl b, net photosynthetic rate (PN), photosynthetic rate at irradiation saturation (Pmax), stomatal conductance (gs), intercellular CO2 concentration (Ci), stomatal limitation value, the maximum assimilation rate (Amax), apparent quantum efficiency (Aq), carboxylation efficiency (Ce), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), gibberellin A3 (GA3), and indole-3-acetic acid (IAA) were highest, while malondialdehyde (MDA) was lowest at 6°C DIF. At 25°C Tm, PN, Pmax, Amax, Aq, Ce, gs, Ci, CAT, POD, GA3, IAA, and zeatin reached the maximum under 6°C DIF, while SOD and MDA reached the maximum under 12°C DIF. Furthermore, the morphological index peaked at 6°C DIF under 18°C and 25°C Tm. The results suggested that 6°C DIF improved the growth and development of tomato during the flowering stage. ABBREVIATIONS: Aq – apparent quantum efficiency; Amax – the maximum assimilation rate; CAT – Catalase; Chl a(b) – chlorophyll a(b); Ca – ambient CO2 concentration; Ce – carboxylation efficiency; Ci – intercellular CO2 concentration; DIF – difference between day temperature (TD) and night temperature(TN); FM – fresh mass; gs – stomatal conductance; GA3 – gibberellin A3; IAA – indole-3-acetic acid; Ls – stomatal limitation value; MDA – malondialdehyde; Pmax – photosynthetic rate at irradiation saturation; PN – net photosynthetic rate; POD – peroxidase; ROS – reactive oxygen species; SOD – superoxidedismutase; Tm – daily mean temperature; ZT – zeatin.  相似文献   

14.
Two experiments were conducted under greenhouse conditions to evaluate the effects of sink removal (flower shoot harvest and debudding) on the gas-exchange capacity (i) of leaves left on the parent shoot after flower shoot harvest and (ii) of flower shoot leaves after flower-bud removal. In the first experiment, gas-exchange measurements were performed on three 5-foliate leaves (leaf 1: uppermost parent shoot leaf, and two leaves inserted just below: leaves 2–3). It was found that, after bud sprouting, the leaf nearest to the young growing shoot (leaf 1) experienced a significant reduction in leaf maximum net CO2 assimilation rate, Alm, stomatal conductance, gs, and transpiration rate, El, over time in comparison to the corresponding values observed for leaves 2–3. Leaf water use efficiency, WUE, significantly changed over time, while the ratio of leaf internal to ambient CO2 concentration, Ci/Ca, was rather conservative throughout the entire shoot growing period. In the second experiment, leaf gas-exchange measurements were performed for adult flower shoots that were either debudded or left intact. Both types of shoots exhibited a similar along-shoot distribution pattern of physiological fluxes, gs, and WUE. Bud removal did not significantly affect the magnitude of gas-exchange, with the exception of El. One week after bud removal, only slight differences were observed for Alm, gs and El between the two types of shoots. These results suggest (i) that the contribution of the uppermost parent shoot leaf to the assimilates demand of newly growing shoot significantly affects its photosynthetic capacity; and (ii) that flower-bud removal does not change the overall photosynthetic capacity of the flower shoot leaves, which divert the surplus of produced assimilates towards alternative sink organs and plant reserve pools.  相似文献   

15.
《Scientia Horticulturae》2005,105(2):197-211
CO2 concentration was monitored during three 15-day subculturing cycles in vessels containing actively proliferating plum cultures of Prunus cerasifera, clone Mr.S. 2/5. The effects of two photosynthetic photon flux density regimes: 50 ± 5 μmol m−2 s−1 and 210 ± 5 μmol m−2 s−1 were compared. Three distinct phases in the CO2 trend were distinguished during each culturing cycle of both light treatments. In the first, occurring at the beginning of the culture cycle, the amount of CO2 emitted by the cultures during dark periods was greater than that assimilated during the light periods. In the second phase, the opposite trend was detected, while in the third, the range of CO2 day–night fluctuations increased or remained stable according to the number of explants per vessel. The treatment with 210 ± 5 μmol m−2 s−1 did not modify the CO2 phase trend but induced more pronounced fluctuations in day–night CO2 concentration. Under this light treatment, cultures reached CO2 compensation point for a period as long as 48% of the total number of light hours, while under 50 ± 5 μmol m−2 s−1, it was only 8%. The different range in CO2 day–night fluctuations monitored throughout a subculturing cycle, appeared to be mainly induced by changes in culture growth dynamics.  相似文献   

16.
Bal  Erdinc  Torçuk  Ali İzzet  Özer  Cengiz 《Erwerbs-Obstbau》2022,64(2):127-133

The study was carried out to determine the effect of melatonin on quality and postharvest life of sweet cherries (Prunus avium L.) cv. ‘Sweetheart’ during storage. The fruits were dipped at different concentrations of melatonin (0, 250, 500 and 1000?µmol l?1 for 10?min) and distilled water as control. The changes of sweet cherries were assessed at 7?day intervals by evaluating the following quality parameters: firmness, soluble solids content, titratable acidity, respiration rate, color values (L* and chroma), ascorbic acid content, total anthocyanin content, total phenolic content, and antioxidant activity. The results showed that increasing the dose to 1000?µmol l?1 melatonin had a remarkable effect on maintaining the quality of sweet cherry. 1000?µmol l?1 and 500?µmol l?1 melatonin treatments significantly inhibited the decrease in firmness, ascorbic acid, total phenols, total anthocyanin, antioxidant content and reduced color changes and respiration rate. However, the total soluble solids content and titratable acidity of the fruit were not influenced by melatonin applications. These findings indicate that melatonin treatment may be effective in maintaining quality and bioactive compounds of sweet cherry fruit.

  相似文献   

17.
Net photosynthesis and dark respiration from whole plants of various tomato genotypes were measured in a closed system. At low irradiance (27 W m?2) and low external CO2 concentration (550 mg m?3), net photosynthesis of 10 genotypes was found to vary between 0.122 and 0.209 mg CO2 m?2 s?1. Correlation was observed between net photosynthesis, net uptake on a daily basis (8 h photoperiod at 20°C and 16 h nyctoperiod at 10°C), specific leaf weight and leaf area ratio. At high irradiance (243 W m?2), high external CO2 concentration (1480 mg m?3) and ambient temperatures of 10, 18, 20 and 26°C, four genotypes were analysed. ‘F6 I.V.T.’ had the highest rate of photosynthesis at 10°C, while ‘Sonatine’ ranked high at 26°C. Dark respiration increased with temperature, except in the case of ‘Bonabel’ where the effect of temperature was slight.  相似文献   

18.
《Scientia Horticulturae》2005,106(2):203-212
Cultivation of roses in various soil-less media was studied with the aim to identify the optimum soil condition for rose production. Madelon roses grafted on rootstock of Rosa indica var. major were transplanted to polyethylene bags containing zeolite and perlite (at ratios of 25z:75p, 50z:50p, 75z:25p and 100z:0p, v/v) in a climate-controlled greenhouse. Net photosynthesis (Anet), stomatal conductance (gs) and water use efficiency (WUE) of roses were followed for 5 months. Flower production and quality were recorded in three flowering flushes during a 5-month period. Analysis of variance of repeated measurements showed that even though the overall Anet did not differ among treatments (average 18.7 μmol m−2 s−1), trends in Anet seasonality for roses in 25z:75p substrate differed significantly from those in 50z:50p, 75z:25p or 100z:0p. Stomatal conductance did not show any significant seasonality or trends in response to substrate mixtures, averaging 0.89 mol m−2 s−1. Water use efficiency was significantly lower for roses in 25z:75p than in 100z:0p mixtures (1.8 ± 0.15 and 2.0 ± 0.13 μmol m−2 s−1 CO2/mmol m−2 s−1 H2O, respectively). Cumulative production of rose plants did not differ among substrate mixtures. Productivity significantly differed among flower stem classes. Stem class I (>70 cm) and class V (≤30 cm) exhibited the least production, contributing to only 7.6 and 3.7% of the total production, respectively. The highest productivity was observed in classes III (51–60 cm) and IV (31–50 cm), contributing to the bulk of productivity (68.4%). Class II contributed a 20.3% of the production. Results showed that zeolite and perlite acted as inert materials. Zeolite did not exert any positive effect on productivity, in contrast to what has been reported in literature recently. Use of perlite resulted in a little improvement in photosynthesis, however this improvement was not reflected by a significant increase in production.  相似文献   

19.
高浓度CO2 对蝴蝶兰CO2 吸收速率和生长的影响   总被引:1,自引:0,他引:1  
 研究了CO2 (700 ±50) μmol·mol-1、(1 000 ±50) μmol·mol-1、(360 ±30) μmol·mol-1(对照) 对蝴蝶兰CO2吸收速率和生长的影响。研究结果表明: 蝴蝶兰叶片净CO2吸收速率在02∶00 达到最大, 可滴定酸积累在04∶00 达到最高; CO2加富显著提高蝴蝶兰夜间的CO2吸收速率, 在处理30 d时, 所测得的CO2吸收速率的增幅分别为同期对照的134.11%和435.3% , 可滴定酸积累的分别比对照增加65.05%和119.42% , 随着处理时间的延长, CO2吸收速率增幅逐渐下降; CO2加富促进了叶片碳水化合物(可溶性糖和淀粉) 的积累, 在CO2 (1 000 ±50) μmol·mol-1处理组中碳水化合物积累的促进尤为明显;总生物量的测定表明, 处理60 d, 鲜样质量比同期对照增加了23%和49% , 干样质量增加了38%和57% ,处理150 d时, 鲜样质量比对照增加了50%和94% , 干样质量增加了19%和64%。以上结果表明CO2加富能显著促进蝴蝶兰的生长。  相似文献   

20.
Much of the remaining native rangelands in Canada are topographically complex. The flux of greenhouse gases (GHGs) in rangelands of hummocky terrain has not been adequately studied, leaving a gap in the national GHG sources and sinks budget. The objectives of this study were to determine the effects of topography and mowing on carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) flux and to correlate these fluxes to abiotic and biotic factors. GHG flux was studied on six landform elements, including north-facing concave and, south-facing concave and convex, upland and depressions, in the Northern Mixedgrass Prairie of Canada over 2 years with mowing being imposed in early spring. GHG fluxes showed strong temporal variations, ranging from 3.0 to 40.4 kg CO2–C ha?1 d?1, 0.1 to 2.6 g N2O–N ha?1 d?1, and ?0.25 to ?0.01 g CH4–C ha?1 d?1. GHG fluxes responded to changes in soil water and soil temperature across the landscape. The largest production of CO2 was recorded in depression mainly due to its more favourable soil water conditions. Mowing enhanced CO2 flux more than CH4 and N2O fluxes. Dominant plant species varied among the six landform elements, but using plant community type as the direct indicator for GHG emissions in grasslands may not always be reliable when precipitation is low. The net emissions of GHGs from Saskatchewan rangeland was relatively low, but the potential to increase emissions through changes in land management could be high. Our results suggest that in the Mixedgrass Prairie, best management practices for maintaining grassland health such as moderate grazing may also reduce GHG emissions.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号