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1.
《Scientia Horticulturae》2001,88(1):11-29
We investigated the hypothesis that manipulating water out-flow of a plant through the shoot environment (potential transpiration, ET0) in a glasshouse could modulate the effect of salinity/osmotic potential in the root environment upon yield of tomatoes. Contrasting root-zone salinity treatments were combined with two climate treatments — a reference (high transpiration, HET0) and a “depressed” transpiration (low transpiration, LET0). The salinity treatments, characterised by their electrical conductivity (EC) were 6.5, 8 and 9.5 dS m−1, were always coupled with a reference treatment of EC=2 dS m−1. In another experiment, concentrated nutrients (Nutrients) and nutrients with sodium chloride (NaCl) at the same EC of 9 dS m−1 were compared.Marketable fresh-yield production efficiency decreased by 5.1% for each dS m−1 in excess of 2 dS m−1. The number of harvested fruits was not affected; yield loss resulted from reduced fruit weight (3.8% per dS m−1) and an increased fraction of unmarketable harvest. At the LET0 treatments, yield loss was only 3.4% per dS m−1 in accordance with the reduction in fruit weight. Low transpiration did increase fruit fresh yield by 8% in both NaCl and Nutrients treatments at an EC=9 dS m−1. Neither EC nor ET0 affected individual fruit dry weight. Accordingly, fruit dry matter content was significantly higher at high EC than in the reference (4% per each EC unit in excess of 2 dS m−1) and responded to ET0 to a minor extent. Control of the shoot environment in a greenhouse to manipulate the fresh weight of the product may mitigate the effects of poor quality irrigation water without affecting product quality. 相似文献
2.
《Scientia Horticulturae》2005,106(2):147-161
Pepper plants grown in recirculating nutrient solution were exposed to NaCl-salinity (60 mM NaCl, 8 dS m−1) imposed either to the entire or to half of the root system and compared to plants supplied with a standard nutrient solution (1.9 dS m−1). The saline solution was obtained by adding NaCl to the standard nutrient solution. In the split-root treatment, the root compartment not exposed to salinity was supplied with raw water (0.38 dS m−1). Both the stem and the root dry weights were markedly restricted by salinity, irrespective of salinizing half or the entire root system. In the split-root treatment, the dry weight of the root compartment receiving raw water did not differ significantly from that exposed to salinity. The net photosynthesis and the leaf chlorophyll content were restricted by both salinity treatments, but the decrease was more marked when the entire root system was exposed to salinity. In contrast, the stomatal conductance and the transpiration rate were equally reduced, regardless of salinizing the entire or part of the root system. The leaf Na and Cl concentrations were raised by the NaCl-salinity, but only in one sampling date the increase was significantly higher when the entire root zone was exposed to salinity, as compared with salinization of half of the root system. Salinity reduced significantly the leaf K, Ca, and Mg uptake but not to levels that could cause nutrient deficiencies. These results indicate that pepper is susceptible to high salinity, predominantly due to reduced stomatal conductance. However, after long-term exposure to salinity the growth may be suppressed due also to inhibition of photosynthesis at chloroplast level. The adverse effects of high NaCl-salinity are hardly mitigated when only a part of the root system is salinized, which indicates that the response is governed by root exposure to high NaCl concentrations and not by inefficiency of the roots to take up water. 相似文献
3.
Increasing use of recycled water that is often high in salinity warrants further examination of irrigation practices for turfgrass health and salinity management. A study was conducted during 2011–2012 in Riverside, CA to evaluate the response of perennial ryegrass (Lolium perenne L.) ‘SR 4550’ turf to varying quality and quantity of irrigation water. A modified line-source sprinkler irrigation system provided a salinity gradient (ECw ∼0.6–4.2 dS m−1) in between lines. Irrigation was scheduled in four separate irrigation zones perpendicular to the irrigation lines according to 80, 100, 120, and 140% ETo. Changes in turf quality (R2 = 0.30***), were primarily driven by the number of days that the area had been irrigated with saline water. When data were separated by irrigation amount, both time and water quality accounted for 54% and 46% of the variability (P < 0.001) in quality and cover, respectively at 80% ETo. A model was created to quantify decline in turf quality in relationship to %ETo replacement and salinity accumulation in the rootzone (R2 = 0.57). Our results suggest that perennial ryegrass requires irrigation scheduling at 140% ETo, irrigation water quality below ECw ∼1.7 dS m−1, and ECe below 3.8 dS m−1 to maintain acceptable quality for 442 d in Riverside, CA. 相似文献
4.
《Scientia Horticulturae》2001,89(1):9-21
This paper analyses the response of vegetative growth of greenhouse tomato to both root-zone salinity and shoot-environment (potential transpiration), with the purpose of explaining the observed lack of effect on dry matter yield. A reference salinity (EC) of 2 dS m−1 was compared in three experiments with, respectively, 6.5, 8 and 9.5 dS m−1. Another experiment investigated specific effects of sodium chloride, by comparing two high-EC treatments (both 9 dS m−1), one with a high concentration of nutrients and one with addition of sodium chloride to a normal nutrient solution. The shoot-environment was either a “normal” climate regime or the same regime but with depressed potential transpiration, mainly by adaptation of the humidity set point. There was no detectable effect of the potential transpiration treatment, neither of the sodium chloride. Salinity effects on vegetative growth only showed up at EC exceeding 6.5 dS m−1. The most evident EC effect was a reduction of leaf expansion; individual leaf area was reduced by 8% per dS m−1 exceeding 6.5. This was partly compensated by a slight increase (2% per unit EC) in the number of leaves, which explains why cumulative plant leaf area decreased by about 7% per unit EC in excess of 6.5 dS m−1. Therefore, leaf area index (LAI) at the highest EC was reduced by some 20% compared to the LAI at an EC of 2 dS m−1. It is estimated that this would cause a reduction of less than 8% in light interception, and thus in dry matter produced. Indeed, differences observed in dry weight between the EC treatments were never significant. 相似文献
5.
《Scientia Horticulturae》2002,92(1):41-54
The long-term effect of saline water irrigation on flower yield and quality was investigated in three herbaceous cut flower crops of commercial importance, the Emily cultivars of Japanese limonium, Trachelium caeruleum and Eustoma grandiflorum (lisianthus), and in two bulb species, Hippeastrum hybridum and Ornithogalum arabicum. Among the tested crops, limonium showed the highest resistance to salinity. Irrigation water with an electrical conductivity of up to 11.5 dS m−1 had little or no effect on stem yield and length of limonium flowering stems. In Trachelium, salinity had no effect on the yield of flowering stems or the size of the inflorescence, but it markedly reduced stem weight and length. The concomitant reduction in the number of nodes to flowering was reflected in earlier flower initiation. Since delayed flower differentiation and over-elongation of Trachelium stems is a serious problem during the winter months, application of mildly saline irrigation for winter production could be used to induce earlier flower initiation and to control stem height. In lisianthus subjected to salinity from bud appearance onwards, a salinity level of 6.0 dS m−1 increased stem weight and the number of flowers per stem without affecting other quality parameters. The work carried out with Trachelium and lisianthus, although limited, indicates that salinity may be used for improving the quality of some cut flowers. In contrast to its beneficial effect on the herbaceous species, salinity led to a significant reduction of bulb, leaf, and root weight of the two bulbous species, H. hybridum and O. arabicum. 相似文献
6.
Shigeoki Moritani Tahei Yamamoto Henintsoa Andry Mitsuhiro Inoue Koh Kato Hirotaka Saito 《Urban Forestry & Urban Greening》2013,12(3):338-343
In dryland areas, secondarily treated municipal wastewater could be used in extensive green roof systems. In this study, the effects of water and salt stress on a crassulacean acid metabolism (CAM) plant, Sedum kamtschaticum Fischer, was evaluated under intermittent saline irrigation. The salinity of irrigation water varied from 6.0 to 18.0 dS m?1. A reduction in soil water content and an increase in soil water electrical conductivity (EC) were observed during the irrigation interval (5–17 d) as a result of evapotranspiration (ET). The effect of soil water potential (SWP) on reduction of the ET ratio (ETr) was successfully described with an equation that could be applicable to a wide range of soil salinities and water contents, to estimate ET. In this study, the stress factor was defined as the integration of solute potential, and matric potential less soil water content for optimum growth (less than ?0.1 MPa) with elapsed time. The stress factor rapidly reduced total ET in CAM plants but effectively increased water-use efficiency (WUE). Thus, by using CAM plants for green roofs under intermittent saline irrigation, the need for irrigation water is reduced without a considerable loss of plant biomass. 相似文献
7.
《Scientia Horticulturae》2005,105(2):163-175
The main objective of this study was to analyse the transpiration time course of soilless culture cucumber plants (Cucumis sativus L.) during two cycles, at low (up to 9 MJ m−2 d−1) and high (up to 20 MJ m−2 d−1) radiation levels, and their relationship with greenhouse climate parameters (incident radiation and vapour pressure deficit, VPD) and canopy development. The coefficients of the simplified Penman–Monteith formula were calibrated in order to calculate the transpiration rate of the crop, to help improve irrigation management in substrate cultivation. The transpiration rate per ground surface area was measured by weighing plants with an electronic balance.At high radiation levels, the diurnal canopy transpiration rate was four times higher than at low radiation levels and the night transpiration rate reached values between 120 and 200 g m−2 d−1 in both cases. The leaf transpiration rate decreased during crop ontogeny and was higher in the afternoon than in the morning for the same value of radiation, whereas a linear relationship with the VPD was found even for values greater than 3 kPa. The results showed that the fitted simplified Penman–Monteith formula accounted for more than 90% of the measured hourly canopy transpiration rate, signifying that this formula could be used to predict water requirements of crops under Mediterranean conditions and improve irrigation control in a substrate culture. However, the model coefficients will have to be adjusted for specific climate and crop conditions. 相似文献
8.
《Scientia Horticulturae》2005,103(3):289-303
In a 2-year field study, strawberry cvs. ‘Elsanta’ and ‘Korona’ were exposed to three different levels of NaCl salinity supplied as aqueous solutions characterised by electrical conductivities of 0.3 dS/m, 2.6 dS/m, and 5.1 dS/m. Salinity in the rhizosphere reduced plant growth by up to 44% in ‘Korona’ and 90% in ‘Elsanta’. A rather distinct cultivar difference represented the reduction in leaf area per plant of 85% in the second year of experiment in ‘Elsanta’ compared to 29% in ‘Korona’. Strawberry can be regarded as a Na+ excluder, because Na+ content of both strawberry cultivars remained below 3 mg g−1 dry mass at all salinity levels. Cl− content increased considerably, up to 70 mg g−1 dry mass in ‘Korona’ and 80 mg g−1 dry mass in ‘Elsanta’ plants. ‘Korona’ retained most of its Cl− in roots and crowns, whereas in ‘Elsanta’ the maximum was detected in petioles. ‘Korona’ was able to accumulate up to 33% higher Cl− content in the roots than ‘Elsanta’. Macronutrient deficiency due to NaCl salinity was not observed and in comparison to ‘Elsanta’, higher Cl− content in roots of ‘Korona’ did not coincide with an impairment of macronutrient uptake. Salinity stress reduced fruit yield by up to 27% in ‘Korona’ and 64% in ‘Elsanta’. Fruit quality, characterised as taste, aroma, and texture by a consumer-type panel, decreased by more than 24% in ‘Elsanta’, but in ‘Korona’ differences were insignificant. Total soluble solids (Brix) and the ratio Brix/TA (TA, titratable acid) decreased significantly by about 20% in ‘Korona’ and 35% in ‘Elsanta’. To summarise, the ability of ‘Korona’ to retain Cl− in the root system more effectively than ‘Elsanta’ resulted not only in a 41% lower leaf Cl− content at the highest salinity level and a better growth under NaCl stress, but also in a relatively higher fruit yield and fruit quality. 相似文献
9.
《Scientia Horticulturae》2003,97(3-4):353-368
Four-month-old potted Cistus albidus and Cistus monspeliensis plants growing in a greenhouse were submitted to saline stress from 9 August to 2 December, using irrigation water containing 0, 70, and 140 mM NaCl. C. monspeliensis plants are more tolerant to saline irrigation water than C. albidus plants, mainly due to their capacity to resist stress with a lower plant biomass and canopy area; furthermore, they showed no leaf necrosis symptoms. Under saline stress conditions the main growth limiting factor in both species was photosynthesis. Both Cistus species responded to saline stress by developing avoidance and tolerance mechanisms. The avoidance mechanisms took place at a morphological and physiological level. Morphologically, the reduction in the canopy area can be considered a mechanisms for regulating water loss via transpiration. Treated C. monspeliensis plants showed a greater capacity to absorb water and were able to conserve it more efficiently than C. albidus plants. Tolerance mechanisms included Na+ and Cl− inclusion and osmotic adjustment. However, the reaction of each species to osmotic adjustment was different, because in C. monspeliensis plants the osmotic adjustment was unable to prevent a decrease in leaf turgor. The curvilinear relationship between Pn and gl observed in C. monspeliensis plants indicated stomatal limitation of photosynthesis below a leaf conductance of about 160 mmol m−2 s−1. In C. albidus plants, a linear relationship between photosynthesis and leaf conductance rather a curvilinear model was significant, indicating limitation of the photosynthetic capacity. 相似文献
10.
The application of de-icing salts for winter road maintenance is recognized as a major contributor to the decline of urban trees. We conducted a long-term monitoring program across several locations in the City of Edmonton (Alberta, Canada) to evaluate the impact of roadway salt application on tree species widely planted in boulevards and right-of-ways: Ulmus americana, Fraxinus pennsylvanica, Pinus contorta, and Picea glauca. Soil and leaf samples were collected from a total of 16 sites over six years. There were four sites selected for each tree species: three mid- to high- traffic roadside sites that received regular winter maintenance and one non-serviced site (control). Sampling was performed three times per year from late spring to late summer. Airborne salinity was assessed in four locations at different distances from the road. In 50% of the roadside sites, soil electrical conductivity (EC) values exceeded 2 dS m−1. Soil pH in all of the roadside sites was also significantly higher than in the control sites, with values ranging from 7.6 to 8.5. In all four species, trees growing in sites with high soil EC had increased leaf Na concentrations and reduced leaf chlorophyll concentrations. Among the airborne monitoring sites, Na deposition in high traffic locations was over four-fold higher than those measured in the control location. Furthermore, Na levels remained relatively high at 20–50 m from the main road. Our data suggest that while soil salinity is among the main stressors affecting roadside trees in Edmonton, salt spray deposition may also have a significant impact on trees located close to high vehicle traffic areas and dense road networks. Our study highlights the importance of collecting data over several years and from multiple locations to account for the spatial and temporal heterogeneity of the urban environments in order to better evaluate the impact of road salt application on urban trees. 相似文献
11.
《Scientia Horticulturae》2001,89(2):91-101
The effects of NaCl stress on in vitro tuberization of potato species were studied. Three species of potato (Solanum tuberosum L., S. curtilobum Juz. and Bukasov, and S. juzepczuckii Bukasov) differing in frost resistance were subjected to 0, 25, 50, 75, and 100 mmol l−1 NaCl. Stolon growth and microtuberization were evaluated. The in vitro induced microtubers were characterized with respect to their carbohydrate composition by measuring reducing, non-reducing, total soluble sugars and starch contents. Tuberization and stolon growth, expressed by stolon height or fresh mass, were significantly affected by salinity. The highest saline level (100 mmol l−1 NaCl) completely inhibited tuber development in all species, but not stolon growth. Stolon growth for sensitive species (S. tuberosum) had a significant decrease, whereas both frost tolerant species (S. juzepczuckii and S. curtilobum) tended to increase stolon length with increasing saline levels. Salinity differentially influenced sugar accumulation among potato genotypes. The starch levels in both, S. curtilobum and S. juzepczuckii, remained constant under all salt levels, whereas starch increased in S. tuberosum microtubers. 相似文献
12.
《Scientia Horticulturae》2005,104(3):275-292
Forty-one herbaceous species were grown under short-days (8 h photoperiod, ambient irradiance averaged 12–13.2 and 6.4–8.3 mol m−2 day−1 for Experiments I and II, respectively) with or without supplemental high-pressure sodium lighting (+50, 100, or 150 μmol m−2 s−1); or under long-days delivered using natural day lengths and irradiance with night interruption lighting (2200–0200 h at 2 μmol m−2 s−1 from incandescent lamps) or under ambient daylight plus supplemental irradiance during the day and as a day extension to 18 h (0800–0200 h) with supplemental high pressure sodium lighting (+50, 100, or 150 μmol m−2 s−1) to identify the impact of photoperiod and irradiance on flowering of each species. Days to first open flower, leaf number below first flower, and mean dry weight gain per day (MDWG) were measured when the first flower opened. Twenty-seven species were photoperiodic with examples of five photoperiodic response groups represented: obligate short-day (2), facultative short-day (5), obligate long-day (16), facultative long-day (4); 13 were day neutral (no photoperiod response in flowering). One species, Salvia sclarea L., did not flower. A facultative irradiance response was observed with 10 species; 28 species were irradiance indifferent; 2 had delayed flowering as irradiance increased. Photoperiod affected MDWG of 30 species. Increasing irradiance affected MDWG with 14 species. Photoperiod interacted with irradiance to affect MDWG of 11 species. Cobaea scandens had the greatest MDWG (0.40 g day−1) while Amaranthus hybridus had the least MDWG (0.01 g day−1) across photoperiod and irradiance levels. 相似文献
13.
《Scientia Horticulturae》2005,104(3):325-337
The influence of 24 h mean air temperature (18.3, 20.6, 23.9 and 25.8 °C) and photosynthetic photon flux (PPF; 0.6, 2.1, 3.7 and 4.7 mol m−2 d−1) on the growth cycles of vegetative growth in Ilex × meserveae (‘Blue Princess’ S.Y. Hu) was investigated. Plants propagated from top cuttings were grown in greenhouse compartments. The number of unfolded leaves was recorded continuously throughout the experiment. A modified sine function was fitted to collected data and the values for the amplitude and frequency of the growth curves were analysed. The sine function was tested as a method to evaluate the influence of climate on periodically flushing species. Both amplitude and frequency were significantly influenced by air temperature and PPF. The highest frequency of flushing was found at 23.9 °C and 3.7 mol m−2 d−1. The function resulted generally in a good fit to collected data with R2 values above 0.9. Growth curves of all individual plants were categorised with respect to their growth pattern as poor synchronisation within the treatments did not allow analysis of the mean values of the growth curves. 相似文献
14.
《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
15.
16.
《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
17.
《Scientia Horticulturae》2001,87(1-2):93-105
Campanula carpatica Jacq. ‘Blue Clips’ plants were grown in a greenhouse under nine combinations of day and night temperatures created by moving plants every 12 h among three day/night temperatures (15, 20, and 25°C). At each temperature, there were three daily light integrals (DLI; 4.2, 10.8, and 15.8 mol m−2 per day, averaged over the experimental period) created with varying supplemental light, and ambient (≈400 μmol mol−1) and enriched (≈600 μmol mol−1) CO2 concentrations. Time to flower was closely related to average daily temperature (ADT), and was not significantly affected by the day or night temperatures delivered to achieve a specific ADT. Time to flower was not largely affected by DLI or CO2 enrichment. As plant ADT increased between 15 and 25°C, flower diameter decreased about 1 mm per degree and was not related to the difference between day and night temperatures (DIF). Flower diameter was smallest and least sensitive to changes in temperature at lower DLI and at ambient CO2 levels. There were 10 less flower buds and 0.3 g less dry mass per plant at first flower for every 1° increase in plant ADT at high and medium DLIs. Flower bud number and dry mass were relatively low and less sensitive to changes in ADT at low DLI, and increased slightly with CO2 enrichment at medium and high but not at low DLI. Plant height was not related to ADT, but increased linearly as DIF increased from −6 to 12°C at all DLIs, but the response was stronger under low DLI than high and medium DLIs. Flower bud number and dry mass were correlated closely with the ratio of DLI to daily thermal time (base temperature of 0°C). Flower bud number and dry mass were highest when C. carpatica plants were grown at 15°C with a DLI of 10–15 mol m−2 per day. 相似文献
18.
Promoting the plant diversity of urban green spaces is crucial to increase ecosystem services in urban areas. While introducing ornamental plants can enhance the biodiversity of green spaces it risks environmental impacts such as increasing emissions of biogenic volatile organic compounds (BVOCs) that are harmful to air quality and human health. The present study, taking Qingdao City as a case study, evaluated the plant diversity and BVOC emissions of urban green spaces and tried to find out a solution to increase biodiversity while reducing BVOC emissions. Results showed that: (1) the species diversity and phylogenetic diversity of trees in urban green spaces were 22% and 16% lower than rural forest of this region; (2) urban areas had higher BVOC emission intensity (2.6 g C m−2 yr−1) than their rural surroundings (2.1 g C m−2 yr−1); (3) introducing the selected 11 tree species will increase 15% and 11% of species diversity and phylogenetic diversity, respectively; and (4) the BVOC emissions from green spaces will more than triple by 2050, but a moderate introduction of the selected low-emitting trees species could reduce 34% of these emissions. The scheme of introducing low-emitting ornamental species leads to a win–win situation and also has implications for the sustainable green space management of other cities. 相似文献
19.
《Scientia Horticulturae》2001,87(4):275-290
The optimal growth regulator addenda for adventitious shoot regeneration in epicotyl cuttings of Troyer citrange (Citrus sinensis×Poncirus trifoliata) varied with the conditions of illumination. The response to illumination and to growth regulators differed for the direct and the indirect (through callusing) pathways of regeneration. Shoot formation through the direct organogenic pathway decreased as the concentration of benzyladenine (BA) in the medium was increased in the range 2.2–22 μM, when the explants were incubated in the dark or under an 8 h daylength. For explants incubated under a 16 h daylength, the number of shoots formed increased with BA concentration. Optimal conditions of incubation for shoot formation through the direct pathway were either an 8 h daylength with a photon flux density of 74 μmol m−2 s−1 in the presence of 2.2 μM BA, or a 16 h daylength with a photon flux density of 37 μmol m−2 s−1 in the presence of 22 μM BA. Irrespective of the conditions of incubation, shoot formation through the indirect organogenic pathway was suppressed by the addition of 22 μM BA to the medium. Optimal conditions for shoot formation through this pathway were incubation under an 8 h daylength at a photon flux density of 74 μmol m−2 s−1 in the presence of 2.2 μM BA. At the optimal conditions indicated, the addition of the synthetic auxin naphtaleneacetic acid (0.54 μM) reduced shoot formation. Irrespective of the pathway of regeneration, the number of shoots formed decreased markedly with the distance of the cutting from the cotyledonary node. 相似文献
20.
Mechanisms of salt stress tolerance in two rose rootstocks: Rosa chinensis ‘Major’ and R. rubiginosa
《Scientia Horticulturae》2001,87(3):207-216
The responses of two rose rootstocks Rosa chinensis ‘Major’ and R. rubiginosa were investigated under salt stress. The distribution of chloride and sodium ions in all plant parts was determined. The salt treatments were applied through irrigation water containing 0, 5, 10, 20 and 30 mM NaCl. Necrosis on the leaves as a result of the NaCl treatments was observed with in rootstocks after two months. Leaf injury was more pronounced in R. chinensis ‘Major’ than R. rubiginosa. The rootstock R. rubiginosa showed a higher tolerance to the NaCl stress than R. chinensis ‘Major’. The survival of the plants under increased NaCl stress as well as the extent of leaf injury could be used in the determination of tolerance of the rose genotypes. The lower older leaves contained higher concentrations of Cl− than the young upper leaves. Leaf samples had higher concentrations of Cl− than stem samples taken from the same positions. The roots contained higher amounts of Cl− than the stem samples. The plants accumulated higher amounts of Cl− in comparison with Na+. The lower leaves of R. chinensis ‘Major’ had higher amounts of Na+ than in all other parts whereas R. rubiginosa had higher concentrations of Na+ in the roots than in all other parts. 相似文献