Competition for water between inflorescences and leaves in cut flowering stems of Grevillea ‘Crimson Yul-lo’

Summary

Grevillea cv. ‘Crimson Yul-lo’ has large bright red terminal inflorescences on leafy stems and has recognised commercial potential as a cut flower crop. A major limitation is its relatively short vase-life, often terminated by early wilting of the inflorescence despite apparently turgid leaves. An investigation of the water relations of cut Grevillea ‘Crimson Yul-lo’ stems revealed that the water potential of inflorescences on intact stems in vases was significantly higher (i.e., less negative) than that of leaves from day-0 to day-3 of vase-life. Thereafter, the water potential of inflorescences declined more rapidly than that of leaves, accompanied by visible wilting of the tepals and styles of individual florets. Removal of leaves from the stems reduced both water uptake and water loss, and delayed the onset of a negative water balance in the inflorescence. Bagging of entire stems, leaves only, or inflorescences only, with micro-perforated plastic film to reduce transpiration, reducing leaf number to reduce leaf area, or supplying abscisic acid to reduce leaf stomatal aperture, all aided relative fresh weight retention by stems and extended vase-life. Four or six leaves on a stem caused greater loss in inflorescence water content than zero or two leaves. Considered collectively, these findings show that competition for water between the inflorescence and the leaves in cut Grevillea ‘Crimson Yul-lo’ stems contributes to the onset of inflorescence wilting and their short vase-life.     

Effect of green tea extract powder on the vase-life of fresh-cut rose (Rosa hybrida L.) ‘Carola’ stems

To develop an innocuous, easy-to-use, and inexpensive preservative for the cut flower industry, green tea extract (GTE) powder was applied in the fresh-cut rose stem preservation process to exploit its high anti-oxidative and anti-microbial properties. The effects of 2.0 g l^?1 GTE powder in the vase solution on the vase-life and flowering profile of cut rose (Rosa hybrida ‘Carola’) stems were investigated. The effectiveness of GTE powder was also compared with other preservatives such as 2% (w/v) sucrose, 200 mg l^?1 8-hydroxyquinoline citrate plus 2% (w/v) sucrose, or 0.2 mM silver thiosulphate in the vase solution, with distilled water as a control. The results showed that, compared to the control, the 2.0 g l^?1 GTE powder treatment extended the vase-life and reduced the loss in fresh weight in cut rose stems in the vase solution. GTE at 2.0 g l^?1 provided the highest anti-bacterial activity (4.2 log₁₀ CFU ml^?1 on day-6) and prevented the decline in anthocyanin concentrations compared to that seen in the control stems, suggesting that GTE powder could be used as a preservative to extend the vase-life of fresh-cut rose flowers.     

Cultivation of cut flower and bulb species with saline water

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.     

切花月季‘萨蔓莎’和‘加布里拉’失水胁迫耐性的差异

  不同失水胁迫条件下的研究结果表明: 切花月季耐失水胁迫品种‘萨蔓莎’和不耐失水胁迫品种‘加布里拉’的瓶插寿命缩短百分比、鲜样质量损失率、相对电导率、花朵乙烯生成量都随胁迫程度的增加而增加, 叶片、花朵水势随胁迫程度的增加而下降, 萨蔓莎的变化幅度比加布里拉小。中度失水胁迫的叶片和花瓣SOD、POD 活性高于轻度和重度胁迫。两个品种的叶片气孔阻力没有明显区别。瓶插期间,相同失水胁迫时间, 萨蔓莎复水恢复能力比加布里拉强。讨论了月季切花上述参数与失水胁迫耐性之间的关系。     

Effects of sink removal on leaf photosynthetic attributes of rose flower shoots (Rosa hybrida L., cv. Dallas)

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, A_lm, stomatal conductance, g_s, and transpiration rate, E_l, 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, C_i/C_a, 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, g_s, and WUE. Bud removal did not significantly affect the magnitude of gas-exchange, with the exception of E_l. One week after bud removal, only slight differences were observed for A_lm, g_s and E_l 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.     

保鲜液对蒟蒻薯切花瓶插寿命的影响

 蒟蒻薯（Tacca chantrieri Andre）是观赏价值较高的稀有黑色切花,但瓶插寿命较短,对其进行保鲜研究具有重要意义。用蔗糖、8–羟基奎宁（8-HQ）和柠檬酸按三因素二水平的正交设计配制瓶插保鲜液,通过观察切花形态变化,测定瓶插寿命和鲜样质量,研究瓶插液的保鲜效果。结果表明,与对照相比,各处理均能不同程度地延缓切花衰老,其中A处理,即2%蔗糖 + 100 mg · L^-1 8-HQ + 200 mg · L^-1柠檬酸 + 50 mg · L^-1 6-BA + 100 mg · L^-1 K₂HPO₄处理效果最好,花枝寿命和花须寿命分别比对照长17 d和14 d,是蒟蒻薯切花较好的瓶插保鲜配方。     

Citric acid,sucrose and Cu2+ as potential vase treatments for cut Acacia holosericea G. Don foliage stems

The short vase life of Acacia holosericea cut stems needs to be improved before they are marketable as cut foliage for floral arrangement. The effects of citric acid, Cu²⁺ and sucrose were investigated for their efficacy in postharvest treatments to extend vase life of the cut stems. Five experiments were conducted involved combinations of citric acid either with Cu²⁺ or sucrose. Vase life, relative fresh weight (RFW), and vase solution uptake were measured as indicators of cut stem quality. The effect of Cu²⁺ alone was shown to be consistently superior in improving vase life by up to 1.9-fold as compared with deionised water control. Citric acid had a smaller effect than Cu²⁺ and did not act synergistically with Cu²⁺. Sucrose on its own or in combination with citric acid did not improve vase life significantly; instead sucrose promoted early wilting or desiccation of the cut foliage.     

Improvement of flower color by means of leaf treatments in lily

Flower color, an important feature biologically and commercially, is based on four natural pigments – flavonoids, carotenoids, betalains and chlorophylls. Temperature, light, nutrition – as well as additions of sugar, salt, or metals to the conservation water – have an effect on pigmentation. We investigated the effects of K-sulphate and/or sucrose on flower color in leaf treatments applied 30–10 days before harvest to four Asiatic lily (Lilium × elegans Thunb.) cultivars during the winter and summer. Colors of tepals were evaluated by a portable spectrocolorimeter that calculates the standard CIE L*a*b* coordinates and the color differences (E). After leaf treatments during both seasons, cultivars with flowers with high red components (e.g. the purple ‘Fangio’ and the pink ‘Brindisi’) showed significant improvements in color quality. The orange-flowered ‘Tresor’ showed improvement only if K-sulphate and Mix (K-sulphate and sucrose) solution treatments were applied during the summer. The yellow-flowered ‘Menorca’ was not affected by treatments during either summer or winter forcing season. Especially in the winter, a significant reduction in flower abortion was observed for cut flowers of all cultivars. In summer only ‘Fangio’ and ‘Tresor’ showed a reduction in flower abortion. Also, flower size and longevity were improved by the leaf treatment. The results, obtained from a commercial nursery operation, demonstrate that lily growers can adopt a very simple and inexpensive treatment to improve important qualitative traits of their product.     

Analysis of light and sucrose potencies on petal coloration and pigmentation of lisianthus cultivars (in vitro)

To understand how the synthesis of petal pigments is influenced by light and sucrose, a cut flower culture was carried out with and without sucrose in the medium using different cultivars of lisianthus (Eustoma grandiflorum Grise.). At low light intensity, lightness (L¹) increased and chroma (C¹) decreased. In the presence of sucrose, lightness (L¹) decreased and chroma (C¹) increased. Light intensity and sucrose exerted significant influences on the percentage distribution of different anthocyanidins and total anthocyanin in lisianthus flower petals. Flowers from detached buds cultured in sucrose containing media showed a significant increase in anthocyanin concentration in all the cultivars; ‘Asuka no Asa’, ‘Mickey Rose’ and ‘Asuka no Kurenai’ at a light intensity of 1400 to 2100 lx. Furthermore, more anthocyanin was produced in the sucrose media. The amount of anthocyanin in the petals increased gradually with the lengthening of the photoperiod, whereas flavonol content showed no significant variation in response to light intensity or photoperiod. We found that the lightness, chroma and petal color of the flowers were influenced by sucrose and light intensity through a change in total anthocyanin concentration in petals. The variation in flower color caused by light and sucrose, determined on the basis of CIELAB color diagram, provides for a more accurate color notation in lisianthus.     

Changes in carbohydrate composition in lettuce flower stalks during development

Summary

Changes in carbohydrate composition in lettuce flower stalks were investigated during growth in order to check whether or not accumulated carbohydrates are used for the rapid development of flower stalks and seed formation. Sucrose was the predominant sugar in lettuce flower stalks, followed by fructans of low molecular weight, glucose and fructose.With regard to fructans, only 1-kestose and 1-nystose were detected, and they increased in concentration from the appearance of terminal flower buds to anthesis. Starch concentration was very low (less than 0.03 mg g^–1 dry weight). The concentrations of sucrose, fructans and hexose decreased during seed formation. If fully-developed lettuce leaves were removed from every other node at the flower bud stage, no significant differences were noted in the concentrations of sucrose, glucose, fructose, and fructans in the flower stalks of defoliated and control plants. These results suggest that sucrose and fructans are reserve carbohydrates in stems, and that accumulated sucrose and fructans are used for seed development.     

切花菊远距离运输中水势变化及预处液研发

 以切花菊‘神马’为试材,探索了远距离运输导致其花朵开放过速的原因,并通过改良切 花菊预处理液配方,延长其远距离运输后的瓶插寿命。对经模拟远距离运输又复水后的切花菊花朵和叶 片水势测定的结果表明,长时间2 ℃冷链运输后,切花菊花朵和叶片水势下降可达10 × 105 Pa。花朵的 过速开放是由瓶插复水时水势骤变导致,单位时间内水势差越大花朵开放速度越快。花枝在长途运输时 逐渐失水,增加了复水时花枝内外的水势差,致使复水时水分供应快速,促进花头花瓣快速扩展。在传 统配方基础上添加适量的N–苯基–N’–1,2,3–噻二唑–5–脲（TDZ）可减缓花朵花冠直径增长速度、 延缓叶片衰老,改良后的最佳预处液配方为：200 mg · L-1 8–羟基喹啉（8-HQ）+ 200 mg · L-1 柠檬酸（CA）+ 2 mL · L-1 聚氧乙烯–8–辛基苯基醚（Triton X-100）+ 100 mg · L-1 维生素C + 0.05 mg · L-1 TDZ + 1% 蔗糖,在实践操作中该配方使切花菊瓶插寿命比对照延长了3 d。     

Water relations and microbial proliferation in vase solutions of Narcissus tazetta L. cv. ‘Shahla-e-Shiraz’ as affected by biocide compounds

Summary

Disruption of cut flower water relations due to the growth and proliferation of microorganisms in the vase solution is one of the most important factors causing reduced vase-life and deterioration in cut flowers. These experiments were conducted to study the effects of some biocides in controlling microbial proliferation in vase solutions and on water relations in cut Narcissus tazetta L. cv. ‘Shahla-e-Shiraz’, a native bulbous cut flower of Iran. The stems of ‘Shahla-e-Shiraz’ Narcissus cut flowers were exposed to 17 treatments: aluminium sulphate (at 100, 200 or 300 mg l^–1), citric acid (at 150, 300 or 450 mg l^–1), 8-hydroxyquinoline citrate (at 200, 300 or 400 mg l^–1), sodium hypochlorite (at 400, 600 or 800 mg l^–1), calcium hypochlorite (at 400, 600 or 800 mg l^–1), sterilised distilled water, or tap water (control). Generally, the least effective compounds in controlling microbial proliferation were low concentrations of aluminium sulphate or citric acid. 8-Hydroxyquinoline citrate treatments were most effective, and the vase solution did not contain any microbes until day-6. Vase solution contaminants were yeasts, Bacillus ssp., Staphylococcus ssp., Actinomycetes and Aspergillus ssp. Yeasts and bacilli were the most common microorganisms. Severe symptoms of phytotoxicity such as bud abortion and yellowing in aluminium sulphate-treated flowers, stem proximal-end browning and shrinking in 8-hydroxyquinoline citrate-treated flowers, and bleaching of soaked parts in sodium hypochlorite treatments, were seen. Most solution was taken up in 150 mg l^–1 citric acid, while the reduction in fresh weight was least in 200 mg l^–1 8-hydroxyquinoline citrate. The correlation between microbial counts and growth rate with solution uptake was slightly negative, but their correlation with fresh weight loss was slightly positive.     

Transpiration,photosynthetic responses,tissue water relations and dry mass partitioning in Callistemon plants during drought conditions

Callistemon is an Australian species used as ornamental plant in Mediterranean regions. The objective of this research was to analyse the ability of Callistemon to overcome water deficit in terms of adjusting its physiology and morphology. Potted Callistemon laevis Anon plants were grown in controlled environment and subjected to drought stress by reducing irrigation water by 40% compared to the control (irrigated to container capacity). The drought stress produced the smallest plants throughout the experiment. After three months of drought, the leaf area, number of leaves and root volume decreased, while root/shoot ratio and root density increased. The higher root hydraulic resistance in stressed plants caused decreases in leaf and stem water potentials resulting in lower stomatal conductance and indicating that water flow through the roots is a factor that strongly influences shoot water relations. The water stress affected transpiration (63% reduction compared with the control). The consistent decrease in g_s suggested an adaptative efficient stomatal control of transpiration by this species, resulting in a higher intrinsic water use efficiency (P_n/g_s) in drought conditions, increasing as the experimental time progressed. This was accompanied by an improvement in water use efficiency of production to maintain the leaf water status. In addition, water stress induced an active osmotic adjustment and led to decreases in leaf tissue elasticity in order to maintain turgor. Therefore, the water deficit produced changes in plant water relations, gas exchange and growth in an adaptation process which could promote the faster establishment of this species in gardens or landscaping projects in Mediterranean conditions.     

A comparison of winter-sown tomato plants grown with restricted and unlimited water supply

The morphology, anatomy and physiology of winter-sown tomato plants grown with a restricted water supply (producing ‘hard’ plants) were compared with those of plants given an unlimited water supply (‘soft’ plants). The stressed plants had smaller and fewer leaves on thinner stems; the reduction in leaf area was largely due to smaller cell size. The leaves and stems also had a higher percentage dry matter; in the stems this was associated with many more and larger starch grains. It is suggested that the improvement in earliness and in fruit quality found in stressed plants originates from this increase in stored carbohydrate.

Rates of photosynthesis per unit leaf area were the same in both groups of plants when measured under laboratory conditions. The leaf cell sap had the same osmotic potential but there was a greater proportion of apoplastic water in the leaves of the stressed plants. Transpiration rates in the glasshouse were lower in the stressed plants. Possibilities for the control of plant water status to optimize early yield quantity and quality are considered.     

Photosynthetic and growth responses of juvenile Chinese kale (Brassica oleracea var. alboglabra) and Caisin (Brassica rapa subsp. parachinensis) to waterlogging and water deficit

Chinese kale (Brassica oleracea var. alboglabra) and Caisin (Brassica rapa subsp. parachinensis) are leafy vegetable crops grown in south-east Asian countries where rainfall varies dramatically from excess to deficit within and between seasons. We investigated the physiological and growth responses of these plants to waterlogging and water deficit in a controlled experiment in a glasshouse. Juvenile plants were subjected to waterlogging or water deficit for 19 days in case of Chinese kale and 14 days in case of Caisin and compared with well-watered controls. Caisin tolerated waterlogging better than Chinese kale because it produced hypocotyl roots and gas spaces developed at the stem base. In Chinese kale, waterlogging reduced plant fresh weight (90%), leaf area (86%), dry weight (80%) and leaf number (38%). In contrast, waterlogging had no impact on leaf number in Caisin and reduced plant fresh and dry weights and leaf area by 60–70%. Water deficit reduced leaf area, fresh weight and dry weight of both species by more than half. Leaf number in Chinese kale was reduced by 38% but no effect occurred in Caisin. Water deficit increased the concentration of nitrogen in the leaf dry matter by more than 60% in both species and the leaf colour of water deficient plants was dark green compared with the leaf colour of well-watered plants. Soil water deficit delayed flowering of Caisin while waterlogging accelerated it. Thickening and whitening of the cuticle on the leaves of Chinese kale probably increased its ability to retain water under drought while Caisin adjusted osmotically and Chinese kale did not. Waterlogging and water deficit had strong effects on leaf gas exchange of both Brassica species. Water deficit closed the stomata in both species and this was associated with a leaf water content of 9 g g⁻¹ DW. In contrast, waterlogging reduced conductance from 1.0 to 0.1 mol H₂O m⁻² s⁻¹ in direct proportion to changes in leaf water content, which fell from 11 to 5 g g⁻¹ DW. This separation of the effects of water deficit and waterlogging on conductance was reflected in transpiration, internal CO₂ concentration and net photosynthesis. In conclusion, Chinese kale and Caisin showed rather different adaptations in response to waterlogging and water deficit. Caisin was more tolerant of waterlogging than Chinese kale and also showed evidence of tolerance of drought. There is genetic variation to waterlogging within the Brassica genus among the leafy vegetables that could be used for cultivar improvement.     

Regulation of postharvest flower senescence in Zinnia elegans Jacq.

Postharvest decorative life of Zinnia elegans flowers was prolonged by holding-solutions containing 8-hydroxyquinoline citrate (8-HQC) and sucrose. Flowers lasted longest in a solution of 200 mg l^?1 8-HQC and 1% sucrose. Flowers held in 2 or 3% sucrose and 200 mg l^?1 8-HQC developed necrotic lesions on ray florets and foliage. The decorative life of flowers held in 0.25 or 0.5% sucrose and 200 mg l^?1 8-HQC was extended beyond those in de-ionized water, but this extension was less than, or equal to, the postharvest life of those in 1% sucrose and 8-HQC (200 mg l^?1), depending on the cultivar. Postharvest life of flowers produced in May — June under natural photoperiod was significantly longer than that of flowers produced during February to April under a 14-h day provided by incandescent light.     

Growth and photosynthetic characteristics of blueberry (Vaccinium corymbosum cv. Bluecrop) under various shade levels

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 (A_n). The maximum A_n 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 (g_s) 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 g_s 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.     

Copper distribution and ionic form effects for postharvest treatments of cut Acacia holosericea stems

A short postharvest life is the major constraint associated with cut Acacia flowers and foliage. Treatment with CuSO₄ (Cu²⁺) has previously been shown to improve the longevity of cut Acacia holosericea stems. Towards refining the treatments, a range of Cu²⁺ and Cu⁺ salts were assessed for relative efficacy in improving vase life and water relations of A. holosericea. Five hour pulses with the Cu²⁺ salts CuSO₄, CuCl₂, (CH₃COO)₂Cu and Cu(NO₃)₂ at 2.2 mM gave equally longer vase lives by ∼2.5-fold over deionised water (DIW) and standard tap water (STW) controls. The same Cu²⁺ salts at 0.5 mM in the vase solution also gave significantly (P < 0.05) improved vase life, relative fresh weight and water uptake compared to the DIW control. For Cu²⁺ versus Cu⁺, optimum concentrations with Cu²⁺ could not be directly compared due to the low solubility of the Cu⁺ salt CuCl. However, Cu⁺ from CuCl at 0.415 mM also had positive effects on vase life compared to the DIW control. Thus, both Cu²⁺ and Cu⁺ treatments can enhance vase life parameters for cut A. holosericea foliage. The benefits were irrespective of the counter ion and, thus, Cu²⁺ and Cu⁺per se were responsible. The most effective Cu²⁺ pulse treatment decreased stomatal conductance of phyllodes initially, but did not cause sustained stomatal closure. Cu accumulated to greater levels in basal stem and phyllode tissues than in upper stem and phyllode tissues of cut A. holosericea stems. Possible mechanisms of Cu²⁺/Cu⁺ action are discussed.     

Chlorocholine chloride application effects on photosynthetic capacity and photoassimilates partitioning in potato (Solanum tuberosum L.)

Treatment of potato (Solanum tuberosum L.) with chlorocholine chloride (CCC) applied twice as a foliar spray 25 and 30 days after planting has shown to decrease shoot and stolon growth but increase tuber yield. However, the regulatory role of CCC on translocation of recently fixed photoassimilates into different parts of potato plants has not been fully illustrated. In this study, ¹⁴C-isotope labelling technique was used to estimate the photosynthetic capacity and photoassimilate partitioning among leaves, stems, roots + stolons, and tubers of potted potatoes treated with 1.5 g l⁻¹ CCC. CCC treatment significantly increased tuber dry mass but reduced leaf dry mass. CCC-treated leaves had significantly higher chlorophyll and carotenoid contents and assimilated 22.0% more ¹⁴CO₂ per leaf dry mass than the controls. Compared with the control, CCC treatment reduced the translocation of ¹⁴C-photoassimilates into leaves, stems and roots + stolons but increased that into tubers. CCC-treated leaves exported 14.6% more ¹⁴C-photoassimilates into other parts of the plants. In addition, CCC treatment reduced ¹⁴C-soluble sugar and ¹⁴C-starch accumulation in leaves and stems but enhanced them in tubers and roots + stolons. Collectively, the results indicate that CCC treatment significantly improves the photosynthetic capacity of potato leaves and promotes photoassimilates partitioning into tubers thereby enhancing tuber growth.     

The effect of preservatives on water balance in cut clematis flowers

A positive water balance is crucial for longevity of cut shoots. When water loss by transpiration exceeds water uptake by cut flowers, wilting symptoms appear. Clematis is a very attractive plant which can be used as a cut flower provided that suitable cultivars are chosen. The vase life of four cultivars tested ranged between 6.7 days and 9.0 days and the standard preservative – 200 mg·dm^?3 8-hydroxyquinoline citrate (8HQC) plus 2% sucrose – prolonged it significantly in two cultivars, while 8HQC alone was efficient in only one. The preservatives delayed reduction in fresh weight. An enhancement of water uptake by the preservatives resulted in prolonged vase life of flowers in two cultivars. However, the effect of preservatives on transpiration was not related to longevity. In addition, longevity did not depend on the xylem vessel size: the cultivar with the longest vase life had the lowest average xylem vessel diameter while the cultivar with the largest vessels had an intermediate vase life. Preservatives did not always affect the number of blockages in xylem appearing during vase life. Generally, the effects of preservatives on the elements of water balance in cut shoots of clematis were not directly related to the postharvest longevity.