The effect of light,darkness and temperature on micropropagation of the pear rootstock BP10030

There was no effect of irradiance level on surviving percentages of shoot tip explants of the pear rootstock BP10030, but low irradiance stimulated the initial growth of the explant. Irradiance had a strong effect on shoot multiplication. With an increase in photosynthetic photon flux (PPF) from 10 to 80 μmol m^?2s^?1, shoot number and length and shoot fresh and dry weights increased. The greatest number of shoots and the longest ones were obtained with a 16 h photoperiod, while the highest fresh and dry weight of shoots were produced with a 24 h photoperiod. Rooting percentage and the number of roots were markedly promoted under 80 μmolm^?2s^?1 PPF. Photoperiods of 8, 16 and 24 h produced similar effects on rooting percentages and the numbers of roots. Four to seven days of darkness were the optimum for rooting. Rooting percentage and the number of roots increased with increased temperature during darkness between 5 and 25°C. A further increase in dark temperature up to 30°C reduced rooting percentage and root number.     

Effect of substrate,medium composition,irradiance and ventilation on jojoba plantlets at the rooting stage of micropropagation

The effect of substrate, medium composition, irradiance and ventilation on rooting percentage, and root morphology and functioning with respect to mineral uptake was investigated in jojoba [Simmondsia chinensis (Link) Schneider]. Plantlets grown on Sorbarod plugs embedded in perlite accumulated more biomass and showed better rooting than plantlets grown on Sorbarod plugs embedded in agar. In plants grown on the latter substrate, the addition of sucrose to water or salts media promoted rooting and accumulation of shoot and root biomass. On perlite, rooting was high in all treatments, while root growth was enhanced only by 2% sucrose. Sucrose and irradiance had a positive synergistic effect on plantlet growth. Doubling the irradiance from 58 to 116 μE m⁻² s⁻¹ and using high ventilation (22-mm membrane) failed to improve rooting but promoted the ability of the stomata to close, thereby reducing water loss under ambient conditions. High irradiance and ventilation lowered the chlorophyll content, but without impairing biomass accumulation. Plantlets grown under enhanced ventilation and 0.5% sucrose formed fine roots within the cellulose plug and thick roots on the vessel floor. With the 2% sucrose supplementation, the roots were generally thicker, with very few thin roots being formed. ³⁶Cl uptake into plantlets and transport to the leaves decreased in plants exposed to a high sucrose concentration. Acclimatization of jojoba plantlets was improved by enhancing ventilation.     

Interaction of stock plant irradiance and auxin in the propagation of apple rootstocks by cuttings

The purpose of the investigation was to examine the effects of different irradiances (light intensities: 8, 16, 38, 54 W/m²) to stock plants on the subsequent rooting of cuttings taken from these stock plants.If the cuttings were rooted without treatment with auxin (indole butyric acid), there was no difference in rooting attributable to the irradiance pretreatments. Auxin treatment of the cuttings was most effective in increasing root numbers and rooting-percentage in cuttings taken from stock plants grown under 8 W/m².     

Aluminium-induced effects on growth,morphogenesis and oxidative stress reactions in in vitro cultures of quince

The effects of Al³⁺ [supplied as Al₂(SO₄)₃·18H₂O] addition to culture media (pH 4.0) on growth, morphogenesis (in leaf explants), and oxidative stress reactions in in vitro cultures of ‘BA 29’ quince were investigated. Aluminium (Al 0.5 mM) strongly inhibited shoot growth in the proliferation and rooting phases (Al 2.2 mM), reduced shoot proliferation (Al 1.1 mM), and induced tissue browning. Superoxide dismutase (SOD) activity was increased in shoot cultures supplemented with 2 mM Al. Malondialdehyde (MDA) content of shoots was strongly increased by Al during proliferation (starting from Al 1.7 mM) and rooting (already at Al 1.1 mM), thus serving as a good ‘marker’ for Al toxicity. Even a low concentration of Al (0.5 mM) in the shoot induction medium was found to inhibit shoot regeneration. When standard (Al 0) shoot induction medium was used, leaf explant growth was only reduced by 2.2 mM Al in the subsequent growth phases. Following a preliminary selection for their growth on Al-enriched media, 82 potentially Al-tolerant quince somaclones were selected for further trials.     

Black Currant Leaf Spot: II. Laboratory Tests of Fungicides for the Prevention of Sporing of Pseudopeziza Ribis on Overwintered Leaves

Summary

We have developed a two-step procedure for rooting of tea microshoots in vitro. The effectiveness of different auxin treatments for root formation was found to differ. Among the auxins tested, 25 μM -naphthalene acetic acid (NAA) gave the best results, with 100% rooting, compared to 25 μM indole-3-butyric acid (IBA) or 25 μM indole-3-acetic acid (IAA), which induced 17% and 58% rooting, respectively. Incubation of tea microshoots on 0.33 Murashige and Skoog (MS) medium, supplemented with 25.0 μM NAA or 175.0 μM IBA for 10 d, followed by transfer to auxin-free 0.33 MS medium resulted in 100% rooting, whereas 50.0 μM IAA induced 91.7% rooting. Besides the different auxin treatments, the strength of the MS medium, the duration of incubation of microshoots in auxin-containing medium, the sucrose concentration, the gelling agent, the pH of the medium, the incubation temperature, the light intensity, and the quality of the shoots also played a significant role during in vitro rooting of micropropagated tea shoots. Among the combinations tested, the most effective results were obtained when green microshoots were incubated on 0.33 MS medium supplemented with 25.0 μM NAA, 50.0 mM sucrose, pH 5.5, gelled with 0.2% (w/v) Phytagel^TM for 10 d at 25° – 30°C at a light intensity of 40 μmol m^–2 s^–1, followed by transfer of shoots to auxin-free 0.3 MS medium. This resulted in 100% rooting and, on average, 11 long roots were formed per shoot. Anatomical changes during adventitious rooting of micropropagated tea shoots in vitro were also studied to understand the process of rooting.     

Effects of light intensity and light quality on the obligate shade plant Aglaonema commutatum. II. Photosynthesis and dry-matter partitioning

The introduction of Aglaonema commutatum as an ornamental plant has been an empirical process. The success reached seems due to the capacity of the species to grow in very low light intensities for long periods. The results obtained have shown: (1) the light- saturated photosynthetic rate was very low even for shade plants (0.7-1.0 (μmol m^-2s^-1), (2) growth at the lowest irradiance did not stop despite a negative net CO₂ exchange. The growth of new leaves was sustained by reserves stored in the cutting, (3) the plants grown at the lowest irradiances showed a decrease in light-saturated photosynthetic rate and a change in dry-matter partitioning with poor growth of root systems, and (4) the responses were influenced more by light intensity than by light quality.     

Nitrogen content determines adventitious rooting in Euphorbia pulcherrima under adequate light independently of pre-rooting carbohydrate depletion of cuttings

Root regeneration in shoot tip cuttings responds to graduated nitrogen (N) fertilization of stock plants. In pelargonium cuttings, reduced carbohydrate reserves caused by high N absorption by the donor plants and post-harvest storage of cuttings limit adventitious root formation, especially in low-light environments. In contrast, in chrysanthemum, similar carbohydrate reserves do not have this dominant effect on rooting capacity. The positive correlation between rooting capacity and internal N status is stable across a wide range of environments and is genotypically consistent for this species. However, the influence of N and carbohydrates on adventitious rooting of Euphorbia pulcherrima is unknown. We investigated the consequences of different N fertilization regimens applied to E. pulcherrima stock plants and cold and dark storage of the cuttings on N absorption, carbohydrate distribution, and rooting capacity of cuttings. Increasing time of stock plant cultivation with graduated N nutrition produced cuttings with N contents, ranging from 19 to 51 mg N g⁻¹ dry mass (DM). High N absorption resulted in low carbohydrate concentrations in cuttings, and subsequent storage decreased carbohydrate concentrations further, particularly in stems. Lower sucrose contents in leaves were correlated with reduced rooting of stored cuttings at a particular harvest date. However, despite the lower carbohydrate levels, root numbers and lengths correlated positively with internal N concentrations. These relationships remained stable in unstored and stored cuttings, even when overall rooting intensity was reduced under lower natural light during autumn. Multivariate regressions accounting for nitrogen content, sucrose content and daily light integral during rooting highlighted these relationships and explained up to 79% of rooting variances. We conclude N nutrition of stock plants and N absorption by cuttings are the dominant factors determining the rooting capacity of poinsettia when rooting occurs under sufficient light, as is commonly available during propagation. To maximize rooting capacity of poinsettia cuttings their nitrogen content should exceed a threshold of 40 mg N g⁻¹ DM.     

In vitro shoot proliferation and enhancement of rooting for the large-scale propagation of yellow bamboo (Bambusa vulgaris ‘Striata’)

Continuous and rapidly proliferating axillary shoots were raised from axillary buds in secondary branches of adult field culms and nursery grown 1-year-old tissue culture-raised plants of Bambusa vulgaris ‘Striata’. Shoots continuously proliferated in a MS medium containing 4 mg L⁻¹ 6-benzyladenine (BA). The effects of indole butyric acid (IBA) levels, a pretreatment with thidiazuron (TDZ) (1-phenyl-1-([1,2,3-thidiazol-5-yl])urea) and illumination on rooting, were investigated after 6 months of shoot proliferation. A rooting medium with IBA at 3 mg L⁻¹ was optimum for root induction. Shoots of adult field culms that were proliferated in the presence of BA when induced to root in this medium resulted in 40% rooting in 27 days. In vitro shoots raised from 1-year-old tissue cultured plants showed 92% rooting under the same conditions. Rooting was enhanced when the relatively difficult-to-root in vitro shoots from adult field culms were pretreated with 0.5 mg L⁻¹ TDZ for two to three subcultures before placing in the root induction medium. Continuously illuminated shoots pretreated with TDZ for three subcultures showed 100% rooting compared to 83% rooting of shoots that were exposed to a 12 h photoperiod. These findings have been applied in the large-scale propagation of this species.     

Micropropagation of red raspberry and the influence of phloroglucinol

Micropropagation of 12 raspberry seedling selections and the cultivar ‘Malling Jewel’ has been achieved. A basic culture medium (Linsmaier and Skoog, 1965) supplemented with benzylaminopurine (BAP), 1.0 mg l^?1, and indol-3-yl butyric acid (IBA), 0.1 mg l^?1, was optimal for shoot proliferation. The presence of phloroglucinol (PG) at a concentration of 162 mg l^?1 significantly increased shoot number at all auxin: cytokinin concentrations. Removal of the cytokinin and increasing the concentration of IBA to 1.0 mg l^?1 resulted in adventitious root formation. PG synergistically promoted the number of roots per rooted culture but did not significantly increase the percentage rooting. Viable plants were produced from all genotypes when transplanted to soil.     

Rooting of chrysanthemum cuttings. Influence of irradiance during stock plant growth and of decapitation and disbudding of cuttings

Stock plants of Chrysanthemum morifolium Ramat. cultivar ‘Improved Mefo’ were grown in a controlled-environment room at different levels of irradiance (9, 23, 53 or 90 W m^?2). After 3 weeks, cuttings were excised and rooted for 3 weeks at an irradiance of 16 W m^?2. Cuttings from stock plants grown at the highest irradiance had the highest number of roots, while cuttings from the lowest irradiance had the lowest number of roots.The importance of the presence of shoot meristems for root formation was investigated through disbudding and decapitation at different times after the excision of the cuttings. Removing the buds on the day of excision had no effect on the number of roots formed, while the removal of the buds on day 2 to day 5 after excision had a promotive effect. Removal later than 7 days after excision had no effect at all.The results are discussed from the point of view that an interaction between nutritional and hormonal factors regulates the process of root formation.     

The effect of nitrogen source and concentration,medium pH and buffering on in vitro shoot growth and rooting in Eucalyptus marginata

This work examined the effect of nitrogen source and medium buffering on the micropropagation of Eucalyptus marginata Donn ex Sm. The number of shoots was increased when media contained 2-(N-morpholino) ethanesulfonic acid (MES) but this increase was minor and only applied to one of the two clones tested. Highest root production was obtained when the medium contained 7.5 mM nitrogen in a ratio of 2NO₃⁻:1NH₄⁺ and was buffered with 10 mM MES. In the rooting medium the pH was influenced most significantly by the nitrogen source, and then whether the medium was buffered. The media pH remained relatively constant when nitrate was the sole nitrogen source and this was assisted by the addition of 10 mM MES. Lower concentrations (<10 mM) of MES were less effective in buffering media over a four-week culture period in both shoot multiplication and rooting medium.     

An investigation on the effect of different plant growth regulating compounds in in vitro shoot tip and node culture of lemon seedlings

The possible application of some less commonly used in vitro growth regulating compounds is outlined. A number of treatments were applied to determine the best way of inducing in vitro shoot proliferation and rooting on a modified Driver–Kuniyuki [HortScience 19 (1984) 507] basal medium of lemon (Citrus limon (L.) Burm, f. cv. Interdonato) seedlings. 6-Benzyladenine (BA) alone (1, 2 and 4 mg l⁻¹) and in combination with either orange juice (10%, v/v), silver nitrate (3 mg l⁻¹), gibberellic acid (GA₃) (0.1 mg l⁻¹ at the establishment stage and 0.5 mg l⁻¹ at all combinations during the proliferation stage) or abscisic acid (ABA) (0.2 mg l⁻¹ only at the establishment stage) were used to stimulate shoot formation during the establishment and the proliferation stage. The combination of BA with ABA gave a high rate of shoot formation, while GA₃ and silver nitrate enhanced shoot elongation. When these shoots were transferred to the rooting stage, the effect of application of two different auxins (indole-3-butyric acid (IBA) and α-napthaleneacetic acid) was examined, as well as different methods of application (auxin added to the basal medium and auxin application by dipping the base of the explant in auxin solution). Dipping the base of the explants in a 50% ethanol solution of IBA at 1000 mg l⁻¹ for 5 s resulted in 80% rooting with subsequent 90% survival of these explants, during acclimatization under mist.     

Clonal propagation of Rosa clinophylla Thory. through axillary bud culture

A protocol for clonal propagation of Rosa clinophylla, a rare and endangered species but very important for breeding purposes had been standardized through in vitro axillary bud culture. Although cytokinins alone were able to induce shoot buds, but their proper growth and number could be increased only when they were used in combination with GA₃. However, there was shoot tip necrosis and leaf fall in the proliferated shoots. AgNO₃ at 58.85 μM proved effective to avoid shoot necrosis and yellowing of leaves. Activated charcoal (AC) at 250 mg l⁻¹ was found necessary at all the stages of shoot multiplication as well as rooting. Ninety percent rooting could be achieved in 1/2 MS medium supplemented with 4.92 μM IBA and 250 mg l⁻¹ AC. Rooted plantlets were hardened and transferred to the field successfully with 80% survival rate.     

Root shoot interactions in passionfruit (Passiflora sp.) under the influence of changing root volumes and soil temperatures

Summary

Passionfruit are grown in the tropics and subtropics where mean monthly soil temperatures at 15 cm range from about 10° to 30°C. The choice of rootstock can also influence production with most industries exploiting either the purple (Passiflora edulis f. edulis) or golden passionfruit (P. edulis tflavicarpa). We examined the relationship between shoot and root growth in purple x golden hybrid E-23 grafted onto golden passionfruit seedlings. Growth was manipulated by varying the volume of the soil available to the roots or temperature of the root zone. Shoot and root growth increased as root zone volume increased from 0.3, 1.4, 4, 12 to 24 1. Shoot weight (W_s) was correlated with root weight (W_R):W_S = 12.697 + 5.272 W_R + 0.195 W_R² (r² = 91%, P<0.001), with the plants allocating a smaller proportion of dry matter to the roots as root weight increased. Differences in shoot growth with pot volume were not due to changes in water or nutrient status. In the temperature experiment, the two critical root zone temperatures at 90% of maximum growth were about 20° and 35° C for vine extension, leaf area, node and leaf production, and 20° and 30°C for flower production. Leaf and stem dry weight were optimal between about 18° and 34°C, while maximum root growth occurred at 38°C. There was a weak relationship between shoot (W_s) and root dry weight (W_R): W_s = ?19.346 + 24.500 W_R ?1.046 W_R² (r² = 53%, .P<0.001). Apparently, variations in shoot growth at different soil temperatures cannot be explained solely by differences in root growth. Reduced growth at 10°C was associated with lower chlorophyll concentration, stomatal conductance and net CO₂ assimilation, but not lower leaf water potential. The concentration of most nutrients were lower at 10°C than at higher temperatures, but none was outside the range which would be expected to restrict growth. There appears to be a co-ordination of shoot and root growth as the soil volume available for root growth increases, whereas root temperature affects the roots and tops differently. The results of the pot volume experiment demonstrate the importance of rootstock vigour in passionfruit breeding. Productivity would be affected in cool subtropical areas with soil <20°C and in tropical areas with soil >30°C.     

Salinity and shading effects on leaf water relations and ionic composition of strawberry plants grown on rockwool

Summary

Strawberry plants were grown in rockwool under glasshouse conditions at NaCl salinities of 2.6,5.9 and 8.6 mS cm^-1 and at total irradiances of 2.1 and 4.9 MJ m^?2d^?1. Increasing salinity and irradiance reduced leaf water potential (ψω), osmotic potential (ψπ) and turgor potential (ψτ). There was an interaction between salinity and irradiance on with the lowest ψπ recorded for the unshaded leaves. Increased salinity altered the ionic composition of the leaf. Chloride concentration was increased from 0.03 to 0.61 % (D.W.) while NO₃ content in the leaf sap was reduced from 10.51 to 3.60 mg ml^-1 as salinity increased from 2.6 to 8.6 mS cm^?1. Expressed on a fresh-weight basis, the concentration of K was reduced at high irradiance whereas Ca and Mg were enhanced. On a dry-weight basis K, Na, Ca and Mg were unaffected by salinity treatment. Net photosynthesis was reduced by high salinity but only in plants grown in unshaded conditions.     

Castanea sativa plantlets proliferated from axillary buds cultivated in vitro

Chestnut plants were proliferated in vitro from axillary buds of juvenile shoots. N6-Benzyl-aminopurine (BAP) at 0.1?0.5 mg l^?1 was optimal for shoot multiplication. The important role played by the macronutrient formula on shoot multiplication, and especially on the rooting-stage, is emphasized. The MS ($\text{1}\text{2}$ NO₃) macronutrients gave the best rooting percentage as well as the highest number of roots per rooted shoot. In these experiments, shoots remained in the 3 mg l^?1 indole-3-butyric acid (IBA) medium for 12 days, after which they were transferred to an auxin-free medium where roots developed fully. Optimum rooting was achieved by immersing the 1 cm basal end of shoots in concentrated IBA solutions (0.5?1 mg ml^?1) for periods ranging from 2 to 15 min.     

In vitro propagation of olive (Olea europea sativa L.) ‘Kalamon’

A micropropagation method is described for olive (Olea europea sativa L.) ‘Kalamon’ using single-node explants collected from shoots produced from olive ovules grown in a growth chamber. Shoot proliferation was obtained on OM modified medium supplemented with 0.5 mg r¹ cystine, 10 mg I^-1 pantothenic acid calcium, 0.5 mg I^-' gibberel- lic acid (GA₃), 0.1 mg T¹ indole-3-acetic acid (IAA) and 10 mg I^-1 zeatin riboside, or 7.5 mg I^-1 benzyladenine (BA), or 10 mg I^-1 N⁶-2-isopentenyladenine (2ip). Explants were rooted on a medium similar to that for shoot development, but without cytokinins and with a-naphthaleneacetic acid (a-NAA), and indole-3-butyric acid (IBA) at 1, 2 and 3 mg I^-1 for both auxins. a-NAA at all concentrations was more effective than IBA. Shoot proliferation and rooting were improved by the addition to the nutrient media of 20 mg I^-1 and 50 mg I^-1 crude extract from olive ovules, respectively. Rooted explants were transferred to pots containing equal volumes of peat and vermiculite; about half survived.     

Evaluation of the activity of aqueous extracts of some organic waste materials on in vitro-cultured shoots of ‘M9’ apple rootstock

Summary

The present work investigated the effects of different aqueous extracts of organic waste compounds on growth, proliferation and photosynthetic activity in ‘M9’ (Malus domestica Borkh.) shoot cultures, with the aim of determining the feasibility of using in vitro cultures as a tool for the rapid evaluation of organic amendments in agriculture. Aqueous extracts of the following organic waste compounds: cow manure (CM), sugarbeet industrial waste (SB), mixed grape, poultry and municipal solid waste (GPM), and citrus pruning and industrial waste (CPI) were prepared at a rate of 1:10 (w/v) compound:distilled water. The basal media used in the proliferation phase were: (i) PM1, modified Murashige and Skoog (MS) enriched with 4.4 µM 6-benzyladenine (BA); (ii) PM2, as PM1 but with a reduced cytokinin concentration (1 µM BA) to evaluate possible hormone effects; and (iii) PM3, 4.4 µM BA with reduced salt strength (0.33 MS) to induce nutrient deficiency. Hormone-free medium with half-strength MS salts was used for rooting. All media were enriched with each extract at 0, 0.2, 2, 20 or 200 ml l^–1. Photosynthetic activity was measured on PM3 medium enriched with SB or CM. Standard culture conditions were 22° ± 2°C, with a 16 h photoperiod at 30 µmoles photosynthetically active radiation (PAR) m^–2 s^–1, but at 80 µmoles PAR m^–2 s^–1 to determine photosynthetic activity. Shoot weight increase in PM1 was not affected by the GPM and CPI extracts, while the growth trends of CM- and SB-treated shoots were described by a second-degree function with maxima at 2 ml l^–1 and 0.2 ml l^–1, respectively. Shoot proliferation for SB was represented by a quadratic curve (maximum at 2 ml l^–1), was linearly reduced as GPM increased, but was not affected by CM or CPI. Treatments did not significantly affect rooting percentage and root length; however root number was increased by SB at 2 ml l^–1.CO₂ fixation increased linearly with both SB and CM, despite reduced growth at the highest levels of extract.     

Micropropagation of Prunus scoparia,a Suitable Rootstock for Almond under Drought Conditions

Prunus scoparia is a wild deciduous shrub, usually living on dry calcareous soils of the rocky mountains and has been used as a grafting rootstock for domesticated almonds to provide drought resistance. In the current study, micropropagation ability of P. scoparia was investigated using cytokinin and auxin. Uniform nodal shoot pieces (3–5 cm in length) of seedlings were used as explants. The explants were disinfected with 10% sodium hypochlorite solution. For adventitious shoot induction and proliferation, Murashige and Skoog (MS) media containing 7.00 g/l agar and 30.00 g/l sucrose containing five concentrations of benzyl adenine (BA) (0.00, 0.50, 1.00, 2.00, and 4.00 mg/1) and also containing six concentrations of Thidiazuron (TDZ) (0.00, 0.50, 1.00, 2.00, 5.00, and 7.00 mg/1) were compared. For rooting, in vitro shoots (2–3 cm) were transferred into ½ MS medium supplemented with 30 g/l sucrose, 7.50 g/l agar, and different concentrations of IBA (0.00, 0.25, 0.50, and 1.00 mg/l) and NAA (0.00, 0.25, 0.50, and 1.00 mg/l). Based on the results obtained for shoot proliferation, only 2.00 and 4.00 mg/l BA and 2.00 mg/l TDZ concentrations generated shoots, while other treatments did not show shoot proliferation. Among the three treatments that generated shoots, the best results for shoot number, leaf number, and leaf color quality were observed in media containing 2.00 mg/l TDZ. Based on the results obtained for rooting, the effect of IBA concentrations on the rooting percentage, root number, and root length was significant. Among IBA concentrations, only 0.50 mg/l IBA induced rooting, while there was no rooting in the media containing other IBA concentrations. None of the NAA concentrations showed rooting. In conclusion, MS culture medium supplemented with 2.00 mg/l TDZ and ½ MS culture medium supplemented with 0.50 mg/l IBA are suggested for in vitro shoot proliferation and rooting of P. scoparia, respectively. The results presented herein could be used for in vitro selection and micropropagation of P. scoparia.     

苹果优良矮砧S_(18)、s_(20)微茎尖脱毒组织培养技术研究

通过对武乡海棠(Malus honanensis Rehd.)优良矮砧S_(18)、S_(20)两个单系的0.2mm微茎尖脱毒组织培养技术研究,解决了微茎尖切割、接种、分化及生根移栽等一系列技术难题,获得了S_(20)、S_(18)一批脱毒试管苗及移栽壮苗.分化数分别达2.0和3.6,生根率达76.1%和90.0%,平均根长2cm以上,平均根数5条,移栽成活率达78%.