Zeatin-induced one-step in vitro cloning affects the vegetative growth of cranberry (<Emphasis Type="Italic">Vaccinium macrocarpon</Emphasis> Ait.) micropropagules over stem cuttings

Shoot proliferation and rooting of three cranberry (Vaccinium macrocarpon Ait.) cultivars Bergman, Pilgrim, and Stevens were obtained in vitro on a modified nutrient medium containing zeatin following a one-step procedure. Bergman and Stevens differed in terms of shoot height, leaf number per shoot, rooting frequency, root number per explant, and root length; this was manifested with various concentrations of zeatin. Shoots proliferated and roots developed best when nodal segments were cultured in the medium supplemented with very low concentration of zeatin (2–4 μM). Such zeatin-induced tissue culture (TC) shoots of Bergman, Pilgrim, and Stevens were rooted ex vitro and compared with those propagated by conventional softwood cuttings (SC) for growth and morphology over four growth seasons. Significant interactions for leaf number per upright were observed among the treatments. The cultivars differed in terms of runner number per plant, upright length, number of leaves per upright, and shoot vigor. The propagation method had an effect on morphology of cranberry plants. The TC plants produced more runners and uprights with more leaves per upright than the conventional cuttings. This increase in vegetative growth of in vitro-derived plants over stem cuttings varied among genotypes. In vitro culture on zeatin-containing nutrient medium apparently induces the juvenile branching characteristics that favored enhanced vegetative growth with more shoots and leaf production.     

Adventitious rooting of conifers: influence of physical and chemical factors

In conifers, vegetative propagation of superior genotypes is the most direct means for making large genetic gains, because it allows a large proportion of genetic diversity to be captured in a single cycle of selection. There are two aims of vegetative propagation, namely large-scale multiplication of select genotypes and production of large numbers of plants from scarce and costly seed that originates from controlled seed orchard pollinations. This can be achieved, in some species, either through rooted cuttings or rooted microshoots, the latter regenerated through tissue culture in vitro. Thus far, both strategies have been used but often achieved limited success mainly because of difficult and inefficient rooting process. In this overview of technology, we focus on the progress in defining the physical and chemical factors that help the conifer cuttings and microshoots to develop adventitious roots. These factors include plant growth regulators, carbohydrates, light quality, temperature and rooting substrates/media as major variables for development of reliable adventitious rooting protocols for different conifer species.     

Application of Ectomycorrhizal Fungi in Vegetative Propagation of Conifers

In forestry, vegetative propagation is important for the production of selected genotypes and shortening the selection cycles in genetic improvement programs. In vivo cutting production, in vitro organogenesis and somatic embryogenesis are applicable with conifers. However, with most coniferous species these methods are not yet suitable for commercial application. Large-scale production of clonal material using cuttings or organogenesis is hindered by rooting problems and difficulties in the maturation and conversion limit the use of somatic embryogenesis. Economically important conifers form symbiotic relationship mostly with ectomycorrhizal (ECM) fungi, which increase the fitness of the host tree. Several studies have shown the potential of using ECM fungi in conifer vegetative propagation. Inoculation with specific fungi can enhance root formation and/or subsequent root branching of in vivo cuttings and in vitro adventitious shoots. Germination of somatic embryos and subsequent root growth can also be improved by the use of ECM fungi. In addition, inoculation can increase the tree's ability to overcome the stress related to ex vitro transfer. A specific interaction between a fungal strain and tree clone occurs during root induction and germination of somatic embryos. Multiple rooting factors exist in this interaction that complicate the predictability of the response to inoculation. Fungal-specific factors that influence rooting responses to inoculation may include plant growth regulator production, modification of the rooting environment, and interactions with beneficial microbes. A combination of these factors may act synergistically to result in positive responses in tree genotypes that are compatible with the fungus.     

Roles of leaf in regulation of root and shoot growth from single node softwood cuttings of grape (Vitis vinifera)

The role of leaf in regulation of root and shoot growths in single node softwood cuttings of grape (Vitis vinifera) was characterised. Leafy cuttings showed early rooting, vigorous root growth and subsequent shoot development. Defoliation at planting induced early sprouting, but adversely affected rooting and decreased the survival of cuttings irrespective of pre‐planting treatment with 100 μM indole 3‐acetic acid (IAA). Treatment with IAA did not affect the percent rooting of leafy cuttings but increased root and shoot growth. Leaf weight (wt) and leaf area of the cuttings showed a highly significant correlation to root wt of the new plant at 4 wk after planting, while cutting stem + petiole wt was either not or less significantly correlated to root and shoot weights of the subsequent plant. The greater the area or wt of leaf, the better the root and shoot growths, implying that leaf contributed to adventitious root growth. However, retaining the leaf for just 2 days was enough to stimulate rooting in more than 80% of the cuttings, suggesting that leaf tissue could also induce root formation. Root growth increased with the period of leaf retention but leaf removal before 3 wk triggered sprouting leading to high mortality in rooted cuttings. Bringing the leaf closer to the rooting zone by preparing leaf at base (LAB) cuttings delayed rooting and sprouting compared with the standard leaf at top (LAT) cuttings. An inhibitory effect on rooting and sprouting by the exposed upper internode region in LAB cuttings is suggested.     

长白落叶松插穗的内源激素水平及其与扦插生根的关系

长白落叶松 (Larixolgensis)扦插繁殖的试验结果表明 ,嫩枝扦插效果好于硬枝扦插 ,并且母树年龄是影响其扦插生根的重要因子。母树年龄为 2年生时 ,生根率达 95 %以上。本文在此试验的基础上 ,对嫩枝和硬枝插穗中内源植物激素水平进行了测定。结果发现嫩枝插穗中IAA、CTKs的含量要高于硬枝插穗中IAA、CTKs的含量 ,并且随母树年龄的增加而降低 ;相反 ,嫩枝插穗中ABA含量要低于硬枝插穗中ABA的含量 ,并且随着母树年龄的增加而增加。实验结果表明 :IAA、ABA的含量和扦插生根有密切关系。IAA促进生根 ,ABA抑制生根。IAA/ABA比值可以用来衡量长白落叶松的生根能力     

Vegetative Propagation of Pinus sylvestris

Methods for the vegetative propagation of Pinus sylvestris L. from interfascicular shoots are described. Using 5-year-old plants the outgrowth of interfascicular shoots was promoted by removal of terminal and lateral buds; this response was augmented substantially by application of cytokinin, tri-iodobenzoic acid, alar and morphactin alone and especially in combination. The rooting capacity of shoot cuttings from interfascicular shoots appeared to be largely determined by the state of growth of the stock plant. Cuttings from dormant stock plants subjected to short-day treatment followed by a period of low temperature gave the best rooting, especially when the cuttings themselves had been cold-stored prior to planting. Rooting was optimal when such cuttings were treated with a mixture of 25 mg/l of indolebutyric acid and 25 mg/l of napthaleneacetic acid as a 48 h basal soak, and were planted on a heated mistbench under extended illumination; over 90% of such cuttings could be rooted. These results are discussed in relation to bud activity, endogenous hormone levels and promoting tissue extracts also tested.     

In vitro propagation of Vicia faba L. by micro-cutting and multiple shoot induction

The influences of nitrogen sources, culture temperature and activated charcoal supplements were studied in relation to the rooting ability of V. faba cuttings. The interaction of these factors led to quantitative and qualitative modifications of the culture responses. Low temperatures (14–18°C) were suitable for in vitro culture, limiting the formation of phenolics in plant material and making activated charcoal supplement unnecessary. Nitrogen supplements contributed in modifying the different plant responses, in accordance with temperature. Multiple shoot formation was obtained from the cotyledonary node and from the stem nodes cultivated in the presence of 6-benzylaminopurine (BAP). BAP at 4 mg l^-1 was the most effective concentration in promoting high rates of shoot development. The original position of stem nodes was found to determine the explant response to plant growth regulator treatments, possibly due to the effect of residual apical dominance.     

Effect of auxins on adventitious rooting from stem cuttings of candidate plus tree Pongamia pinnata (L.), a potential biodiesel plant

Pongamia pinnata, commercially important tree species used to produce biofuels, is known for its multipurpose benefits and its role in agro-forestry. Present study examines the amenability of vegetative propagation and effect of maturation in candidate plus tree P. pinnata through rooting of stem cuttings treated with varying concentrations and combinations of auxins. The performance of the cuttings was evaluated using SAS GLM software and the data were analyzed as a one-way classified data with and without sub sampling for inferring auxin concentration that can be included in programmes aimed at genetic improvement of the tree species. All auxin treatments promoted sprouting and at lower concentrations triggered/enhanced rooting of cuttings. The effectiveness was in the order of IBA > NAA > IAA when applied singly. IBA at 4.92 mM was found to be most effective where rooting percentage and number of roots were significantly higher (P < 0.01) than in control. However higher concentrations of auxins above 7 mM in general inhibited the rooting of cuttings. The interaction among auxins was found to be effective in root induction and differentiation and the most stimulating effects were observed in three-component mixture. The effect of other cutting characteristics such as juvenility and cutting position on rooting is also discussed.     

The effect of etiolation and shading of stock plants on rhizogenesis in stem cuttings of <Emphasis Type="Italic">Cotinus coggygria</Emphasis>

In order to improve vegetative propagation of a difficult to root Cotinus coggygria the stock plants were subjected to: etiolation, shading and spraying with IBA, combined with the application of two commercially available rooting powders. The IBA treatment was more suitable for rooting of C. coggygria cuttings than the NAA application and it enhanced rhizogenesis regardless of the form of auxin application (foliar application to a stock plant or a rooting powder used directly on cuttings) and the amount of light provided to stock plants. Etiolation did not improve rhizogenesis in stem cuttings, however, reduction of light intensity by 50% and 96% of the ambient prior to harvest of cuttings affected rooting positively. Positive effects of shading can be ascribed to changes in shoot anatomy, i.e. a weaker sclerenchyma development. Synergistic effect of shading and foliar auxin application can result from the increase in leaf blade area and/or thinner lower epiderm. Enhanced rooting in cuttings from shoots grown out under reduced light intensity was accompanied by decrease in the contents of total soluble sugars, soluble proteins and free ABA and by increase in total chlorophyll, free amino acids, polyphenolic acids and free IAA contents.     

Rooting cuttings of<Emphasis Type="Italic"> Syringa vulgaris</Emphasis> cv. Charles Joly and<Emphasis Type="Italic"> Corylus avellana</Emphasis> cv. Aurea: the influence of stock plant pruning and shoot growth

The relationship between shoot growth and rooting was examined in two, 'difficult-to root' amenity trees, Syringa vulgaris L. cv. Charles Joly and Corylus avellana L. cv. Aurea. A range of treatments reflecting severity of pruning was imposed on field-grown stock prior to bud break. To minimise variation due to the numbers of buds that developed under different treatments, bud number was restricted to 30 per plant. Leafy cuttings were harvested at different stages of the active growth phase of each species. With Syringa, rooting decreased with later harvests, but loss of rooting potential was delayed in cuttings collected from the most severe pruning treatment. Rooting potential was associated with the extent of post-excision shoot growth on the cutting but regression analyses indicated that this relationship could not entirely explain the loss of rooting with time, nor the effects due to pruning. Similarly, in Corylus rooting was promoted by severe pruning, but the relationship between apical growth on the cutting and rooting was weaker than in Syringa, and only at the last harvest did growth play a critical role in determining rooting. Another unusual factor of the last harvest of Corylus was a bimodal distribution of roots per cutting, with very few rooted cuttings having less than five roots. This implies that, for this harvest at least, the potential of an individual cutting to root is probably not limited by the number of potential rooting sites.     

Endogenous Levels of Growth Regulators and Their Relationship to the Rooting of Dahlia Cuttings

The relationship between the level of endogenous growth regulators and the rooting ability of dahlia cuttings was investigated. Easy-to-root vegetative cuttings were compared with difficult-to-root, flower bud bearing cuttings and the easy-to-root cv. Choot Hashani was compared with the difficnlt-to-root cv. Orpheo. No differences in the level of extracted or diffusable auxin, nor in the level of rooting cofactors, were found between easy-to-root and difficult-to-root cuttings. No activity could be found at the R_f zone corresponding to Cofactor 4 which is considered the main rooting cofactor in other plants. Higher inhibitor activity levels (assayed by the wheat coleoptile test and the mung bean rooting test) were found in difficult-to-root than in easily rooted cuttings. Furthermore, the inhibitor activity level in exadates from decapitated plants, was higher in esodates from plants which bore difficult-to-root cuttings than from plants bearing easy-to-root ones. Grafting of an easy-to-root plant onto a difficult-to-root stock caused inhibition of rooting in the cuttings taken from the scion. Results suggest that inhibitors formed in the root system, move upwards and accumulate in the plant, there causing the inhibition of rooting. Evidence from chromatographic comparisons and exogenous treatments with ABA indicate that the main inhibitor involved in the inhibition of rooting in dahlia cuttings is not ABA.     

Improving propagation methods of Ricinodendron heudelotti Baill. from cuttings

Ricinodendron heudelotii is a valuable multipurpose tree from Africa that is lacking an efficient and inexpensive vegetative propagation method. To improve multiplication, a series of nursery experiments were conducted to assess the effect of propagation media, plant growth regulators (NAA and IBA), accession source harvest timing, cutting type, and pre-treatment with honey. Maximum survival and rooting percentages of 90.2 and 93.7% respectively were achieved in all experiments. The maximum number of leaves and roots were respectively, 7.4 and 8.7; maximum root length was 15.6 cm. Fine sand was superior to sawdust or fine sand:sawdust mixture. IBA, at 100 μg/l was more effective than NAA for rooting and growth. Principal component analysis showed that, independent of the accession source, cuttings harvested from April to May were more suitable for propagation, giving the highest rates of rooting and growth. In contrast, variable results were achieved with apical cuttings (highest rooting), basal single-node leafy cuttings (highest number of leaves and length of root) and basal two-node leafy cuttings (highest number of roots). Cuttings were more successful when they were soaked in honey for 60 min. After acclimatization, maximum survival rate of plants was 67.6%. This improved protocol can be incorporated into agro forestry system in which propagation of R. heudelotii is a component.     

In vitro propagation of Halesia carolina L. and the influence of explantation timing on initial shoot proliferation

Halesia carolina L., a small, ornamentally valuable tree, is difficult to propagate due to the complexity of seed propagation and the unavailability of propagules for conventional vegetative propagation. A micropropagation system was developed to facilitate easy propagation of this species. Actively growing shoot tips achieved optimum shoot proliferation from axillary buds when placed on Woody Plant Medium supplemented with 1.0 to 2.5 mg/l benzyladenine. The addition of 0.1 mg/l naphthaleneacetic acid had little effect on culture performance. Murashige and Skoog medium was incapable of supporting vigorous shoot proliferation. Non-sterile rooting conditions provided better rooting and subsequent plantlet growth, when compared to an in vitro rooting method. The seasonal fluctuations in the stock plant dramatically affected the shoot proliferating potential of the explants in vitro. Rapidly elongating shoots formed shoot proliferating cultures more slowly than explants taken either before or after the rapid elongation phase.     

Adventitious rooting of conifers: influence of biological factors

Vegetative propagation of superior conifer trees can be achieved, e.g., through rooted cuttings or rooted microshoots, the latter predominantly through in vitro tissue culture. Both techniques are used to achieve rapid multiplication of trees with favorable genetic combinations and to capture a large proportion of the genetic diversity in a single generation cycle. However, adventitious rooting of shoots (cuttings) is often not efficient due to various problems, such as scarcity of roots and cessation of their growth, both of which limit the application of vegetative propagation in some conifer species. Many factors are involved in the adventitious rooting of shoots, including physical and chemical ones, such as plant growth regulators, carbohydrates, light quality, temperature and rooting substrates, or media [reviewed by Ragonezi et al. (Trees 24(6):975–992, 2010)]. The focus of this review is on biological factors, such as inoculations with Agrobacterium rhizogenes, plant-growth promoting rhizobacteria and other endophytes, and mycorrhizal fungi, which were found to stimulate adventitious rooting. These microorganisms could contribute not only to adventitious root development but also to help in protecting conifer plants against pathogenic microorganisms, facilitate acclimation and transplanting, and contribute to more sustainable, chemical-free forests.     

植物生长调节剂对鹿角杜鹃扦插繁殖的影响

以腐殖土为基质,研究了5种植物生长调节剂的4个浓度处理、以及萘乙酸(NAA)不同浓度与浸泡时间处理对鹿角杜鹃(Rhododendron latoucheae)当年生枝条扦插繁殖12个育苗指标的影响及各指标间的相关性,并运用隶属函数法对各处理组合的育苗效果进行了综合评价。结果表明:5种生长调节剂中,赤霉素(GA3)、吲哚丁酸(IBA)处理在大部分育苗指标上表现良好,为鹿角杜鹃扦插育苗的理想调节剂,吲哚乙酸(IAA)效果次之,6-苄氨基嘌呤(6-BA)、NAA处理的育苗指标表现较差;4个浓度水平上,愈伤率、腐烂率及老叶留存率总体以低浓度处理最佳,随着浓度升高效果下降;其它9个指标对浓度的响应因生长调节剂种类而异。各指标相关性分析发现,4个根系生长指标,即不定根数、最长不定根长、总根数及根系直径之间呈极显著正相关,但它们与愈伤率、腐烂率、生根率及老叶留存率、新梢率间的相关性较弱。隶属函数综合评价表明,50 mg/L GA3处理为鹿角杜鹃扦插育苗的最佳组合,其次为100 mg/L GA3和400 mg/L IBA处理。本研究为杜鹃花产业化育苗提供了科学依据。     

绿巨人白掌不同外植体组织培养研究

本文研究白鹤芋属观赏品种绿巨人白掌的茎顶、叶片、叶柄和幼花序的组织培养和快速繁殖技术。茎顶培养以0.2mg／LNAA 3．0mg／L6-BA培养效果较好;叶片诱导适宜的培养基为0．5mg／LNAA 5．0mg／L6-BA,分化培养基为0．2mg／LNAA 3．0mg／L6-BA;叶柄以0．5mg／L2,4-D 3．0mg／L6-BA诱导效果最好,分化适宜培养基为0．5mg／LNAA 3．0mg／L6-BA;幼花序胚状体的诱导则以0．5mg／L2,4-D 5．0mg／L6-BA效果最好,成苗培养基为0.5mg／LNAA 3．0mg／L6-BA;255mg／L的KH2P04比较／比较适合于绿巨人白掌丛芽的增殖;生根培养基以1／2MS 0.50mg／LNAA较适宜。     

千层金嫩枝扦插繁殖技术

本研究用L_(16)(4~5)正交试验方法,研究了基质、穗条长度、植物生长调节剂及其浓度对千层金嫩枝扦插生根率的影响.结果表明,基质和生长调节物质对生根率有极显著的影响,而植物生长调节剂浓度与穗条长度对生根率有显著的影响,4个因素对干层金嫩枝大田扦插生根率影响从大到小分别是基质、生长调节物质、植物生长调节剂浓度和穗条长度.用浓度100 mg/L的NAA浸泡9 cm插穗2 h,在混和基质上扦插,平均生根率可达92%,且生根及新梢抽出时间早,侧根数量多,扦插效果最好.     

3种植物生长调节剂对树头菜扦插生根的影响

利用植物生长调节剂不同种类及质量浓度处理树头菜插穗,了解其扦插生根机制并筛选出适宜扦插繁殖的生长调节剂及浓度配比,为其扩大繁殖和生产提供科学依据。以树头菜一年生枝条为材料,采用3种植物生长调节剂（IAA、NAA、ABT-1）的3种不同质量浓度进行正交试验,清水处理（CK）作为对照,扦插3个月后对其芽生长量及生根性状（生根率、生根量、最长根长、平均根长等）进行测定并综合分析。本次试验筛选出的树头菜扦插最优方案为A1B2C2,即ABT-1质量浓度为50 mg·L^-1、NAA质量浓度为200 mg·L^-1、IAA质量浓度为200 mg·L^-1,该处理生根率（83.33%）、平均根长（24.03 mm）、最长根长（46.13 mm）、平均根数（24条）、根系效果指数（19.06）为CK的2.27、2.97、3.03、4.50、12.79倍,根系发育较好。不同植物生长调节剂在适宜的浓度下混合利用可以显著增加树头菜的生根能力,进而加快生长并提高其扦插生根率。     

Conservation strategies for threatened medicinal plant – Barleria prionitis L. – using in vitro and ex vitro propagation techniques

Over-utilisation and continuous depletion of medicinal plants have affected their supply and loss of genetic diversity. Hence the current study is based on conservation strategies for threatened medicinal plants with special reference to Barleria prionitis L. using in vitro and ex vitro propagation techniques. We have developed here a protocol for plant regeneration of Barleria prionitis L. We have also developed an efficient system of vegetative propagation of Barleria prionitis L. through stem cuttings using revive rooting hormones. These studies can be useful for conservation strategies of this important medicinal plant.     

The effect of shading of stock plants on rhizogenesis in stem cuttings of Berberis thunbergii ‘Red Rocket’

In order to improve vegetative propagation of Berberis thunbergii ‘Red Rocket’, stock plants were subjected to shading and IBA treatment, as well as to the application of two commercially available rooting powders. Spraying stock plants with IBA 24 hours prior to cutting harvest gave the effect comparable to the use of rooting powders. Reduction of light intensity by 50% and 96% of ambient prior to harvest of cuttings improved rooting. Positive effect of shading results in changes in shoot anatomy, i.e. a weaker sclerenchyma development. Enhanced rooting in cuttings from shoots grown under reduced light intensity was accompanied by a decrease in the concentration of soluble proteins and by an increase in total chlorophyll content while the concentration of total soluble sugars remained unaffected.