Indole-3-butyric Acid Treatment Research Articles

Transcriptome profiling of indole-3-butyric acid–induced adventitious root formation in softwood cuttings of walnut

Inducing adventitious root (AR) formation in mature walnut species (Juglans L.) is challenging. However, the AR formation of mature trees can be improved by rejuvenation. In rejuvenated cuttings, exogenous indole-3-butyric acid (IBA) is essential for AR formation, and the underlying mechanism is still not well understood. Therefore, we utilized transcriptome sequencing to investigate the mechanism of IBA-induced AR formation. Our results revealed that, in comparison to the control group, IBA treatment (9 mM) significantly increased the endogenous indole-3-acetic acid (IAA) content, leading to an enhanced rooting rate. We performed RNA sequencing to identify differentially expressed genes (DEGs) between the IBA-treated and control (CK) groups at 1, 2, 3, and 5 days after cutting (DAC). The results showed that, compared to the control cuttings, there were 1 539, 889, 785, and 984 up-regulated genes and 2 791, 2 936, 3 017, and 1 752 down-regulated genes, at 1, 2, 3, and 5 DAC, respectively. Analysis of RNA-seq data revealed that G-type ATP-binding cassette 36/37 (ABCG36/37) and ATP-binding cassette subfamily D 1 (ABCD1), associated with IBA transport, were down-regulated in the rejuvenation cuttings. In contrast, PIN-FORMED (PIN) and PINOID (PID), associated with auxin efflux, were up-regulated. We identified 49 auxin/indole-3-acetic acid (AUX/IAA)-encoding genes, including IAA1, IAA3, IAA5, IAA6, IAA8, IAA11, IAA12, IAA19, and IAA20, which were up-regulated at 1–5 DAC in the rejuvenated cuttings. This study highlights that the overexpression of JrWOX5/11 in poplar significantly enhance AR growth, as evidenced by increased root length, surface area, volume, and quantity. Moreover, the co-expression network analysis involving JrWOX11 and JrWOX5 in walnut cuttings elucidates complex genetic interactions, underscoring their pivotal role in the formation of AR. Our data supported the following molecular mechanism of IBA-induced adventitious root formation. Firstly, IBA is converted to free IAA in peroxisomes. Then, the highly concentrated IAA in the procambium and parenchyma cells induces WUSCHEL-related homeobox 11 (WOX11) expression at 2 days. Finally, WOX11 acts redundantly to up-regulate WOX5, initiating the development of root primordia cells.

Own-rooted Walnut Propagule of Four Walnut (Juglans) Rootstocks and Main Cultivated Cultivar Liaoning 1 Acquirement through Layering under Field Conditions

Walnut, a woody plant, is regarded as having difficulty rooting when propagated by vegetative methods, such as cutting and layering. A layering experiment was conducted in 2018 and 2022. In 2018, some Juglans species, including J. regia L. seedling (JR), J. regia cv. Liaoning 1 (JR LN1), J. hopeinesis Hu seedling (JH), J. mandshurica Maxim seedling (JM), and J. nigra L. seedling (JN), were the mother plants. The specific research hypotheses were that own-rooted walnut propagule could be obtained through layering. the rooting capacity of different Juglans species would be different, and the rooting ability of JN would be the highest among the samplings. The results indicated that all of these species in the experiment could be rooted by etiolation and indole-3-butyric acid (IBA) treatment and that root occurrence was found 6 to 7 weeks after IBA treatment. The layers (shoots from the mother plant) on the seedlings of JR, JH, and JM obtained rooting percentages (RP) of 75.55%, 84.45%, and 86.67%, respectively, and root numbers (RNs) of 21.8, 42.8, and 38.8, respectively, after 20 days of etiolation and 1% IBA treatment. JR LN1 had difficulty rooting in equal conditions and had a RP of 31.11%. In 2022, JR LN1 was the only mother plant and the IBA concentration was increased to obtain satisfactory RP and RN. With the 4% and 8% IBA treatments, RPs of 88.9% and 93.3% and RNs of 40.3 and 27.7, respectively, were achieved. During the experiment, the RP, RN, root length (RL), and root diameter (RD), as well as the layer height (LH) and layer diameter (LD), were investigated and evaluated. Layers with low vigor were more likely to root, as shown by a nonparametric test conducted for the height and diameter of the layers of the rooting and nonrooting groups. A significantly negative correlation (r = −0.548) was observed between RN and LH. Moreover, the quality of the best results of JR LN1 layering propagule and that with ‘liaoning 1’ 1-year-old seedling were compared. Our results provide more support for the possibility of vegetative propagation of walnut by layering and more information regarding the clonal cultivation of walnut trees and the own-rooted seedling establishment of walnut cultivars.

Enhancing the Propagation and Cultivation Framework of Greek Rosa canina L. Germplasm via Sustainable Management Techniques

The current study aimed to enhance the sustainable utilization framework of the underutilized Greek native Rosa canina L. (rosehip) germplasm as a potential novel crop that can deliver high-quality products with minimum environmental impact. The first part of the work includes asexual propagation trials on cuttings of two Greek R. canina genotypes, assessing the potential of various alternative rooting enhancers to the conventionally used indole-3-butyric acid (IBA), as affected by rooting substrate and cutting type. The propagation results showed commercially acceptable (>50%) rooting rates for 2500 ppm IBA, coconut water, rooting gel and aloe vera treatments and similar rooting attributes of root number and length, providing evidence for the feasibility of using alternative rooting enhancers. The second part of the work presents the results of an ongoing ex situ cultivation trial assessing the potential of a diversified organic fertilization regime against conventional fertilization on fruit size and yield, coupled with macro- and micro-nutrient concentration, in the leaves of four Greek R. canina genotypes. The results showed a genotype-specific response in rosehip fruit size and yield to fertilization, with the organic regime showing comparable results to the conventional fertilization. In addition, diverse patterns, depending on the element, of macro- and micro-nutrient content were measured in the leaves in both fertilization regimes, which were, however, genotype-dependent. Overall, the current study reports for the first time the potential of alternative rooting enhancers for commercial R. canina propagation coupled with the application of organic fertilization as a means of establishing a diversified cultivation protocol for underutilized R. canina germplasm. The current results can be employed to further facilitate a value chain creation for Greek rosehips as a raw material for use in the agro-alimentary and medicinal–cosmetic sectors.

Optimization of Rooting Behaviour by the Application of IBA on the Cuttings of Queens Flower (Lagerstroemia speciosa)

Background: Queen’s flower (Lagerstroemia speciosa) is an important ornamental plant that is utilised in residential landscape and avenue plantation for both public and private purposes around the world. Seed dormancy problem in Lagerstroemia which negatively affects germination. To overcome the challenges associated with seed propagation, researchers have explored rooted Lagerstroemia speciosa cuttings as an alternative method. Methods: Three concentrations of IBA (Indole-3- butyric acid) @ 1000 ppm, 2000 ppm and 3000 ppm were used to root initiation of Lagerstroemia speciosa stem cuttings. There were four treatments: 1000 ppm, 2000 ppm, 3000 ppm and control. Result: The 2000 ppm IBA treatment performed the better response in comparision to other treatments and recorded, 79 per cent rooting, followed by the treatment 3000 ppm IBA, (76 per cent rooting) and in the control, (68 per cent). In 2000 ppm IBA, the percentage of rooting, the number of roots per cutting and the length of the longest roots all are at their peak as well as showed the superior growth performance. The growth parameters of IBA-@ 2000 ppm treated cuttings revealed that this is the optimum IBA concentration for Lagerstroemia speciosa propagation trough cuttings in a semi-arid climate.

Assessment of the Responses of Chickpea (Cicer arietinum L.) to the Exogenous Application of Gibberellic Acid and Indole Butyric Acid at Different Crop Development Stages

Background: Chickpea (Cicer arietinum L.) is one of the most important pulse crops in the world. In Tunisia, the chickpea is vulnerable to fluctuation in production in the last few decades. However, phytohormones are known to play crucial roles in regulating different development processes in plants. Methods: This research was conducted in Petri dish and pot experiments in order to determine the effect of gibberellic acid (GA3) and indole butyric acid (IBA) phytohormones on some growth parameters of chickpea. In this study, GA3 at concentrations of 0, 0.05, 0.1, 0.15 and 0.2 g/l and IBA at concentrations of 0, 10-5, 10-4, 10-3 and 10-2 g/l were applied at different stages of chickpea development. Result: Results of Petri dishes trial revealed that IBA (10-4g/l) and GA3 (0.2 g/l) hormones improved significantly the shoot and root length of chickpea plant. Results of pots pointed out that the chickpea achieves the highest plant height when IBA (10-4 or 10-3 g/l) and GA3 (0.2 g/l) were used at pre-flowering stage. The IBA and GA3 application with concentrations of 10-3 g/l and 0.1 g/l, respectively allowed the highest nodule number at post-flowering stage. The parameters number of branches, fresh and dry weight of the aerial part and leaves number were improved in chickpea plants treated with IBA and GA3 at pre-flowering and post-flowering, respectively. Similarly, the number of flowers was promoted by the two hormones. The weight and the number of seeds were significantly enhanced by all IBA treatments in plants. An increase in weight and the number of seeds was observed at post-flowering phase of GA3 treatment. Thus, these results identified the beneficial effect of tested phytohormones in chickpea growth.

Micropropagation of autochthonous olive varieties from Türkiye

Olive (Olea europaea L.) is one of the oldest cultivated fruit species in the world. Fruits and oils of autocthonous olive varieties (native Turkish olive varieties) with unique sensory properties (taste, smell and aroma) gain importance recently. Particularly olive oil companies looking for varieties that have distinct taste, smell and aroma in their oil. Propagation of olive varieties by cuttings and grafting is very difficult and expensive, therefore it is important to find solution for easy and mass propagation. Micropropagation is particularly beneficial to propagate plants that are difficult to reproduce conventionally or to ensure virus-free plants or plants with particular qualities. In this study, in vitro micropropagation success of two autocthonous olive varieties (‘Mavi’ and ‘Guleki’) grown in the origin center of olive, Southeast Anatolia, Türkiye was investigated. Both varieties, have distinct smell, taste and aroma and are difficult to root by cuttings. The effects of three different medium OM (Olive Medium), WPM (Woody Plant Medium) and DKW (Driver-Kuniyuki Walnut Medium) and two different growth regulators BAP (6-Benzylaminopurine) and Zeatin on shoot induction (proliferation) in the in vitro micropropagation of the olive varieties were examined. Obtained shoots were later subjected to in vitro rooting and acclimatization. The highest proliferation efficiency and shoot length for both varieties were obtained with the use of 1 mg Zeatin+0.1 mg GAɜ hormone combinations on OM medium. ‘Mavi’ variety formed more roots compared to ‘Guleki’ (3.33 vs. 2.75 per shoots), and gave the highest rooting rate of 74.33% with 2 mg IBA (Indole Butyric Acid) treatment on ½ OM medium. In terms of rooting rate, Guleki gave the highest rooting (100%) on medium containing ½ OM, 0.2 mg GA3 and 4 mg IBA. 60% and 75% of the micropropagated plants of ‘Mavi’ and ‘Guleki’ varieties adapted well to the external conditions.

Plant-Derived Smoke Mitigates the Inhibitory Effects of the Auxin Inhibitor 2,3,5-Triiodo Benzoic Acid (TIBA) by Enhancing Root Architecture and Biochemical Parameters in Maize.

The present study was designed to investigate and compare the effects of plant-derived smoke (PDS) and auxin (IAA and IBA) on maize growth under the application of 2,3,5-triiodo benzoic acid (TIBA). For this purpose, indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA), each at a concentration of 10 ppm, along with PDS at a ratio of 1:500 (v/v) were used alone and in combination with 10 ppm of TIBA. The results indicate that the germination percentage (%) of maize seeds was enhanced under IAA, IBA and PDS treatment. However, IAA and IBA resulted in reduced germination when applied in combination with TIBA. Importantly, the germination percentage (%) was improved by PDS under TIBA treatment. The analysis of seedling height, length of leaves, and number of primary, seminal and secondary/lateral roots showed improvement under individual treatments of IAA and IBA, PDS and PDS + TIBA treatment, while these values were reduced under IAA + TIBA and IBA + TIBA application. Chlorophyll content, total soluble sugars and antioxidative enzymatic activity including POD and SOD increased in seedlings treated with PDS alone or both PDS and TIBA, while in seedlings treated with IAA and TIBA or IBA and TIBA, their levels were decreased. APX and CAT responded in the opposite way-under IAA, IBA and PDS treatment, their levels were found to be lower than the control (simple water treatment), while TIBA treatment with either IAA, IBA or PDS enhanced their levels as compared to the control. These results reveal that PDS has the potential to alleviate the inhibitory effects of TIBA. This study highlights the role of PDS in preventing TIBA from blocking the auxin entry sites.

Alternative Rooting Methods for Medicinal Cannabis Cultivation in Denmark-Preliminary Results.

Cannabis sativa L. is typically propagated through micropropagation or vegetative cuttings, but the use of root-inducing hormones, such as indole-3-butyric acid (IBA), is not allowed for growing medicinal cannabis in Denmark. This study examined alternative rooting treatments, including Rhizobium rhizogenes inoculation, water-only as well as IBA treatments, in eight cannabis cultivars. PCR on root tissue suggested that 19% of R. rhizogenes-inoculated cuttings were transformed. These were derived from "Herijuana", "Wild Thailand", "Motherlode Kush", and "Bruce Banner", indicating a variation in cultivar susceptibility toward R. rhizogenes. A 100% rooting success was achieved regardless of cultivar and treatment, suggesting that alternative rooting agents are not required for efficient vegetative propagation. However, rooted cuttings differed in shoot morphology with improved shoot growth in cuttings treated with R. rhizogenes (195 ± 7 mm) or water (185 ± 7 mm) while inhibited shoot growth under IBA treatment (123 ± 6 mm). This could have advantageous economic implications should cuttings not treated with hormone reach maturity faster than those exposed to the hormone, thereby contributing to completing a full growing cycle more effectively. IBA exposure increased root length, root dry weight, and root/shoot dry weight ratio compared to cuttings treated with R. rhizogenes or water but simultaneously inhibited shoot growth compared to these.

Regulatory Mechanisms of ArAux/IAA13 and ArAux/IAA16 in the Rooting Process of Acer rubrum.

Acer rubrum is difficult to root during cutting propagation. Auxin/indole-acetic acids (Aux/IAA) proteins, which are encoded by the early response genes of auxin, are transcriptional repressors that play important roles in auxin-mediated root growth and development. In this study, ArAux/IAA13 and ArAux/IAA16, which were significantly differentially expressed after 300 mg/L indole butyric acid treatment, were cloned. Heatmap analysis revealed that they might be associated with the process of adventitious root (AR) growth and development mediated by auxin. Subcellular localization analysis showed that they performed their function in the nucleus. Bimolecular fluorescence complementation assays revealed the interactions between them and two auxin response factor (ARF) proteins, ArARF10 and ArARF18, confirming their relevance to AR growth and development. Overexpression of transgenic plants confirmed that the overexpression of ArAux/IAA13 and ArAux/IAA16 inhibited AR development. These results help elucidate the mechanisms of auxin-mediated AR growth and development during the propagation of A. rubrum and provide a molecular basis for the rooting of cuttings.

Light Reduction, Banding, and IBA Treatments Influence Adventitious Rooting of Lindera benzoin Stem Cuttings

An investigation was undertaken to determine whether various light reduction and shoot banding treatments could increase rooting on stem cuttings of Lindera benzoin [(L.) Blume] (northern spicebush), a difficult-to-root woody plant. Stock plants were grown under one of three light conditions (light, shade, or etiolation). Emerging shoots received either no treatment or a banding treatment that involved adhering a hook-and-loop fastener coated with varying concentrations of indole-3-butyric acid (IBA) around the shoot base to create a localized etiolated zone before taking cuttings. Data on rooting percentage and number of roots per cutting were analyzed using logistic and Quasi-Poisson regression, respectively. Etiolated cuttings treated with a band without IBA had the highest rooting probability and number of roots; however, etiolated cuttings across all banding treatments had similarly successful results. Additionally, there were several significant differences in rooting probabilities and root numbers between banding treatments within the shade- and light-grown groups. This research evaluated asexual propagation approaches for use with northern spicebush and provides a framework for the adoption and development of this taxon as a nursery crop.

Growth regulators on the shooting and rooting of Tamarix chinensis stem cuttings

Tamarisk (Tamarix chinensis) is a halophyte that plays a critically important role in the restoration of saline land. It reproduces via seeds, but the germination rate of seeds is low in its natural environment, which greatly limits its ability to spread. Vegetative propagation is a useful method for enhancing the quality and reproduction of plants, and the effects of growth regulators on stem cuttings vary. Here, we evaluated the effects of different concentrations (0, 100, 250, 500, 1,000, 1,500, 2,000, and 3000 mg L−1) of gibberellin A3 (GA), indole-3-butyric acid (IBA), naphthaleneacetic acid (NAA), and 6-benzylamine purine (BAP) on the survival, shoots, and root formation of tamarisk stem cuttings. The survival of tamarisk stem cuttings was 100% in the 100 mg L−1 GA, 1000 mg L−1 IBA, and 500 mg L−1 BAP treatments. The highest number of new shoots per cutting was observed in the 1000 mg L−1 IBA treatment and three times higher than in the control (0 mg L−1; CK), only significant difference with the 250 mg L−1 NAA treatment. The fresh weight of the shoots and roots was higher in the 100 mg L−1 GA, 1000 mg L−1 IBA, 500 mg L−1 BAP, and 250 mg L−1 NAA treatments, and was 161%, 200%, 114%, 66% and 150%, 300%, 150%, 183% higher than in the CK, respectively. Although, the fresh weight of the shoots and roots was highest in the 1000 mg L−1 IBA treatment, it is only significantly differed from that in the 500 mg L−1 BAP and 250 mg L−1 NAA treatments in the fresh weight of the shoots. No significant differences in root length and diameter were observed in the 100 mg L−1 GA, 1000 mg L−1 IBA, 500 mg L−1 BAP, and 250 mg L−1 NAA treatments. Root surface area and volume were significantly higher in the 250 mg L−1 NAA treatment than in the 1000 mg L−1 IBA and 500 mg L−1 BAP treatments. Overall, growth regulators significantly affected the shooting and rooting ability of tamarisk stem cuttings. The following treatments were the most effective for enhancing the quality of tamarisk stem cuttings: 100 mg L−1 GA, 1000 mg L−1 IBA, 500 mg L−1 BAP, and 250 mg L−1 NAA. The growth of tamarisk stem cuttings was maximized in the 1000 mg L−1 IBA treatment, and the survival of tamarisk stem cuttings was lowest in the 250 mg L−1 NAA treatment. This study provides a theoretical basis and data support for the technology of growth regulators on the shooting and rooting of tamarisk stem cuttings.

Micropropagation of Hemp (Cannabis sativa L.)

Hemp (Cannabis sativa L.) is commonly grown for the medicinal secondary metabolites produced by pistillate inflorescences. Micropropagation is a valuable method of propagating hemp plants because of the aseptic process and the production of true-to-type propagules. The hemp cultivar TJ’s CBD was used for a series of experiments to compare media inputs and practices for the clonal micropropagation of hemp. For stage I, shoot tips harvested from stock plants that were grown in a growth chamber produced less endogenous contamination in newly established cultures than shoot tips harvested from the greenhouse. In addition, stage I disinfection treatments with 20%, 40%, and 60% bleach (7.5% sodium hypochlorite) for 10 minutes had no differences in surface contamination rates. All concentrations were able to clean explants equally, and no damage to the explants was observed. For stage II, there were no differences in growth and multiplication rate between shoot tip or nodal explants. In addition, no differences were observed between the gelling agent’s agar, agargellan, and gellan gum at standard rates. When basal nutrient formulations were compared at standard rates and with their respective vitamins, Murashige and Skoog, Linsmaier & Skoog, and Driver & Kuniyuki Walnut media were found to be superior to Lloyd & McCown Woody Plant Medium. Media pH levels of 4.0, 5.0, 5.8, 6.0, and 7.0 were compared, and no differences were observed in final fresh weights, shoot lengths, or quality ratings. The pH levels of 5.8, 6.0, and 7.0 generated a greater number of lateral nodes. Sucrose levels of 0%, 1.5%, 3.0%, 4.5%, and 6.0% (wt/vol) were also compared, with the 1.5% and 3.0% rates showing greater fresh weights, shoot lengths, and quality ratings. Growth room temperatures of 22, 24, 26, and 28 °C were compared, with temperatures of 28 and 26 °C generating greater fresh weights, shoot lengths, numbers of nodes, and quality ratings compared with cooler temperatures. The cytokinins 6-enzylaminopurine (BA), 6-(γ,γ-dimethylallylamino) purine (2iP), and thidiazuron (TDZ) were compared at 1.0, 5.0, and 10.0 μM concentrations. The 5.0-μM TDZ treatment generated greater fresh weights and numbers of lateral nodes; however, it also produced the shortest shoot lengths and lowest quality ratings. The 2iP treatments at 1.0 and 5.0 μM, and the BA treatment at 1.0 μM produced the greatest quality ratings. The 5.0-μM 2iP level was considered the best treatment for stage II multiplication based on high ratings, in addition to the greater final fresh weights, shoot lengths, and numbers of nodes that were produced. For stage III experiments, the auxins indole 3-butyric acid (IBA) and 1-naphthylacetic acid (NAA) were compared at concentrations of 0.25, 0.5, and 2.5 μM. Auxin treatments of 0.25 μM NAA, 0.5 μM NAA, and 2.5 μM IBA generated the greatest final shoot fresh weights, root fresh weights, and numbers of nodes. However, the 2.5-μM IBA treatment resulted in a higher overall rating. For stage IV, ex vitro rooting and acclimation trials compared a dome and an intermittent mist system, as well as treated the unrooted cuttings with an externally applied auxin. Acclimating with a dome produced greater shoot heights, fresh shoot weights, and overall ratings compared with the mist system. The auxin treatment mildly increased fresh root weight, but was not as important to acclimation success as the domed environment. It has been concluded that a micropropagation system that uses lower rates of sucrose, higher growing temperatures, and lower rates of the cytokinins BA and 2iP are optimal for the micropropagation of hemp. In addition, when acclimating hemp plants from tissue culture, an in vitro stage III can be bypassed and plants can be rooted ex vitro during stage IV acclimation with a dome with or without additional auxin treatments.

Different Responses to Adventitious Rhizogenesis under Indole-3-Butyric Acid and Seaweed Extracts in Ornamental’s Cuttings: First Results in Photinia x fraseri ‘Red Robin’

Fraser’s photinia ‘Red Robin’ (Photinia x fraseri Dress, Rosaceae family) is an important primary ornamental landscaping species with optimal hedge or screen effects and low maintenance, but it is difficult to root when propagated by cuttings, although high concentrations of phytohormones are used to optimize rhizogenesis. To our knowledge, there is currently no feasible enhanced method for photinia vegetative propagation through stem cuttings, using seaweed extract-based biostimulants as root promoters. Given the economic importance of the species, this research aims to assess the effects of indole-3-butyric acid (IBA) and seaweed extract-based stimulators on the quality of photinia ‘Red Robin’ cuttings, in terms of rooting indicators and ground and aboveground agronomic features. The treatments applied were different concentrations of commercial rooting stimulators compared to an untreated control: C0: distilled water; Rhizopon AA: 1% IBA (R1); Kelpak®: 2 mL L−1 (K2); Kelpak®: 3 mL L−1 (K3); Goteo®: 2 mL L−1 (G2); Goteo®: 3 mL L−1 (G3). The first results showed different responses to adventitious rhizogenesis under IBA and both seaweed extract treatments. At 70 DAC (days after cutting), the seaweed extract stimulated the production of over 80% of cuttings with callus; at 240 DAC, the percentage of rooted cuttings treated under R1 was the highest = 34.3%; the worst results were obtained by both biostimulant treatments at the highest doses: K3 = 21.3% and G3 = 20.7%. Furthermore, R1 produced 3.07 roots per cutting, which was 50% higher than the average of all other treatments. The applications of Kelpak® and Goteo® biostimulants, at both concentrations, resulted in an inhibition of root length with values below the untreated control. Rooted cuttings under R1 showed the highest ground (0.35 g) and aboveground (0.47) dry value. Neither seaweed extract, Kelpak® or Goteo®, at different concentrations, improved both the ground and above-ground weights of rooted cutting, compared to the untreated control, indicating that these natural products are not suitable for Fraser’s photinia ‘Red Robin’ propagation using this methodology. The overall quality of cuttings in IBA treatment was the strongest, with 1%, being the optimum concentration. Further research must be conducted to propose effective agronomic protocols by investigating application methods, doses and number of applications, and to clarify the biochemical and molecular mechanisms of action of these seaweed extracts.

Vegetative propagation of Xylopia parviflora, a wild medicinal spice tree species in the tropics: insights for domestication

Objective: Xylopia parviflora (A. Rich.) Benth. (commonly known as “striped African pepper”) is one of the most socio-economically high-valued tree species of the Central and Western African humid forests. Its propagation is hindered by poor seed germination. The present study aimed at examining its potential for vegetative propagation through the rooting of stem cuttings. Methodology and Results: In a split-plot experimental design, three leaf areas (0, 15 and 30 cm2) and six concentrations [(0, 0.25, 0.5, 1, 2 and 4% (w/w)] of indole-3-butyric acid (IBA) were tested for their effects on stem cutting parameters after five months in a non-mist propagator. Maximum rooting percentage (100%) was recorded with 15 cm2 x 4% IBA, 30 cm2 x 2% IBA and 30 cm2 x 4% IBA treatment combinations. The highest mean root count (9.1) was recorded with 30 cm2 x 4% IBA. The mortality rate of cutting was significantly affected by leaf area only. Leafless cuttings (0 cm2) resulted in 73.5% mortality, which was higher than 11.8% and 10.7% recorded with cuttings having 15 and 30 cm2 leaf areas respectively. Conclusion and application of findings: X. parviflora is amenable to vegetative propagation through rooting of leafy stem cutting within five months. For an efficient propagation of X. parviflora through stem cuttings, the use of cuttings with 30 cm2 leaf area and application of 4% (w/w) IBA are recommended. This is valuable insight into the domestication and in situ conservation of this species that is of direct relevance to the well-being of millions of people in sub-Saharan Africa. Propagation of X. parviflora using robust and low-cost procedure as described in this study would stand as an alternative to the sexual propagation which is hindered by poor seed germination. Keywords: auxin, leaf area, rooting, stem cuttings, striped African pepper.

IBA Delivery Technique and Media Salts Affected In Vitro Rooting and Acclimatization of Eight Prunus Genotypes

Difficult-to-root plants often perform poorly during acclimatization and in vitro rooting can increase the survival and quality of plants. The influence of auxin application and mineral nutrition on in vitro rooting and subsequent effects on plant quality in eight Prunus genotypes were investigated. Microshoots were rooted in vitro on Murashige and Skoog (MS), ½ MS, Driver and Kuniyuki (DKW), or New Prunus Medium (NPM) media formulations in combination with 15 µM indole-3-butyric acid (IBA), 4-day 15 µM IBA pulse, 1 mM 30 s quick-dip, or IBA-free treatments. Shoots were observed pre- and post-acclimatization to determine rooting methods to maximize quality and minimize labor. A genotype-specific response to auxin application was observed with seven of eight genotypes achieving 100% survival when paired with the recommended IBA treatment. Peaches performed best when treated with 4-day IBA pulse or 30 s quick-dip. Rooting of P. cerasifera, it's hybrid to P. persica, and P. munsoniana all benefitted from IBA application. Shoots rooted with 15 µM IBA were smaller and lower quality in most genotypes. DKW maximized size and quality in six genotypes. Better shoots and larger root systems during in vitro rooting produced better plants in the greenhouse with no detrimental effect of callus growth. Rooting techniques to maximize plant quality while reducing labor are specified.

EFFECT OF AUXINS ON PROPAGATION OF HONEY CROP: STEVIA REBAUDIANA (BERTONI) BERTONI.

The present study was conducted to optimize the green house conditions for Propagation of Stevia rebaudiana cuttings. Stevia rebaudiana belonging to the family Asteraceae, is a native to the Brazil and Paraguay. Its leaves produced stevioside, an a caloric natural sweetener. The sweetness of stevioside was 150 -300 times greater than sucrose. Seeds of Stevia were very small in size. Production of Stevia through seeds was not beneficial because seeds were not viable for germination due to their infertility. In present study different concentrations of Naphthalene acetic acid (NAA) and Indole Butyric acid (IBA) were used to study their effect on the rooting of Stevia rebaudiana cuttings. Results showed that highest number of roots per cutting were observed to be 34.9 from 3% NAA solution, showing maximum root length, root number, shoot length and number of nodes per cutting. Cuttings of Stevia rebaudiana responded well in NAA treatment as compared to the IBA treatment. It was concluded that Naphthalene acetic acid was a better choice for enhanced rooting and vegetative propagation of Stevia rebaudiana through stem cuttings.

Vegetative Multiplication Of Psidium Guajava L. Through Stem Cutting

The experiment demonstrated the scope of vegetative multiplication of Psidium guajava L. through stem cutting accrued from three year age plants. Cuttings have been treated with five concentration of auxins viz., control (0%), 0.2%, 0.4%, 0.6% and 0.8% of IBA (Indole-3-butyric acid) solution and rooted within the shade house. Rooted cuttings have been allowed to grow inside the black polybags with 3:1 ratio of soil and farm yard manure respectively for four months to see the surviving capability and initial rooting performance. The experiment showed that the mature stem cutting may be used to propagate the species. The highest root development (80.67%) was recorded within the cuttings treated with 0.6% IBA followed by using 0.8% IBA solution and the lowest in controlled treatment. The highest number root (36.6) was observed in the cuttings treated with 0.8% IBA solution followed by 0.6% IBA and the lowest in the cuttings without IBA treatment (controlled). The maximum survival percentage (74.33%) was recorded in the cuttings treated with 0.6% IBA solution and the minimum (32.33%) was recorded in the control treatment. There was considerable variation in rooting as well as growth of cuttings due to IBA treatment.

Sexual and asexual propagation of Syzygium maire, a critically endangered Myrtaceae species of New Zealand

ABSTRACT Syzygium maire (swamp maire) is an endemic New Zealand Myrtaceae tree species. Current threats to this species include habitat destruction, myrtle rust, declining remnant populations and low capacity for natural regeneration. Large-scale replanting for conservation/restoration initiatives would mitigate against these threats. However, there is limited information available on propagation of this species. In this study, we looked at sexual propagation using seed germination and asexual propagation using softwood cuttings. For seed germination, we examined the effect of seed pretreatments (intact fruit or de-pulped seed) and temperature settings (15/25°C or 20/30°C) to optimise germination. For softwood cutting propagation, we investigated the diameter of the cuttings (1–2 mm or 3–5 mm) and application of exogenous indole-3-butyric acid (IBA) (0, 1.5, 3.0, or 4.5 g L−1) on their efficacy of producing adventitious rooting. The most critical factor for seed germination was the removal of seed pulp. De-pulping the seeds shortened the mean time to germination and positively affected the germination percentage, regardless of the incubation temperature. Germination percentage of ≥94.5% was achieved in seeds sown without pulp. Propagation by softwood cutting of 1–2 mm in diameter was possible without IBA treatment (63.3% of cuttings rooted), but the application of 1.5 g L−1 IBA increased the rooting percentage (to 75%), thereby inducing the production of a higher number of roots. Seed germination and softwood cutting were effective strategies to propagate S. maire. The findings of this research contribute to the knowledge of propagation and restoration of S. maire populations.

Effect of Indole-3-Butyric Acid on Growth of V-1 Mulberry Cuttings with Varying Number of Buds in Bangalore

The present study was conducted in Bangalore. It aims at studying the effect of different concentrations of indole-3-butyric acid (IBA) (1000, 2000 and 3000 ppm) on V-1 mulberry cuttings with varying number of buds (one, two, three and four) consist of twelve treatments which were replicated thrice in Factorial CRD. The results on interaction effect of various concentration of IBA on mulberry cuttings with varying number of buds recorded best results in three budded cuttings treated with 3000 ppm of IBA regarding number of sprouted cuttings (14.67) and survival percentage (96.66%) of the saplings. Number of leaves (10.60) and length of shoot (26.63 cm) was maximum in two budded cuttings treated with 3000 ppm of IBA and the results of this interaction were on par with three budded cuttings treated with 3000 ppm of IBA. Whereas, one budded cutting without IBA treatment recorded minimum number of sprouted cuttings (9.67), survival percentage (43.33%), number of leaves (5.67) and length of shoot (21.43 cm). From the present experiment, we can recommend to use two budded cuttings treated with 3000 ppm of IBA instead of three budded cuttings treated with 3000 ppm of IBA.

Influence of light quality and some growth regulators in inducing the production of Podophyllotoxin, a bioactive compound against cancer, in adventitious roots formed in the leaves of Hyptis suaveolens

Podophyllotoxin (PTOX) is an aryltetraline lignan used to treat skin lesions, such as warts, human papilloma virus, and genital infections. Hyptis suaveolens has PTOX in its roots and the culture of its plant tissues in vitro has been increasingly used to produce rare and high-quality medicinal compounds. Adventitious roots are an attractive source of phytochemicals due to their genetic and biosynthetic stability. Thus, the aim of the present study is to investigate adventitious roots’ induction in leaves and nodal segments under different light qualities and auxins in H. suaveolens. Adventitious roots have only emerged in H. suaveolens leaves grown in semi-solid MS medium, in the absence of light and under red light-emitting diode (LED). Root dry weight values recorded for these treatments were statistically equal to each other, i.e., 21.84 and 29.81 mg, respectively. PTOX quantification was performed in the dark (10.72 µg g−1) and under red LED (9.93 µg g−1). Indole-3-butyric acid (IBA) and naphthaleneacetic acid (NAA) (0.5, 1.0 and 2.0 mg L−1) concentrations induced adventitious roots’ formation in leaves of plants belonging to this species. Explant supplemented with 2.0 mg L−1 NAA led to higher root dry weight (45.53 mg) in leaves. However, the 1.0 mg L−1 IBA treatment produced more PTOX (9.96 µg g−1 root). Nodal segments of H. suaveolens, IBA and NAA concentrations (0.5, 1.0 and 2.0 mg L−1) also induced adventitious roots’ formation. The treatment with 0.5 mg L−1 IBA resulted in higher root dry weight (37.62 mg) in the nodal segment. However, 1 and 2 mg L−1 IBA resulted in lower root dry weight and higher PTOX (9.97 µg g−1 and 9.95 µg g−1). In conclusion, adventitious root formation and PTOX induction in H. suaveolens leaves grown in semi-solid MS medium only happen in plants grown in the dark and under monochromatic red LED light. Growth regulator NAA was the best element to induce adventitious roots’ emergence in leaves, whereas IBA was the best one for such a purpose in nodal segment. Growth regulator NAA can inhibit the synthesis of PTOX, but IBA induces this secondary compound.