The present study reports a simple protocol for in vitro regeneration of Aglaonema ‘Valentine’ using axillary shoot explants for rapid multiplication and production of true-to-type plants. Different concentrations of benzyladenine (BA; 0, 1, 3, 5, and 7 mg·L−1), kinetin (Kin; 0, 1, 3, 5, and 7 mg·L−1), thidiazuron (TDZ; 0, 0.5, 1.0, 1.5, and 2.0 mg·L−1), naphthalene acetic acid (NAA; 0, 0.5, and 1.0 mg·L−1), and indole-3-butyric acid (IBA; 0, 0.5, and 1.0 mg·L−1) were used for shoot regeneration. The highest shoot proliferation (5.0) was obtained on Murashige and Skoog (MS) medium supplemented with 1.5 mg·L−1 TDZ and 1 mg·L−1 NAA. In vitro rooting was easily achieved with 100% at all concentrations of NAA and IBA supplemented to half- or full-strength MS medium. Regenerated plantlets were acclimatized in greenhouse with 100% survival rate. Randomly amplified polymorphic DNA (RAPD) analysis confirmed the genetic fidelity of the regenerated plantlets and mother plant.
Grape (Vitis vinifera) waste management is a major problem in juice production, but it could be transformed into a major opportunity if the waste was recycled and used as a nursery growing medium. The aim of this study was to evaluate the suitability of four composts based on squeezed grape fruit waste (SGFW), mixed with coir or vermiculite in a one-to-one ratio by volume to form 13 growing media, for seed germination and seedling growth of ‘Mrs. Burns’ lemon basil (Ocimum basilicum var. citriodora). The final germination percentage (FGP), corrected germination rate index (CGRI), survival percentage, and seedling growth of ‘Mrs. Burns’ lemon basil were the variables measured. Pure SGFW reduced seed germination and seedling growth. The medium combining pure SGFW with vermiculite in a one-to-one ratio by volume was optimal for seed germination and seedling growth; in this medium the highest FGP, CGRI, survival rate, and growth parameters were recorded. The negative effects of pure SGFW composts were eliminated by mixing all composts with coir or vermiculite. These waste recycling media are low-cost products that can be beneficially used in nurseries on a commercial scale.
Breaking of dormancy in african juniper (Juniperus procera) seeds is a challenge faced by nurseries attempting to grow large numbers of this plant for restoration projects. The purpose of this study was to develop a protocol for breaking dormancy and stimulating germination in african juniper. Seeds were presoaked in different concentrations (0, 1, 10, or 20 mg·L−1) of gibberellic acid (GA3), indole-3-butyric acid (IBA), and naphthalene acetic acid (NAA), and incubated under different air temperatures (10, 15, and 20 °C). The petri dishes were monitored daily for 84 days, to record germination percentage, rate, and uniformity, and the growth of shoots and roots, and biomass production. The highest germination percentages were obtained under 20 °C with a high concentration of NAA (20 mg·L−1). The greatest seedling growth was under 20 °C with IBA. The greatest seedling length was under 20 °C with a low concentration of IBA (1 mg·L−1). The greatest shoot fresh weight was under 20 °C with medium GA3 concentration (1 mg·L−1). Compared with the control, almost all growth regulator treatments stimulated higher germination percentages and vigor indices with increased temperatures.
The present study reports on the effect of humic and salicylic acids on the growth, yield, and fruit quality of three red sweet pepper (Capsicum annuum) cultivars: Barbero, Ferrari, and Imperio. The plants were grown in a greenhouse and the leaves were treated with humic or salicylic acids at 0, 0.5, 1.0, and 1.5 g·L−1 at 20, 40, and 60 days after transplanting. Foliar application of humic or salicylic acids significantly increased vegetative growth, fruit yield, and quality of the three cultivars as compared with the control plants. However, salicylic acid treatment proved more effective than humic acid treatment. Red sweet pepper plants of all three cultivars sprayed with 1.5 g·L−1 salicylic acid showed the greatest vegetative growth; fruit yield components, such as fruit number, diameter, and fresh and dry weights; and fruit quality traits, such as vitamin C content, total soluble solid content, titratable acidity, and total sugar content, than the plants in all other treatments. There were significant differences (P ≤ 0.05) among cultivars in response to humic and salicylic acid foliar application; ‘Ferrari’ showed significantly higher yield and productivity than ‘Barbero’ or ‘Imperio’. ‘Ferrari’ plants sprayed with 1.5 g·L−1 salicylic acid showed the highest fruit weight (202.41 g) and flesh thickness (68 mm), both of which are preferred by consumers, and therefore, have increased market value. This treatment also increased total yield by 27.7% (16.03 t·ha−1), 15.9% (12.38 t·ha−1), and 17.9% (11.88 t·ha−1) in ‘Barbero’, ‘Ferrari’, and ‘Imperio’, respectively. Therefore, salicylic acid foliar application is recommended for enhancing fruit yield and quality of greenhouse-grown red sweet pepper.
Hydroponics is a promising method for cultivation of saffron (Crocus sativus). In this study, saffron corms were sprouted using a gradual decrease in air temperature, and they were cultivated hydroponically in either perlite or volcanic rock for 24 weeks. A nutrient solution was supplied using either an ebb-and-flow system or continuous immersion. First blooming was observed 29 days after transplantation. Among flowering traits, only the stigma length was significantly influenced by the type of hydroponic system. Saffron plants displayed better growth parameters, a higher photosynthetic rate and stomatal conductance (gS), as well as daughter corm (cormlet) production under the continuous immersion system, in comparison with the ebb-and-flow system. Small corms (22–25 mm diameter) did not bloom, and the emergence of flowers increased with corm size. Plant growth and photosynthetic parameters, as well as cormlet production, significantly increased with corm size. We obtained the highest stigma yield [number of flowers (1.9), stigma length (39.4 mm), stigma fresh (42.8 mg), and dry weight (5.3 mg)] and cormlet yield [number of cormlets (5.7), average corm diameter (25 mm), and fresh weight (6.4 g)] using mother corms sized ≥32 mm diameter grown hydroponically in the volcanic rock–based continuous immersion system.
In vitro ovule culture could be used to generate homozygous lines through the production of haploid plants. The present study reports on in vitro regeneration and production of haploid plants through ovule cultures and identification of the regenerated haploids using flow cytometry. The ovules were cultured on Murashige and Skoog (MS) medium supplemented with different concentrations of 6-benzyladenine (BA), kinetin (Kin), 2,4-dichlorophenoxyacetic acid (2,4-D), and naphthalene acetic acid (NAA) at 0, 0.5, 1, and 2 mg·L−1 for their gynogenesis. Among different plant growth regulators (PGRs) tested, 2,4-D at 2 mg·L−1 produced direct gynogenesis. The highest callogenesis percentage (100%) was obtained on MS medium containing 1 mg·L−1 2,4-D and 2 mg·L−1 NAA. Flow cytometry analysis was used to identify the regenerated haploids. It also confirmed gynogenic occurrence at 1 and 2 mg·L−1 2,4-D with percentages of 21.7% and 41%, respectively. Therefore, 2,4-D proved effective for the induction of haploids in black cumin. The regenerated haploids were developed on MS medium without PGRs. The obtained results of in vitro gynogenesis and haploid plant production can tremendously facilitate breeding programs of black cumin.
A method for micropropagation of Conocarpus erectus through axillary shoot proliferation is presented. Shoot tips were excised from adult donor tree and cultured for 4 weeks on Murashige and Skoog’s (MS) medium supplemented with 3 mg·L−1 gibberellic acid (GA3) to induce sprouting of shoots and formation of axillary shoots. Conocarpus erectus shoots were cultured for 6 weeks on MS medium supplemented with different concentrations and combinations of plant growth regulators (PGRs) and proliferation of the shoots was monitored. The type and concentration of cytokinins applied had a significant influence on shoot proliferation responses. Supplementation with 6-benzylaminopurine (BAP) increased the rate of shoot proliferation compared with other cytokinins. The use of BAP in combination with auxins such as indole-3-butyric acid (IBA) and naphthalene acetic acid (NAA) resulted in an increased number of shoots per explant compared with treatment with BAP alone. A combination of 2 mg·L−1 BAP and 0.5 mg·L−1 IBA produced the highest number of axillary shoots (7.8 shoots/explant). The best rooting medium was full-strength MS medium supplemented with 1 mg·L−1 IBA; this treatment yielded 80% rooting with an average of 3.5 roots per plantlet. All regenerated plantlets were successfully acclimatized to greenhouse conditions.
For the first time, genetic diversity among 14 ornamental palm accessions originating from different countries and grown in different regions in Egypt were examined. Identification of genetic variation and phylogenetic relationships in ornamental palms would be useful for its genetic identification, improvement, and conservation. Genetic polymorphism was analyzed using the randomly amplified polymorphic DNA (RAPD) as well as protein markers. The electrophoretic pattern of protein analysis produced 21 bands distributed in all accessions with molecular sizes ranging from 11.8 to 99.3 KDa. Some accessions possessed some bands, which were absent in other accessions and could be used for their identification. Furthermore, 10 RAPD selected primers were employed to determine genetic variation among the 14 palm genotypes as well as to test the effectiveness of RAPD primers as a genetic marker. RAPD analysis revealed a high level of polymorphism (100%) among the studied accessions. A total number of 310 amplified bands were generated across the studied genotypes with an average of 30 bands per primer. Cluster analysis using sequence alignment was done to generate a dendrogram verifying the relationship among the 14 studied ornamental palms, with an average similarity matrix range of 0.00 to 0.08 and 0.39 to 0.93 for RAPD and protein markers, respectively. It is concluded that, both SDS-protein and RAPD markers are equally important for genetic analysis and are suitable for the characterization of ornamental palm collection.
Peppermint (Mentha piperita), sweet basil (Ocimum basilicum), and coriander (Coriandrum sativum) are important medicinal plants in the pharmacological industry. These plants are produced in commercial scale but their seeds exhibit low germination percentages under favorable germination conditions. Enhancing seed germination is thus crucial for improving the production of these plants. The influence of gibberellic acid (GA3), indole-3-acetic acid (IAA), indol-3-butyric acid (IBA), and naphthalene acetic acid (NAA) on seed germination of the three plants were investigated. The seeds were soaked in each plant growth regulator at 50, 100, and 150 mg·L−1 for 24 hours at 25 ± 2 °C. Seed germination was checked daily for 20 days and germination parameters including final germination percentage (FGP), corrected germination rate (CGRI), and number of days lapsed to reach 50% of FGP (GT50) were recorded. The phosphorus and protein contents were determined in germinated seedlings on day 21 of culture. All plant growth regulators enhanced seed germination as compared with control. However, GA3 improved seed germination more than IAA, IBA, and NAA. GA3 at 100 mg·L−1 significantly increased the FGP from 22.3% and 33.3% (control) to 74% and 65.6% for peppermint and sweet basil, respectively. Low concentration of GA3 at 50 mg·L−1 increased the FGP for coriander from 27% to 52.3%. GA3 also increased CGRI, GT50, phosphorus, and protein contents in germinated seedlings as compared with control. Seeds of peppermint, sweet basil, and coriander possess a physiological dormancy that could be elevated by GA3 presowing treatment. This study established a successful methodology for optimizing seed germination to satisfy the demand for the medicinal parts of these plants in the pharmacological industry.
Plant tissue culture offers opportunities for the rescue and conservation of endangered plant species. Here, we report the successful in vitro propagation of Dracaena ombet, an endangered plant. Several physical and chemical seed treatments were evaluated to develop a propagation approach. Germination of D. ombet seeds was monitored for 16 weeks by placing them onto Murashige and Skoog (MS) medium. Maximum seed germination (20%) was recorded when seeds were soaked-scarified, whereas all other treatments did not result in seed germination. Fragmented (longitudinally bisected) and intact in vitro shoots were cultured onto MS medium supplemented with various concentrations of 6-benzylaminopurine (BAP) and indole butyric acid (IBA) to induce axillary shoots. Longitudinal fragmentation of explants had a greater effect than the intact explants for shoot proliferation when cultured onto medium containing plant growth regulators. Fragmented shoots cultured onto MS medium supplemented with 2 mg·L−1 BAP and 0.5 mg·L−1 IBA treatment resulted in the highest amount of axillary shoots (seven shoots per explant). The intact shoots had the highest axillary shoots (1.8 shoots per explant) when cultured onto a medium supplemented with a combination of 1 mg·L−1 BAP and 0.5 mg·L−1 IBA. One hundred percent rooting was obtained using half strength MS medium supplemented with 0.5 or 1 mg·L−1 IBA. With full strength MS medium, a maximum rooting of 60% was obtained with 1 mg·L−1 IBA or naphthalene acetic acid (NAA) addition. The plantlets were acclimatized to ex vitro conditions with a 95% survival rate. This study offers a simple method for in vitro propagation of D. ombet, which is valuable to enable conservation of this endangered species.