Efficient Plant Regeneration via Indirect Organogenesis in Carnation (Dianthus Caryophyllus Semperflorens flore pleno) Cultivars

ABSTRACT Callus induction and plant regeneration are important steps of in vitro plant breeding of ornamental plants. In this study, the effects of different combinations of plant growth regulators (PGRs), promoters, and minerals on callus induction and plant regeneration in different carnation cultivars were studied in a completely randomized design with three replications. For callus induction, 16 different combinations of 2,4-dichlorophenoxyacetic acid (2,4-D), 6-benzylaminopurine (BA), 1-naphthaleneacetic acid (NAA), and casein hydrolysate (CH) were studied using in vitro leaf explants. The Murashige and Skoog (MS) medium supplemented with 0.2 mg·dm-3 of 2,4-D and 200 mg·dm-3 of CH showed the highest frequency of callus induction. Among the cultivars, ‘Noblesse’ showed the highest rate of callus induction (91.67%). Regarding regeneration, BA, NAA, silver nitrate (AgNO3), and adenine hemisulfate (As) were used in ten different combinations. The ‘Cameron’, ‘Tabasco’, and ‘Noblesse’ cultivars with 95.24% regeneration percentage showed the highest rate of plant regeneration. Generally, in most cultivars, the highest regeneration rate and shoot number per explant were found in the MS medium supplemented with 3 mg·dm-3 of BA, 0.6 mg·dm-3 of NAA, 5 mg·dm-3 of AgNO3, and 40 mg·dm-3 of As. According to the results, the highest regeneration frequency was obtained when 40 mg·dm-3 of As was added to the medium. Finally, the flow cytometry analysis indicated that there were no significant differences between in vitro regenerated and control plants in terms of DNA ratios.

Relationship of Resistance-Related Enzyme activity and Salicylic Acid content in Phalaenopsis Species with different levels of resistance to DIckeya Dadantii

ABSTRACT Orchids (Phalaenopsis) are ornamental plants that are cultivated commercially and in great demand in the market. Soft-rot disease (SRD) caused by the necrotrophic pathogen Dickeya dadantii is a cause of considerable economic loss to cultivators of many orchid species. Our previous experiment identified a limited number of species that were resistant to D. dadantii. This study aimed to validate the resistance level of four Phalaenopsis species in a detached leaf inoculation protocol to identify the resistance mechanism(s) involved. Soft-rot symptom diameter was measured from 6 to 18 hours post-inoculation (HPI) with D. dadantii. Disease assessment confirmed that P. amboinensis is a resistant species, P. pantherina is a susceptible species, and P. amabilis and P. schilleriana are very susceptible species. There was no difference in the lignin content between the resistant and very susceptible species. Detailed observation of resistant and very susceptible species, P. amboinensis vs. P. amabilis, revealed higher phenylalanine ammonia-lyase (PAL) and peroxidase (POD) in P. amabilis than in P. amboinensis. In contrast, there was higher salicylic acid (SA) content in P. amboinensis than in P. amabilis. These results suggest that POD and PAL activities may not be effective in defense against soft-rot disease, while SA plays an important role in the resistance of P. amboinensis to D. dadantii. Low PAL activity in P. amboinensis implies that the SA contents from the isochorismate pathway may be involved in the mechanism of P. amboinensis resistance to D. dadantii. Therefore, endogenous SA content may be a good indicator for screening resistant species in Phalaenopsis.

Application of ImageJ Software in the assessment of flowering Intensity and growth Vigor of pear Trees

The study evaluated the possibility of using the image acquisition and processing method with ImageJ software for estimating growth vigor and flowering intensity of ‘Conference’ pear trees. For assessing flowering intensity, manual counting of flower clusters and taking of photographs of the trees were conducted at full bloom. Tree vigor was estimated by manually measuring the total length of the central leader and shoots of individual trees. The trees were photographed from the same distance using a hand-held camera. The calibration model for assessing the vigor or flowering of trees by image analysis was based on measurements and photographs taken for nine selected trees differing in the total length of shoots or in the number of flower clusters. Then, a quality assessment of the model was carried out on 26 nonselected trees. Image processing was performed using ImageJ software. High regression coefficients were obtained between the surface area of petals measured on the photographs and the number of inflorescences counted (r2 = 0.98); however, observations carried out in the following year indicate the need for individual calibration of estimation models in each evaluation season. Subsequently, the quality of estimating the flowering intensity of pear trees was assessed using a previously determined calibration model. Mean absolute percentage error (MAPE) values ranged from 14.0% to 21.8%, depending on the measurement time. In the assessment of tree growth vigor, a high correlation (r2 = 0.98) was also obtained between the actual length of shoots measured individually for each tree and the values obtained by analyzing the photographic image, where the MAPE error was 12.9%.

Interaction of Light Intensity and CO2 Concentration Alters Biomass Partitioning in Chrysanthemum

Biomass partitioning is one of the pivotal determinants of crop growth management, which is influenced by environmental cues. Light and CO2 are the main drivers of photosynthesis and biomass production in plants. In this study, the effects of CO2 levels: ambient 400 ppm (a[CO2]) and elevated to 1,000 ppm (e[CO2]) and different light intensities (75, 150, 300, 600 μmol·m−2·s−1 photosynthetic photon flux density – PPFD) were studied on the growth, yield, and biomass partitioning in chrysanthemum plants. The plants grown at higher light intensity had a higher dry weight (DW) of both the vegetative and floral organs. e[CO2] diminished the stimulating effect of more intensive light on the DW of vegetative organs, although it positively influenced inflorescence DW. The flowering time in plants grown at e[CO2] and light intensity of 600 μmol·m−2·s−1 occurred earlier than that of plants grown at a[CO2]. An increase in light intensity induced the allocation of biomass to inflorescence and e[CO2] enhanced the increasing effect of light on the partitioning of biomass toward the inflorescence. In both CO2 concentrations, the highest specific leaf area (SLA) was detected under the lowest light intensity, especially in plants grown at e[CO2]. In conclusion, elevated light intensity and CO2 direct the biomass toward inflorescence in chrysanthemum plants.

Rooting Responses of Female and Male Cuttings of Leucadendron elimense E. Phillips subsp. elimense on the Type and Concentration of Auxin

Female and male plants of difficult-to-root species Leucadendron elimense subsp. elimense were investigated for rooting potential with three rooting hormones: indole-3-acetic acid (IAA), 1-naphthaleneacetic acid (NAA), and indole-3-butyric acid (IBA) at three different concentrations (2000 ppm, 4000 ppm, and 6000 ppm). The experiment was made under essential misting, bottom heat, and a naturally ventilated greenhouse. After 18 weeks the experiment terminated and callusing and rooting percentage, root number, and root length were determined. Female cuttings rooted in the highest percentage (80%), root number (>30), and root length (close to 100 mm) after treatment with IAA at 4000 ppm. Under the above treatment male cuttings rooted in 70%, with a mean root number of 24 and root length of 90 mm. The efficient rooting results could aid in saving the species in its natural habitat and supporting restoration ecology, as well as introducing this species into the flower market.

The Influence of Biostimulants on Tomato Plants Cultivated under Hydroponic Systems

Two biostimulants, RutfarmMaxifol (Ascophyllum nodosum extract 17.5%, amino acids, macro- and microelements, Agromaster, Russia) and Radifarm (polysaccharides, glycosides, amino acids, and micro-elements; Valagro, Italy), were applied at different concentrations on tomato plants of the hybrid cultivar ‘Merlice’, grown under a hydroponic system. Biostimulants were applied in the form of seed soaking and twice as foliar sprayings at flowering and at the initial fruit development stages. Biostimulants were applied as water solutions at concentrations of 2.5, 5.0, and 7.5 mg·L−1. Plant growth, productivity, and fruit quality parameters were determined at three points: 35, 70, and 105 days after seeding. All biostimulant treatments resulted in higher values of growth parameters and yield productivity in relation to the control. The application of biostimulants improved the parameters of the fruits’ quality by increasing the total soluble solids and antioxidants, ascorbic acid, and carotenoid contents but it did not affect tomato fruit acidity; therefore, tomato fruits from the treated plants were tastier than those from control.

Seed Source Effects on Germination, Growth, and Yield of Carrots Under Natural Farming

Natural farming is a type of low-input sustainable agricultural system that is characterized by the avoidance of the use of any animal materials. Production of self-produced seeds by farmers is recommended under natural farming environments, with an expectation of improved crop growth and yield. However, there have been no scientific studies that investigated the performance of self-produced seeds under natural farming. This study investigated the germination rate, growth, and yield of carrots (Daucus carota L.) from different seed sources under natural farming. The main experimental factor was the cultivation method: CT – control; CF – conventional farming; NF1 – natural farming with tillage and compost input; and NF2 – natural farming without tillage and compost, and the subfactor was the seed source: OPN – open-pollinated seeds self-produced under natural farming; OPC – open-pollinated seeds produced under conventional farming; and HB – hybrid seeds. The germination rate of OPN seeds was higher than that of other seeds. In addition, root fresh weight and other root parameters of OPN were as high as for HB seeds. This suggests that using self-produced seeds by farmers improves crop performance in a natural farming system.

Understanding Phenological Stages of Pomegranates vis-à-vis Flowering and Fruiting Regulation

A thorough understanding of plant behavior at different growth stages is of paramount importance for fruit quality improvement, the regulation of production periods, and reduced fruit production costs. There are as many as three waves of flowering in evergreen pomegranate cultivars – i.e., during the spring, rainy, and autumn seasons. However, for securing enhanced production of superior quality fruits as well as profit to the growers, crop regulation is required. This can be achieved by forcing the tree to rest at a particular stage and by producing abundant blossoming and quality fruits during any one of the three flushes. Observations on phenological phases would help in understanding the dates of specific stages of crop development, which in turn enable the growers to plan, organize, and carry out timely schedules of agronomic practices such as irrigation, fertilization, and crop protection. Therefore, there is a need to evaluate the response of pomegranate under different environmental conditions to identify a suitable flowering season to produce a better quality of fruits with consistent yield, and to enable standardization of management practices for optimum production based on phenological stages.

Effect of Planting Time and Corms Treatment with Gibberellic Acid on Growth, Flowering, and Vase Life of Freesia hybrida ‘Corona’

Freesia hybrida is one of the most important cut flowers with a short vase life. The present study was conducted to explain the effect of the two planting dates December 1st and 15th and soaking corms before planting in gibberellic acid at concentrations of 0, 75, and 150 mg·L−1 on the growth, flowering, and flowers quality of Freesia hybrida ‘Corona’. A larger diameter of the inflorescence stem and floret head, fresh weight of inflorescence, and longer vase life were obtained when planted on December 1st. Soaking the corms in a GA3 solution of 150 mg·L−1 before planting significantly extended the vase life compared to the control. Finally, it can be concluded that the planting of corms soaked in a solution of 150 mg·L−1 GA3 on December 1st in unheated greenhouses can improve the growth, development, and quality of flowers of Freesia hybrida ‘Corona’.

Red and Blue Light-Emitting Diodes Significantly Improve in vitro Tuberization of Potato (Solanum tuberosum L.)

The tuberization phenomenon in potatoes (Solanum tuberosum L.) is a highly synchronized morphophysiological process occurring on the underground stolons under the influence of various intrinsic and extrinsic factors. This involves the participation of the phytochrome sensory system, transport of sucrose from source to stolon, and several regulatory pathways including tuber-inducing hormone biosynthetic lipoxygenase (StLOX1) gene and major calcium-mediated signaling pathway genes (StCDPK and StCaM1). This study was aimed to explore the impacts of distinctive qualities of the light-emitting diode (LED) light with a specific wavelength on in vitro tuberization of potato. Single nodal segments of potato ‘Kufri Jyoti’ were incubated in vitro on the growth medium at a temperature of 22 ± 2 °C and exposed to various combinations of red (R) and blue (B) LED light. The results showed that the combination of 30% red + 70% blue LED light (R30B70) significantly shortened the tuber induction period, increased the number of tubers, and their yield compared with these parameters in the tissues exposed to the white light (W100). The induction of the in vitro tuberization correlated with the enhanced expression of the major tuberizing pathway genes, including the lipoxygenase (StLOX1), calmodulin (CaM1), and calcium-dependent protein kinase (StCDPK). The current study indicated that the combination of red and blue LED lights at R30B70 is the best spectrum for effective in vitro tuberization of potatoes.