Seed Dormancy Class and Ecophysiological Features of Veronicastrum sibiricum (L.) Pennell (Scrophulariaceae) Native to the Korea Peninsula

Veronicastrum sibiricum is a perennial species distributed in Korea, Japan, Manchuria, China, and Siberia. This study aimed to determine the requirements for germination and dormancy break of V. sibiricum seeds and to classify the kind of seed dormancy. Additionally, its class of dormancy was compared with other Veronicastrum and Veronica species. V. sibiricum seeds were permeable to water and had a mature embryo during seed dispersal. In field conditions, germination was prevented by physiological dormancy, which was, however, relieved by March of the next year, allowing the start of germination when suitable environmental conditions occurred. In laboratory experiments, the seeds treated with 0, 2, 4, 8, and 12 weeks of cold stratification (4 °C) germinated to 0, 79, 75, 72, and 66%, respectively. After the GA3 treatment (2.887 mM), ≥90% of the seeds germinated during the four incubation weeks at 20/10 °C. Thus, 2.887 mM GA3 and at least two weeks at 4 °C were effective in breaking physiological dormancy and initiating germination. Therefore, the V. sibiricum seeds showed non-deep physiological dormancy (PD). Previous research, which determined seed dormancy classes, revealed that Veronica taxa have PD, morphological (MD), or morphophysiological seed dormancy (MPD). The differences in the seed dormancy classes in the Veronicastrum-Veronica clade suggested that seed dormancy traits had diverged. The results provide important data for the evolutionary ecological studies of seed dormancy and seed-based mass propagation of V. sibiricum.

Micropropagation of lavender: a protocol for production of plantlets

ABSTRACT Lavender (Lavandula dentata) has several medicinal applications, both in the fresh form and after industrial processing. Productivity increase could be obtained through the mass propagation, expanding the possibility of obtaining raw material for production of essential oil. The objective of this work was to develop a micropropagation protocol from explants obtained from seeds. Aspects of in vitro germination, multiplication, elongation and rooting were evaluated and, in sequence, the acclimatization process as well. The in vitro germination of lavender seeds can be obtained using a medium composed of agar and water. For multiplication, the use of MS medium (Murashige & Skoog, 1962) added with 5.0 µM 6-benzylaminopurine to the nutrient medium is the most appropriate. For elongation and rooting, the use of growth regulators is unnecessary. Acclimatization can be obtained directly by transferring the explant to plastic bags with substrate, kept in a greenhouse. It was possible to develop a protocol for the in vitro cultivation (establishment, multiplication, elongation, rooting and acclimatization) of lavender from explants of seed origin.

Expression pattern of in vitro organogenesis-associated genes as transcriptional marker in Indian Sandalwood (Santalum album L.).

Indian sandalwood (Santalum album L.) is an expensive wood that requires reproducible method for mass propagation to ensure consistent production and sustainable use of sandalwood. For mass propagation of sandalwood, plant organogenesis requires different combinations of the tissue culture medium. The media is composed of exogenous phytohormones which decides the explant's morphological stages such as shooting or rooting induction. Early prediction of morphological stage from explant can potentially help in selecting the exogenous phytohormones combinations thereby saving time and resources for mass sandalwood propogation. An efficient protocol for the direct and indirect organogenesis (up to shooting development phase) of sandalwood were developed using Woody Plant Media (WPM). WPM supplemented with various concentrations of 6-Bezylaminopurine (BAP) and 1-Naphthaleneacetic acid (NAA) were tested for direct organogenesis, while different treatments consisting of various levels of 2,4-dichlorophenoxyacetic acid (2,4-D), NAA, BAP, Adenine sulphate (ADS), glycine and potassium nitrate were tested for indirect organogenesis. Three stages of leaf development were selected viz., the leaf just after inoculation in WPM media, initial stage of callus formation from leaf and shoot formation for expression pattern analysis. The targeted genes were Alternative oxidase (ao), Late embryogenesis abundant (lea), Cytochrome P450 (cyt-p450), ABC transporter (abct), and Serine-threonine phosphatase (stp) which are associated with in vitro organogenesis. The expression patterns were evaluated to identify a transcription marker. During the initial stages of organogenesis, ao, cyt-p450 and abct showed no/little change in expression in the direct pathway but up-regulation of ao and abct and downregulation of cyt-p450 were observed in the indirect pathway. Expression of lea was increased up to 70-fold during direct and dropped to half during indirect organogenesis.

MICROCLONAL PROPAGATION OF SPIRAEA JAPONICA FOR LANDSCAPING

Japanese spiraea (Spiraea japonica) is an ornamental shrub widely used in landscaping. The method of clonal micropropagation of Spiraea japonica was optimized to obtain a large number of plants from several shoots. The optimal concentrations of hormones have been established to increase multiplication and root formation. QL medium with 0,5 mg/l benzyl aminopurine (BAP) in combination with 1,0 mg/l gibberelic acid (GA); 0,01 and 1,0 mg/l indolyl butyric acid (IBA); 1,0 mg/l of naphthyl acetic acid (NAA) were tested for multiplication. For root induction, naphthyl acetic acid (NAA) was used in five doses at half the concentration of QL and MS medium. The highest multiplication of shoots (14,02±1,39) and the highest increase in shoot length (6,39) was obtained on QL medium supplemented with 0,5 mg/l BAP; 1,0 mg/l GA and IBA 0,01 mg/l. The highest rooting (100%), the maximum number of roots (6,20±0,63), the length of the longest root (4,60±0,02) was observed on ½ QL medium containing 0,1 mg/l NAA. In conclusion, for Spiraea japonica, an efficient high speed and rooting protocol is described that can be used in mass propagation.

Evaluation of substrate composition and exogenous hormone application on vegetative propagule rooting success of essential oil hemp (Cannabis sativa L.)

To support the rapidly expanding industrial hemp industry, a commercial supply of high-quality starter plants with low genetic variability from nurseries will be key to consistent and efficient cultivation efforts. Rooting success was evaluated across four propagation medias, five rooting hormones, and eight commercially available high-cannabidiol (CBD) essential oil hemp cultivars. Cuttings were placed in a climate-controlled room and assessed for rooting success 12 days after cloning. Rooting success was determined by quantifying total root number, cumulative total root length, and total root mass. Propagation media had the greatest effect on rooting success (13–80%). Rockwool had the highest rooting success resulting in 10-fold increases in rooting traits over the next highest scoring medium (Berger BM6). Hormone applications significantly improved (15- to 18-fold) rooting success compared to no hormone application, while non-statistical differences were observed across auxin hormone concentrations and application methods. Genetic variation in rooting response was observed between cultivars with ‘Cherry Wine’ outperforming all other cultivars with an approximate 20% increase in rooting success over the next highest rooting cultivar, ‘Wife’. Although the ideal combination was not specifically identified in this study, findings provide insight into how rooting hormone application and medium selection impact vegetative propagule rooting success of essential oil hemp.