Ulva ohnoi is a cosmopolitan green seaweed with commercial potential given the biomass that may be generated. We evaluated the effects of substrate changes induced by U. ohnoi application on the vegetative response of tomato plants under greenhouse conditions. First, the decomposition dynamics and N release of the dry seaweed biomass were studied using the litterbag method. Subsequently, we evaluated the effect of seaweed powder (SP) or seaweed extract (SE) applications on substrate and plant growth. Additionally, the growth parameters responses evaluated were related to the changes in substrate properties associated with each treatment. The results showed that the dry seaweed biomass has a rapid rate of degradation (k = 0.07 day⁻¹) and N release (k = 0.024 day⁻¹). The SP application improved the physicochemical and biological characteristics of the substrate by increasing the availability of minerals, the fungi:bacteria ratio, and the growth morphophysiological parameters (length, area, dry and fresh weight), chlorophyll and mineral content. In contrast, SE treatment showed a positive effect on the root, mineral content, and soil microbes. This study highlights the agricultural potential of U. ohnoi powder as an alternative supplement that supports nutrition and promotes the vegetative growth of plants cultivated in soilless horticultural systems.

Lippia graveolens, commonly known as Mexican oregano, is an aromatic plant of great industrial, nutritional, and medicinal value, principally for its essential oils. Regeneration via axillary buds was established in MS medium supplemented with 6-benzyladenine (BA) (0.5 mgL⁻¹) as a growth regulator. Three genotypes and three stages of cultivation were considered in the study. On average, 3.5, 4.2, and 6.4 shoots induced per explant were obtained for genotypes B, C, and D, respectively. Several doses (0.1, 0.3, and 0.5%) of ethyl methane sulfonate (EMS) and different exposure times (1, 2, and 3 h) were applied to investigate the effect of the chemical mutagen on the formation of axillary buds. Genetic variation among the collected plants, the micro-propagated plants during three sub-cultivations, and the plants regenerated in the presence of the mutagen was evaluated by means of randomly amplified microsatellite polymorphism (RAMP) markers. A high genetic stability was observed in the micro-propagation of Mexican oregano for the three genotypes and three sub-cultivations, presenting 100% of monomorphic bands. The genetic variation observed in the different collections of wild populations (A, R, and V) and after treatment with EMS regarded 34 and 35% of polymorphic loci, respectively.

The use of extracts derived from different plants has gained popularity as an alternative option to manage weeds and support phenological development in plants. One of the main problems facing agricultural production is the intensive application of chemical fertilizers that harm the environment. This study investigated the biostimulant effects of the aqueous extracts of Verbesinasphaerocephala and Verbesinafastigiata on the germination and growth of tomato (Solanum lycopersicum) and American cucumber (Cucumis sativus) seedlings. The aqueous extracts of both species of Verbesina were tested at concentrations of 0.5 and 1%. Seed germination and seedling development under nursery conditions were evaluated. The seed germination percentage was reduced in all treatments with the extracts of both Verbesina species when compared to that of the control treatment, which was considered an allelopathic effect. However, seedling growth in pots showed different behavior, with the extracts beneficially affecting certain agronomic variables, such as root and leaf length. The results suggest potential uses for V. sphaerocephala and V. fastigiata extracts, although a greater range of action may be experienced through the effects of certain molecules on weed growth. Additional studies with chemical approaches are necessary to better direct the uses and applications of Verbesina biomolecules, as they also functioned as growth promoters.

The hydrangea (Hydrangea macrophylla (Thunb). Ser.) is an ornamental species with great market potential. It is known for its ability to change the colour of its inflorescence, according to the pH of the culture substrate. The molecular mechanisms that underlie these changes are still unclear. It is known that epigenetic mechanisms, such as DNA methylation, play an important role in genetic expression, so they could be responsible for this phenomenon in hydrangea. In the present study, the molecular markers ISSR (Inter Simple Sequence Repeat) and MSAP (Methyl-Sensitive Amplification Polymorphism) were used to detect molecular changes in the genome of hydrangea plants that were cultivated under different pH levels to modify the colour of the sepals. The results showed a correspondence between the methylation signal measured with MSAP and amplification ISSR patterns when compared before and after the modification of pH culture substrates. These results suggest that DNA methylation might be involved as a molecular mechanism underlying the colour change of hydrangea sepals in response to a differential pH in the substrate. In addition, the results pave the way to study the relationship between DNA methylation and ISSR marker profiles.

Adaptation parameters as leaf width, leaf length, mesophyll thickness, number of adaxial and abaxial stomata, and biomass were measured in eight stonecrop species (Crassulaceaae), spider plant ( Chlorophytum comosum ), and maria’s heart ( Peperomia tepoztecoana ) in vertical greenery system (VGS) and containers (POT). Statistical significance among parameters was probed by t test and principal component analysis was performed to detect global morphological changes. Mexican gem ( Echeveria elegans ), graptosedum (× Graptosedum ‘Vera Higgins’), lavender scallops ( Kalanchoe fedtschenkoi ), coppertone sedum ( Sedum nussbaumerianum ), ghost plant ( Graptopetalum paraguayense ), and jelly-beans ( Sedum rubrotinctum ) were the species that did not change significantly their morphological traits during growth in the VGS. This provides evidence of the potential for these species to be used in green walls or any VGS while maintaining their characteristic shape and beauty. Graptopetalum ( Graptopetalum macdougalli ), gray sedum ( Sedum griseum ), maria’s heart, and spider plant showed changes in its morphology during growth in the VGS when compared with growth in POT, indicating a lower potential for adaption to VGS.

Daminozide (B-Nine) it is a plant growth regulator, is translocated from the leaves to the stem to avoid elongation and produce more compact plants and uniform growth and vigor. For the cultivation of Lisiathus the information of the damonizide application is scarce despite of great marketing potential, so the objective of this study was to evaluate the effect of daminozide on the vegetative growth and flowering of Lisianthus grown in pot. Granulated Lisianthus seeds were germinated and transplanted into pots under nursery conditions. Three foliar applications of daminozide were realized; two applications in vegetative stage and one in flowering, adding three concentrations in each of them (0.5, 1.0 and 1.5 ml L–1) were used and water was applied as a control during the vegetative and flowering phases. The applications of daminozide at 1.0 and 1.5 ml L–1 were optimal for the vegetative development in Lisianthus (plant height – 15 cm, size of the internodes – 2.5 cm, number of branches – 3, width and length of the leaves – 3 cm and 6.5 cm), while the dose of 0.5 ml L–1 was favorable for all flowering stages (beginning of flowering – 182 buttons, sepals closed and larger than the petals – 53), visible petals larger than the sepals – 25, floral opening and full flowering – 3 flowers per plant). Based on these results, the application of B-Nine at low concentrations (0.5 and 1 ml L–1) is recommended for the development of Lisianthus in pots.