Thigmomorphogenesis (or mechanical stimulation-MS) is a term created by Jaffe and means plant response to natural stimuli such as the blow of the wind, strong rain, or touch, resulting in a decrease in length and an increase of branching as well as an increase in the activity of axillary buds. MS is very well known in plant morphology, but physiological processes controlling plant growth are not well discovered yet. In the current study, we tried to find an answer to the question if MS truly may affect auxin synthesis or transport in the early stage of plant growth, and which physiological factors may be responsible for growth arrest in petunia. According to the results of current research, we noticed that MS affects plant growth but does not block auxin transport from the apical bud. MS arrests IAA and GA₃ synthesis in MS-treated plants over the longer term. The main factor responsible for the thickening of cell walls and the same strengthening of vascular tissues and growth arrestment, in this case, is peroxidase (POX) activity, but special attention should be also paid to AGPs as signaling molecules which also are directly involved in growth regulation as well as in cell wall modifications.

Thigmomorphogenesis denotes a suite of anatomical, physiological, biochemical, biophysical, and molecular responses of plants to mechanical stimulation. This phenomenon is evolutionarily conserved among diverse plant lineages; however, the magnitude and character of the response are strongly determined by both the frequency and intensity of the applied stimulus. In angiosperms, thigmomorphogenetic reactions typically occur gradually, reflecting a complex interplay of morphological alterations, biochemical adjustments, and genetic reprogramming. In dicotyledonous plants, thigmomorphogenesis is commonly expressed as a reduction in leaf blade surface area, shortening of petioles, decreased plant height, radial thickening of stems, and modifications in root system architecture. In monocotyledons, in turn, mechanical stress frequently results in stem rupture below the inflorescence, with concomitant shortening and increased flexibility of younger internodes. These specific traits can be explained by structural features of monocot secondary walls as well as by the absence of vascular cambium and lateral meristems. Mechanical stimulation has been shown to initiate a cascade of responses across multiple levels of plant organization. The earliest events involve activation of mechanoresponsive genes (e.g., TCH family), followed by enzymatic activation, biochemical shifts, and downstream physiological and molecular adjustments. Importantly, recent findings indicate that prolonged mechanical stress may significantly suppress auxin biosynthesis, while leaving auxin transport processes unaffected. Moreover, strong interdependencies have been identified between thigmostimulation, gibberellin biosynthesis, and flowering intensity, as well as between mechanical stress and signaling pathways of other phytohormones, including abscisic acid, jasmonic acid, and ethylene. At the molecular scale, studies have demonstrated a robust correlation between the expression of specific calmodulin isoforms and the GH3.1 gene, suggesting a mechanistic link between mechanosensing, hormone homeostasis, and regulatory feedback loops. The present study consolidates current knowledge and integrates novel findings, emphasizing both morphological and cellular dimensions of thigmomorphogenesis. In particular, it provides evidence that mechanical stress constitutes a critical modulator of hormonal balance, thereby shaping plant growth, development, and adaptive potential.

Water management in agriculture and horticulture has a strong ecological importance related to the necessity of optimizing the use of water resources. To achieve sustainable water use, it is necessary to optimize the time, frequency and the methods of water application. In this study, we hypothesized that the right moment for watering may be established on the grounds of the observation of the physiological state of the plant (if the plant is still in turgor) and the biomass of plant and the substrate. The proper irrigation scheduling, that is, just before the plant loses turgor, which appears at ca. 73% of LRWC in dahlias, determined with the use of the proposed measurement and computing system, makes it possible to save ca. 30% of irrigation water, in comparison to standard watering. Controlled watering also affected plant growth parameters, such as the content of chlorophyll a and b and carotenoid, as well as total and reducing sugar content (ca. 7%, 9% and 23% more than in plants watered in a standard way, respectively). Plants watered in a controlled way were 12% more compact when compared with the ones watered in a standard way. The results clearly proved that the computing system connected to scales made it possible to save water used for irrigation without a negative impact on the parameters of plant growth.

In 1973, Jaffe identified and characterized the phenomenon of thigmomorphogenesis, also referred to as mechanical stress (MS) or mechanical stimulation in plants. Previous studies on petunia plants demonstrated that MS significantly affects growth dynamics. As a response to MS, petunias exhibit increased levels of indole-3-acetic acid (IAA) oxidase and peroxidase, although the active transport of endogenous IAA remains unaffected. Furthermore, earlier research has shown that MS inhibits the synthesis of IAA and gibberellin (GA₃), with noticeable effects on the 14th day of mechanical stimulation. The current experiment made on Petunia × atkinsiana 'Pegasus Special Burgundy Bicolor’ focused on evaluating the morphological and physiological responses to MS, along with the expression of specific touch-responsive genes such as GH3.1, which is involved in auxin metabolism, and calmodulins (CaMs), playing an important role in stress responses. GH3.1 expression was found to be negatively correlated with IAA synthesis while positively correlated with GAs synthesis and IAA oxidase activity. Variable expression patterns were observed in the calmodulins: CAM53 and CAM81 expression positively correlated with IAA synthesis and plant height, whereas CAM72 expression was positively associated with GAs levels and IAA oxidase activity in plants touched 80× per day, but all of them were negatively related to IAA content and shoot increment, while positively related to GAs synthesis and IAA oxidase activity.

Orobanche lutea (Orobanchaceae) is an oligophagous holoparasite that attacks the root systems of plants from the Fabaceae family. It parasitizes mainly on Medicago falcata, occasionally also on M. sativa and M. ×varia. A previously unknown locality of Orobanche lutea was discovered in abandoned limestone quarry “Góra Leśna”, near Starochęciny village in southern part of the Wyżyna Kielecko-Sandomierska upland in south-central Poland (Figs 1, 2). One noted individual of O. lutea was accompanied by species typical of dry and thermophilous habitats. In ATPOL square EE 83, where the individual was discovered, 10 localities of O. lutea have been reported so far. Threats to the site’s existence may include an extremely low population size (only one flowering individual), vandalism resulting from the quarry being used for recreational purposes (e.g., campfires), illegal waste dumping, and vegetation succession. The discovery of a relatively rare taxon indicates the need for further floristic studies at the above-mentioned locality and in other old quarries in the surrounding area.