PHYSICAL EUSTRESSORS AS POTENTIAL TOOLS TO IMPROVE CROP STRESS TOLERANCE (REVIEW)

Background. The processes occurring in plants and their seeds under stress, as well as the defense mechanisms used by plants under stress, are poorly understood, which makes it impossible to use them to increase yields. Purpose. Review and analysis of scientific publications, devoted to the phenomenon of stress memory acquired by plants as a result of physical stressors on their seeds and possible applications of this phenomenon in plant growing and crop breeding. Materials and methods. A selection and systematic review of scientific articles on the research topic for the period 2016-2023 was performed. The study consisted of the following steps: research literature search, evaluation and selection, data synthesis and analysis. Results. The use of hormetic effects of physical agents to stimulate seed germination of crops is effective. Responses to abiotic stresses could be 'trained' by priming so that the plant becomes better able to cope with later stress. Evidence of short-term and transgenerational memory formation following plant priming has been obtained. An epigenetic mechanism for the formation of long-term stress memory in plants as a result of a physical eustressor has been identified. The eustressor induces specific epigenetic marks associated with environmental adaptation, forming a new stress-resistant plant phenotype. Physical eustressors have the potential to impart stress tolerance to crops to enhance phenotypic characteristics to prevent yield losses. Conclusion. Seed treatment with physical stressors builds plant tolerance and memory to abiotic stresses, but scientific evidence on this issue is incomplete and sketchy. The understanding and application of stress memory for breeding purposes is currently limited, but it has great potential for the development of new crop varieties

Nature of the diffuse emission sources in the H I supershell in the galaxy IC 1613

We present a study of the nearby low-metallicity dwarf galaxy IC 1613, focusing on the search for massive stars and related feedback processes, as well as for faint supernova remnants (SNR) in late stages of evolution. We obtained the deepest images of IC 1613 in the narrow-band H{\alpha}, He II and [S II] emission lines and new long-slit spectroscopy observations using several facilities (6-m BTA, 2.5m SAI MSU, and 150RTT telescopes), in combination with the multi-wavelength archival data from MUSE/VLT, VLA, XMM-Newton, and Swift/XRT. Our deep narrow-band photometry identifies several faint shells in the galaxy, and we further investigate their physical characteristics with the new long-slit spectroscopy observations and the archival multi-wavelength data. Based on energy balance calculations and assumptions about their possible nature, we propose that one of the shells is a possible remnant of a supernova explosion. We study five out of eight Wolf-Rayet (WR) star candidates previously published for this galaxy using the He ii emission line mapping, MUSE/VLT archival spectra, and new long-slit spectra. Our analysis discards the considered WR candidates and finds no new ones. We found P Cyg profiles in H{\alpha} line in two stars, which we classify as Luminous Blue Variable (LBV) star candidates. Overall, the galaxy IC 1613 may have a lower rate of WR star formation than previously suggested

Magnetoelectric metglas/bidomain y + 140°-cut lithium niobate composite for sensing fT magnetic fields

We investigated the magnetoelectric properties of a new laminate composite material based on y+140°-cut congruent lithium niobate piezoelectric plates with an antiparallel polarized “head-to-head” bidomain structure and metglas used as a magnetostrictive layer. A series of bidomain lithium niobate crystals were prepared by annealing under conditions of Li2O outdiffusion from LiNbO3 with a resultant growth of an inversion domain. The measured quasi-static magnetoelectric coupling coefficient achieved |αE31| = 1.9 V·(cm·Oe)–1. At a bending resonance frequency of 6862 Hz, we found a giant |αE31| value up to 1704 V·(cm·Oe)–1. Furthermore, the equivalent magnetic noise spectral density of the investigated composite material was only 92 fT/Hz1/2, a record value for such a low operation frequency. The magnetic-field detection limit of the laminated composite was found to be as low as 200 fT in direct measurements without any additional shielding from external noises.publishe