We show that Einstein’s relativistic mirror with long (hundreds of µ m) propagation distance and controllable propagation velocity can be implemented in the form of a dense free carrier front ...generated by multiphoton absorption of tilted-pulse-front femtosecond laser pulses in a dielectric or semiconductor medium. The velocity control is achieved by varying the pulse front tilt angle. Simulations demonstrate that such fronts can serve as efficient Doppler-type converters of terahertz pulses. In particular, the pulse reflected from a front, generated by three-photon absorption of a Ti:sapphire laser in ZnS, can exhibit strong (up to more than an order of magnitude) pulse compression and spectrum broadening without a noticeable amplitude change. The proposed technique may be used to convert strong low-frequency terahertz pulses, generated by optical rectification of tilted-pulse-front laser pulses, to desirable temporal and spectral characteristics for a variety of applications.
The aim of this research is to identify and recommend for production or practical breeding varieties and hybrid potato material of various genetic and geographical origin, combining high yield, field ...resistance to mosaic viruses, and adaptability to stressful abiotic environmental factors, as well as to optimize and improve the efficiency of field evaluation of potato varieties. The research was carried out in 2019–2021 in Bezenchuksky raion of Samara oblast. The year 2019 was characterized by a spring drought, while 2020 and 2021 by spring–summer droughts. The hydrothermal coefficients for these years were 0.45, 0.47, and 0.61, respectively. In conditions of high temperatures and insufficient moisture, 36 new and promising potato varieties of domestic selection were evaluated according to a complex of economically valuable characteristics. The standards for the corresponding maturity groups are the varieties of Gala (medium-early), Zhigulevskii (midseason), and Udacha (early-season). The experimental material was planted in four repetitions; the number of plants in each repetition was 50. The predecessor was spring wheat. The soil of the experimental site was terraced chernozem, ordinary, low-humus, medium-thick, heavy loamy. The increased yields in the medium-early group were obtained for the varieties Krasa Meshchery, Debut, and Sudarynya, which exceeded Gala standard by 9.9, 4.8, and 2.8 t/ha, respectively. The increased yields in the midseason varieties are Siverskii and Alaska (8.6 and 5.0 t/ha higher than Zhigulevskii standard, respectively), while the Terra variety was in the early-season group (5.0 t/ha above the standard Udacha). The same varieties have high levels of field virus resistance (seven to nine points) to the most harmful X and Y viruses in the conditions of the Middle Volga region. Three main components that have the most significant impact on the variability of the studied parameters have been identified. It is shown that field virus resistance is the main limiting factor of yield for the studied set of varieties under conditions of elevated air temperatures and insufficient humidification. The share of the first component accounted for 34.6% of the variation of signs. It includes, with maximum loads of –0.801, –0.640, and –0.604, the yield and resistance to potato viruses X, and S and M, respectively.
The purpose of the study is to identify the relationship between drought resistance indicators and the yield of potato plants under unfavorable conditions. A xeromorphic leaf structure is considered ...to be a diagnostic sign of plant drought resistance. The objects of the study were 24 potato varieties. Planting of seeds, preplanting tillage, harvesting, and crop recording were carried out in the period of 2020–2022 on the territory of the Samara Research Institute of Agriculture (branch of the Samara Scientific Center, Russian Academy of Sciences). Growing conditions for 2021 and 2022 were characterized by elevated temperatures and insufficient moisture. The number and size of stomata per unit leaf area were chosen as the criterion for xeromorphism. The studied varieties were divided into two groups (
n
= 12 each) according to the number of stomata. In the first group, the average number of stomata was 26 000 pcs./cm
2
of leaf, and that in the second group was 35 000 pcs. (
F
= 41,
p
= 0.03). More developed structural features of xeromorphism and the accumulation of certain types of metabolites in the second group of varieties led to a 1.6 times greater yield than in the first less xeromorphic group (
F
= 9,
p
= 0.004). The second group was characterized by a large number of mesophyll cells per unit leaf area (584 000 pcs./cm
2
vs. 557 000 pcs.), high content of phospholipids (36 mg/g dry weight vs. 31 mg/g), dry weight (0.19 vs. 0.17 g/g wet weight), and the ratio of membrane lipids to membrane proteins (1.4 vs. 1.2). In the less xeromorphic group of plants, the level of oxidative stress, assessed by LPO products, was 0.050 μM/g fresh weight and was 12% higher than in the more xeromorphic group (
F
= 6,
p
= 0.08). The revealed positive correlation between yield and xeromorphic genotypes indicates the prospects of using this criterion in potato breeding or creating a variety model.
The ionization front of a cosmic ray air shower propagates in the atmosphere with almost the speed of light in vacuum, i.e., faster than a radio wave in the air. There can be no reflection of a radar ...signal from such a front. Instead, an additional transmitted wave, which travels behind the front in the backward direction, is generated. We study the frequencies, propagation directions, and amplitudes for the waves excited at the front and discuss their use for radar detection of air showers.
The contribution of the morpho-physiological parameters of leaves and tubers of 22 potato varieties (
Solanum tuberosum
L.) to the formation of yield under conditions of insufficient soil moisture ...and high air temperatures is studied. Discriminant analysis found that the stomata size (12%), chlorophyll content (10%), number of tubers (29%), and average tuber weight (21%) determined the gradation of plants by yield. The specific surface density of leaves (38%), the content of chlorophyll (13%) and carotenoids (13%), and the leaf area (12%) made the greatest contribution to discrimination in relation to ecological plasticity. It is concluded that the number of stomata per unit area of the leaf, the specific surface density of the leaf, and the content of photosynthetic pigments are the key characteristics that contribute to both the high yield and the adaptive capacity of potatoes.
We show that the highly relativistic motion of an extensive air shower allows one to increase the wavelength of the radar signal above its transverse size without giving rise to signal scattering. ...This increases the efficiency of detection due to an increase in the reflection from the shower and a lower level of sky noise in the frequency range of the reflected signal.
Twenty-four potato (
Solanum tuberosum
L.) varieties differing in ripening groups (early, middle-early, and mid-season-ripening) were studied. Potatoes were grown under the conditions of the Middle ...Volga region of Russia in 2019–2021. It was found statistically that the yield (t/ha) of the early and mid-season-ripening varieties was negatively correlated with the increase in average temperatures during the growing season from May to August (
R
= –0.97,
p
= 0.04). Soil moisture content at a depth of 20 cm was positively correlated with the yield of middle-early varieties (
R
= 0.97,
p
= 0.04). The average tuber weight in the early varieties was sensitive to the increase in average temperatures (
R
= –0.95,
p
= 0.04). An increase in soil moisture content was beneficial to the average tuber weight (
R
= 0.98,
p
= 0.04), though only in the middle-early and mid-season-ripening groups. However, the soil moisture content and the tuber numbers in the mid-season-ripening varieties were negatively correlated (
R
= –0.96,
p
= 0.05).
We revisit the radar echo technique as an approach to detect ultra-high energy cosmic rays (UHECR). The UHECR extensive air showers generate disk-like ionization fronts propagating with a ...relativistic velocity and creating fast decaying plasma. We study the reflection of a radio wave, such as the one from a radar transmitter or commercial radio and TV station, from the relativistic ionization front. The reflected wave will be frequency upshifted due to the relativistic Doppler effect and propagate almost normally to the front due to relativistic aberration. The amplitude of the reflected wave depends strongly on the front velocity and parameters (density, collision frequency) of the plasma behind the front. We develop a theory that allows one to find the reflected wave. Using this theory and typical parameters of extensive air showers, we discuss the feasibility of UHECR detection.
Interrelation between the morphology, physiology, biochemistry, and productivity of potato plants was shown for the first time using the example of a mid-season-ripening variety (v.) Siversky and a ...mid-early Tretyakovka v. The yield of Siversky v. turned out to be 1.6 times higher than the yield of Tretyakovka. Aboveground biomass of Siversky v. was distinguished by an increased content of photosynthetic pigments, a greater variability of the protein and lipid metabolism indicators, and more intense oxidation processes and antioxidant protection, which can be the key to its greater productivity. Multivariate statistical analysis showed that the greatest relationship in the climatic conditions of central Russia in 2020 was found for productivity and such indicators as the stomata number per unit leaf area, the number of stems, and the content of pigments, phospholipids, neutral lipids, and water-soluble part of the protein. Thus, both morphological and physiological–biochemical properties can influence the course and direction of the production process, and, hence, the yield of a certain variety.
The purpose of the research is to identify and recommend for production or practical breeding varieties and hybrid potato material of various genetic and geographical origin, combining high yield, ...field resistance to mosaic viruses and adaptability to stressful abiotic environmental factors, optimize and improve the efficiency of field evaluation of potato varieties. The research was carried out in 2019-2021 in the Bezenchuk district of the Samara region. 2019 was characterized by a spring drought, and in 2020 and 2021 there was a spring-summer drought. The hydrothermal coefficient was 0.45; 0.47 and 0.61, respectively. In conditions of high temperatures and insufficient moisture, 36 new and promising potato varieties of domestic selection were evaluated according to a complex of economically valuable characteristics. The standards were the varieties Arosa, Gala, Zhigulevsky and Udacha. The experimental material was planted in four repetitions. The number of plants in repetition is 50. The predecessor is spring wheat. The soil of the experimental site is terraced chernozem, ordinary, low-humus, medium-thick, heavy loamy. High yields were characterized by medium-early varieties Krasa Meschery, Debut and Sudarinya, which exceeded the Gala standard by 9.9 t/ha, 4.8 t/ha and 2.8 t/ha; medium-ripened Siversky and Alaska (8.6 and 5.0 t/ha higher than the Zhigulevsky standard, respectively), as well as early-maturing Terra variety (5.0 t/ha above the standard Udacha) The same varieties have high indicators of field virus resistance at the level of 7...9 points to the most harmful X and Y viruses in the conditions of the Middle Volga region. Three main components that have the most significant impact on the variability of the studied parameters are identified. It is shown that field virus resistance was the main limiting factor of yield for the studied set of varieties under conditions of elevated air temperatures and insufficient humidification. The share of the first component accounted for 34.6 % of the variation of signs. It includes, with maximum loads of -0.801, -0.640 and -0.604, respectively, the yield and resistance to potato viruses X, S, and M. The productivity of the studied set of potato varieties was to the greatest extent due to field resistance to viruses X, S, M and, to a lesser extent, to virus Y.
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