A Warmer Arctic Compromises Winter Survival of Habitat-Forming Seaweeds

Continuous winter darkness at a latitude of 79°N was simulated in cultures of four species of Arctic seaweeds at 3 and 8°C. The laminarians Saccharina latissima and Alaria esculenta, and the rhodophytes Phycodrys rubens and Ptilota gunneri were monitored for 4 months in total darkness and after 1 week following light return in early spring, under controlled laboratory conditions. Biomass loss during darkness was enhanced by the high temperature in all species. At 8°C, the two laminarians were unable to resume growth upon re-illumination. Alaria esculenta showed new blade production by the end of the dark period, but only at 3°C. In all species, the photosynthetic ability was sustained, not suspended, during the whole dark period. P. rubens exhibited lower photosynthetic potential at 8°C than at 3°C during the darkness period, but it was able to recover its O2 evolving potential upon re-illumination, as P. gunneri and S. latissima did, but the latter only at 3°C. The reactivation of photosynthesis seemed to involve photosystem II over photosystem I, as 7 d of photoperiod after the prolonged darkness was not enough to fully recover the PAM-related photosynthetic parameters. Only small changes were recorded in the internal chemical composition (total C, total N, carbohydrates, proteins, and lipids), but species-specific differences were observed. Unlike subarctic areas with an operating photoperiod along the year, a warmer polar night might pose a limit to the ability of multi-year seaweeds to occupy the new ice-free illuminated areas of the Arctic coasts, so that newcomers will potentially be restricted to the spring-summer season.

Varietal features of photosynthetic activity of Tyumen seed oats when applying mineral fertilizers

The purpose is to study the varietal characteristics of the photosynthetic efficiency of oats when applying fertilizers in Western Siberia. Methods. The research was carried out on an experimental field located in the northern forest-steppe of the Trans-Urals. Photosynthetic potential and net productivity of photosynthesis were determined by the Nichiporovich’s method. Results. The nature of the formation of the assimilation surface and the accumulation of biomass of oat varieties Otrada, Talisman and Foma at different levels of mineral nutrition was studied. The photosynthetic potential and the net productivity of photosynthesis are calculated. The share of the influence of weather conditions, agrophone and variety on the studied indicators is determined. The Foma variety was characterized by maximum leafiness, compared to the Talisman and Otrada. On a natural agrophone, its assimilation surface in the sweeping phase reached 36.0 ± 5.5 thousand m2, at Otrada and Talisman – 28.1 and 24.0 thousand m2 per 1 ha of sowing. A very strong variability of the leaf surface area in Otrada was revealed (Cv = 24 %). The use of mineral fertilizers enhances the development of the leaf apparatus by 44–50 % and causes competition between oat plants. A close positive correlation was revealed between the leaf area in the sweeping phase and yield (r = 0.72). The area of the assimilation surface of oats is affected by: weather conditions – 37 %; nutrition level – 30 % and variety – 25 %. It was found that the Otrada and Foma varieties have the same accumulation dynamics and form the maximum photosynthetic biomass by the sweeping phase. The nature of biomass accumulation depends on weather conditions by 39 %; on mineral fertilizers by 29 % and on the genotype of the variety by 17 %. The productivity of the studied varieties is formed by increasing the assimilation surface, rather than increasing the efficiency of photosynthesis. Scientific novelty. For the first time, the photosynthetic potential was determined and the efficiency of the net photosynthesis productivity of oat varieties of the Tyumen selection was revealed. The share of the influence of various factors in the formation of the oat crop in the conditions of the Northern Trans-Urals has been established.

Influence of Probable Precipitation Futures on Strawberries (Fragaria x ananassa): Results from a Simulated Rainfall Experiment

It is well established that the interacting effects of temperature and precipitation will alter agroecological systems on a global scale. These shifts will influence the fitness of specialty crops, specifically strawberries (Fragaria x ananassa), an important crop in the Northeastern United States. In this study, four precipitation scenarios were developed that are representative of current and probable-future growing season precipitation patterns. Using a precipitation simulator, we tested these scenarios on potted day neutral strawberries. This study generated four primary results: (1) though treatments received different amounts of precipitation, little difference was observed in soil volumetric water content or temperature. However, treatments designed to simulate future conditions were more likely those designed to simulate current conditions to have higher nitrate-in-leachate (N-leachate) concentrations; (2) neither total precipitation nor seasonable distribution were associated with foliar or root disease pressure; (3) while there was a slightly higher chance that photosynthetic potential and capacity would be higher in drier conditions, little difference was observed in the effects on chlorophyll concentration, and no water stress was detected in any treatment; and (4) leaf biomass was likely more affected by total rather than seasonal distribution of precipitation, but interaction between changing rainfall distribution and seasonal totals is likely to be an important driver of root biomass development in the future.

Formation of photosynthetic parameters of winter wheat crops under foliar fertilization and herbicide application

Purpose. To study agronomic measures for the care of winter wheat: the use of foliar fertilization and protection against weeds with sulfonylureas. Methods. Field and laboratory. Results. It was investigated that the application of Bioforge anti-stress fertilizer did not significantly affect the growth of photosynthetic potential of crops, as the leaf surface area was not significantly different. In addition to the area of the photosynthetic leaf surface, there is a more accurate indicator, that is net productivity of photosynthesis, which can, in our opinion, more accurately show whether the effects of plant protection products against weeds lead to changes in physiological processes in the plant. the mechanism of action of the anti-stress agent is somewhat different. After all, the organization of the photosynthetic apparatus of plants can be such that for a relatively small area of leaves you can get better rates of dry matter accumulation. The best indicators of photosynthetic potential for the use of plant protection products in autumn were identified with the use of such products as Granstar Pro 75, WG, Logran 75, WG, Harmony 75, WG, for introduction into the phenophase BBCH 10–13, and in spring for use in BBCH 27–29 in combination with Bioforge and separately. However, the introduction of PIC 75, WG, to form the best photosynthetic potential of winter wheat crops should be carried out in the phase of BBCH 7–9 in autumn or spring in BBCH 25–26. We also investigated that the use of Bioforge anti-stress fertilizer did not significantly affect the growth of photosynthetic potential of crops. Conclusions. It was determined that the use of the anti-stress agent Bioforge had a positive effect on the condition of plants and their accumulation of dry matter. Accordingly, the best indicators of net productivity of wheat photosynthesis were obtained with the use in autumn of such products as Granstar Pro 75, WG, Logran 75, WG, Harmony 75, WG, for introduction into the phenophase BBCH 10–13, and spring for use in BBCH 27–29 in combination with Bioforge. However, the introduction of PIC 75, WG, to form the best photosynthetic potential of winter wheat crops should be carried out in the phase of BBCH 7–9 in autumn or spring in BBCH 25–26 in combination with Bioforge.

Morphological and anatomical features of winter rye leaves development

Differences of rye varieties in the length of lamina and sheath 1 - 6 from spike of the lamina and leaf sheath, width and area of the lamina were shown. The highest values of the studied leaf parameters were peculiar to the alien varieties of winter rye. It was found that foreign varieties were characterized by a smaller proportion of the plate area of the three upper leaves and a larger proportion for the 4th and 5th leaves (in % of the total leaf plate area). A characteristic feature of the laminae of the upper two leaves of winter rye is the absence of trichomes, instead of them there are spines 12 µm long, which are located above the conductive bundles on the adaxial side of the lamina. Stomata were located on both sides of the leaf, but there were more of them on the adaxial side of the lamina, where they were arranged in one or two rows on the flanks of the conductive bundles. Strong sclerification of conductive bundles was noted. In the most developed conducting bundles, sclerenchyma fibers were observed on both sides of the leaf lamina. The presence of stomata at the leaf sheath on both adaxial and abaxial sides is revealed. It was shown that the contribution of each leaf of upper and middle phytomeres to the total leaf area of winter rye varieties under study is different, which is important to consider when assessing their importance in the photosynthetic potential of plants.

The models of soybean varieties adapted to dry conditions

The article presents the analysis of early-ripening and mid-ripening promising and cultivated soybean varieties that received a comprehensive evaluation under irrigation conditions over the past period (2016-2018) of breeding with the increase in atmospheric drought and dry hot wind days to 77 with a long-term average annual indicator of 47 days with a relative humidity of less than 30%. We developed the scientifically based model of highly productive soybean varieties (2021-2023) with a yield of 2.8-3.8 t/ha and the growth season of 105-122 days. The model is based on the established correlations of the main morphological and biological characteristics with the grain productivity of irrigated sowing. The model of soybean varieties reflects characteristics that ensure the responsiveness of plants to watering and resistance to prolonged manifestations of atmospheric drought: a long growth season, low linear plant growth, significant leaf surface area, photosynthetic potential, dry biomass yield, number of plants before harvesting, thousand-seed weight, long-term duration of the “flowering-beans filling” period. The model is complemented by the indicators of high protein and fat content in seeds, as well as their yield from a unit of harvesting area.

Obtaining seeds of meadow clover in the Lower Volga region under irrigation

The purpose of the experiment was to develop a technology for cultivating meadow clover under irrigation to obtain the planned seed yields in the conditions of the Lower Volga region. Research methods. Field experiments, records and observations were carried out in accordance with the generally accepted methods of experimental work. As a result of the research, it was found that the total water consumption of clover crops varied over the years of the herbage life and depended on the given pre-irrigation threshold of soil moisture. It was highest in the variants with the maintenance of the 70 % pre-flood threshold: 3.6–3.9, the lowest 2.7–3.1 thousand m3/ha in the variants with the 60 % humidity threshold. With the differentiation of humidity by the development phases, the total water consumption varied from 3.1 to 3.5 thousand m3/ha. The share of irrigation water in the structure of total water consumption was 60.6–72.7 % according to the experimental variants. The leaf area depended on the water and nutrient regimes of the soil: it reached the maximum values in the variants with a 70 % pre-irrigation threshold of humidity and fertilization. In comparison with the increase in biomass, the seed productivity of clover was less dependent on the photosynthetic potential and assimilation surface. The highest seed yields were formed in the variants with improved nutrition background and maintenance of a differentiated irrigation regime – 280–730 kg / ha. The accumulation of a significant amount of root mass by clover had a positive effect on improving the ecological state of the irrigated area: the water-physical properties of the soil improved, and nutrients accumulated in it. Scientific novelty. In the conditions of the Lower Volga region, the dependence of the seed productivity of clover on the availability of water and nutrients, on the age of the herbage, was revealed. Their optimal combination is determined for the production of seed yields at the level of 400–700 kg/ha.

Effectiveness of herbicide application on potatoes in the northern forest-steppe of the Novosibirsk Ob region

The work aims to study the effectiveness of herbicides application on potato varieties of different ripeness groups in the conditions northern forest-steppe of the Novosibirsk Ob region. The authors obtained experimental data on leached chernozem in Novosibirsk district, Novosibirsk region, in 2017-2019. In their studies, the authors used common elements of potato cultivation tech- nology. The general background for potatoes in autumn fertiliser was applied at a dose of P60K90. Nitrogen fertilisers were used at a rate of 60 kg/ha in spring under pre-sowing cultivation. Herbicides Gezagard, Lazurit, Zenkor, Boxer, and mixtures of individual herbicides were applied before and after sprouting when potato plants were up to 12-14 cm high. Herbicides significantly reduced the infestation of potato varieties Lubava (early) and Tuleevsky (medium-season). The authors showed that the use of herbicides accelerated the processes of growth and development of potato varieties of two groups of ripeness. There was a significant increase in leaf area, photosynthetic potential, and 23-28% plant productivity. On a background of herbicides increase of yield by 30-35% is observed. There was an increase in the marketability of tubers by 10%. Used herbicides provided good quality and preservation of potato production. The authors note that the double application of herbicides Zenkor and Lazurit offers high rates of weed reduction. Thus yield and quality of presentation have high indicators. In tubers of potatoes, the residual quantity of herbicides is not detected. Application of herbicides economically and energetically practical. The level of profitability exceeds control 1,4 times on a background of double spraying by herbicides Zenkor and Lazurit.

Abscisic Acid in Coordination with Nitrogen Alleviates Salinity-Inhibited Photosynthetic Potential in Mustard by Improving Proline Accumulation and Antioxidant Activity

This investigation was done to assess the role of abscisic acid (ABA; 25 µM) and/or nitrogen (N; 10 mM) in the alleviation of salinity (NaCl; 100 mM)-induced reduction in photosynthetic activity and growth, N and sulfur (S) assimilation of mustard (Brassica juncea L.) cv. RH0-749. Salinity treatment caused oxidative stress and significantly elevated the content of both H2O2 and thiobarbituric acid reactive substances (TBARS), and impaired photosynthetic activity and growth, but increased the content of nitrogenous osmolyte proline and the activity of antioxidant enzymes involved in the metabolism of reactive oxygen species. The application of 25 µM ABA under a controlled condition negatively affected photosynthesis and growth. However, ABA, when combined with N, minimized oxidative stress and mitigated the salinity-inhibited effects by increasing the activity of antioxidant enzymes (superoxide dismutase, SOD; glutathione reductase, GR; ascorbate peroxidase, APX) and proline content. Overall, the supplementation of 10 mM N combined with 25 µM ABA provides an important strategy for enhancing the photosynthetic potential of B. juncea under saline conditions.

Photosynthetic activity and productivity of durum wheat (Triticum durum Desf.) affected by certain preparations and various terms of sowing

In 2019-2020, in the experimental field of the Field Crops Institute, Chirpan a field experiment with durum wheat cultivar Predel (Triticum durum Desf.) was conducted. Three sowing dates were tested: Early sowing (05 – 10 October), Normal sowing (20-25 October – standard) and Late sowing (05-10 November). In early sowing, 2 retardants were studied: Cearon 480 SL – 1 l/ha and Medax top – 1 l/ha and 2 insecticides: Proteus 110 OD – 625 ml/ha and Mageos – 100 g/ha, as well as the mixtures between them. During late sowing, 2 stimulants were studied: Naturamin plus – 1.5 l/ha and Raiza mix – 750 ml/ha and 2 foliar liquid fertilizers: Mix for cereal SC – 1.5 l/ha and Trimax SC – 1.5 l/ha, as well as the mixtures between them. These preparations and fertilizers are applied after stage 3-4 leaves of durum wheat, in the so-called “Closure of crops”. In the case of early sowing variants, this stage occurs in autumn, and in the case of late sowing variants, the stage occurs in spring. In the early sowing of durum wheat, the leaf area, photosynthetic potential, biological and economic yield are the greatest in the combinations of retardants Cearon and Medax top with the insecticides Proteus and Mageos. In the late sowing of durum wheat, the leaf area, photosynthetic potential, biological and economic yield are the highest in the combinations of the stimulants Naturamin plus and Raiza mix with the leaf fertilizers Mix for cereals and Trimax. In these variants, the leaf area dies faster during the milk development stage. The net photosynthesis productivity in the combinations is lower than in the independent use of the respective preparations and fertilizers. The harvest index in the late and normal sowing variants is higher than in the early durum wheat sowing variants.